Proceedings of the 2012 BFRS Workshop

Blodgett Forest Research Station Workshop – 2012 1

Whitaker’s Forest Research Station


Proceedings

Of the

Blodgett Forest Research Station

2012 Research Workshop

January 27 – 28, 2012

The Center for Forestry provides leadership in the development of basic scientific

understanding of ecosystem processes, human interactions and value systems, and

management and silvicultural practices that ensure the sustainability of forest land.

The Center pulls together interdisciplinary teams of campus faculty, Cooperative

Extension specialists and advisors, and staff from various agencies and organizations

to develop research projects, outreach and public education activities, and provides

policy analysis on issues affecting California’s forest lands.

Ongoing research at research forest aims to provide knowledge to improve

management of forests in such a manner that basic air, water, soil, and biological

resources are conserved.

The Center for Forestry currently manages 4 research forest properties in California:

UC Forestry Camp/Baker Forest (Plumas County)

Blodgett Forest Research Station (El Dorado County)

Russell Research Station (Contra Costa County)

Whitaker’s Forest Research Station (Tulare County)

More information about the Center for Forestry and the College of Natural Resources

research forests can be found at www.forestry.berkeley.edu.

http://www.forestry.berkeley.edu/


Attendees

Sasha Clark* University of California, Berkeley

Brandon Collins* USDA Forest Service

Sabina Dore* University of California, Berkeley

Mellisa Eitzel * University of California, Berkeley

Helge Enge CALFIRE

Cathy Fahey * University of Florida

Rob Fecko Sierra Pacific Industries

Danny Fry* University of California, Berkeley

Brett Furnas* California Dept. Fish & Game

Teri Griffis * CALFIRE

Mila Hickenbottom University of California, Davis

Chris Hipkin SFS

Stacy Hishinuma USDA Forest Service/UC Davis

Erik Jensen Independent forester

Dryw Jones* University of California, Berkeley

Peter Kerr *° California Dept. Fish & Game

Susan Kocher UC Cooperative Extension

Kevin Krasnow* University of California, Berkeley

Andrew Latimer University of California, Davis

Jeff Leddy CALFIRE

Amy Mason University of California, Berkeley

Katie McGown University of California, Berkeley

Dan Obrist * Desert Research Institute

Kevin O'Hara* University of California, Berkeley

Jessica Pierce Placer Land Trust

Ricky Satomi° University of California, Berkeley

Russell Seufert University of California, Berkeley

Steve Seybold * USDA Forest Service/UC Davis

Frieder Schurr University of California, Berkeley

Ken Somers° University of California, Berkeley

Rick Standiford University of California, Berkeley

Scott Stephens University of California, Berkeley

Jens Stevens * University of California, Davis

Bill Stewart* University of California, Berkeley

Kenton Stutz University of California, Berkeley

Ariel Thomson* University of California, Berkeley

Kip Will University of California, Berkeley

Tong Wu* University of California, Berkeley

Jennifer York University of California, Berkeley

Rob York* University of California, Berkeley

Derek Young University of California, Davis

*presentation °poster


Table of Contents The effects of fire and mechanical fuel treatments on avian abundance in Sierra

Nevada mixed-conifer forest 8 Andrew J. Amacher, Reginald H. Barrett, and Scott L. Stephens

Within-crown and whole-tree water use patterns in ancient giant sequoia

(Sequoiadendron giganteum) trees 10 Anthony Ambrose, Stephen Sillett, Todd Dawson, George Koch, Stephen Burgess, Marie Antoine,

Cameron Williams, Jim Spickler, Rikke Næsborg, Wendy Baxter, Russell Kramer, & Robert Van Pelt

Contributions of biogenic volatile organic compounds to net ecosystem carbon flux in

a ponderosa pine plantation 12 Nicole C. Bouvier-Brown, Gunnar W. Schade, Laurent Misson, Anita Lee, Megan McKay, Allen H.

Goldstein

Toward a better understanding of the "Transverse Range break": lineage

diversification in southern California 13 Stylianos Chatzimanolis and Michael S. Caterino

Estimating the atmospheric boundary layer height over sloped, forested terrain from

surface spectral analysis during BEARPEX 14 W. Choi, I. C. Faloona, M. McKay, A. H. Goldstein, and B. Baker

Mixed conifer tree ring phenology 15 Sasha Clark, Scott Stephens, Danny Fry, Brandon Collins, and Jen York

Extended impacts of fuel treatments on forest structure, fuel loads, and potential fire

behavior in Sierra Nevada mixed-conifer forests 16 Brandon M. Collins, Scott L. Stephens, Gary Roller

Effects of fire and forest management on soil respiration at Blodgett 19 Sabina Dore, Danny Fry, and Scott Stephens

Something about statistics: Tree growth from forest inventories 21 Melissa Eitzel, John Battles, Rob York, Jonas Knape, Perry de Valpine

Arbuscular mycorrhizal colonization of giant sequoia (Sequoiadendron giganteum) in

response to restoration practices 23 Catherine Fahey and Robert A. York

Aminocyclopyrochlor sequoia tolerance trials 25 Ed Fredrickson

Examination of tree-ring development in the five mixed conifer forest species 26 Danny Fry, Jen York, Scott Stephens, and Brandon Collins

Lidar scanning for feature extraction 28 Kyle Holland and Gregory Biging


Genetic characterization of slenders salamanders (Batrachoseps) from the Whitaker

Forest 29 Elizabeth Jockusch

Biomass in sequoia vs. Sierra mixed-conifer stands 30 Anne E. Kelly, Paige Austin, Glenn Cajar, Michael L. Goulden

Fungus gnats of California 31 Peter H. Kerr

The burning QuKe question 32 Kevin Krasnow and Scott Stephens

Closing the peroxy acetyl nitrate budget: observations of acyl peroxy nitrates (PAN,

PPN, and MPAN) during BEARPEX 2007 35 B.W. LaFranchi, G. M.Wolfe, J. A. Thornton, S. A. Harrold, E. C. Browne, K. E. Min, P. J. Wooldridge,

J. B. Gilman, W. C. Kuster, P. D. Goldan, J. A. de Gouw, M. McKay, A. H. Goldstein, X. Ren, J. Mao,

and R. C. Cohen

Observations of the temperature dependent response of ozone to NOx reductions in

the Sacramento, CA urban plume 36 B.W. LaFranchi, A. H. Goldstein, and R. C. Cohen

Examining variability in Douglas-fir growth at a continental scale 37 Christina Lyons-Tinsley and David L. Peterson

Measuring up to managers' needs: quantifying the persistence of a fuel reduction

treatment in a giant sequoia-mixed conifer forest 38 Mary Mayeda and Robert York

Evidence for unusual peroxy nitrates and their atmosphere-biosphere exchange 40 Min, Kyung-Eun, Pusede, S. E., Browne, E. C., LaFranchi, B. W., Lee L., Wooldridge, P. J., Wolfe, G.

M., Harrold, S. A., Thornton J. A., Park, J.-H., Weber, R.J., Goldstein, A.H., and Cohen, R. C.

Flux-gradient relationships of nitrogen oxides over a ponderosa pine plantation

during BEARPEX-2009 41 Min, Kyung-Eun, Pusede, S. E., Browne, E. C., LaFranchi, B. W., Wooldridge, P. J., and Cohen, R. C.

Gaseous elemental mercury emissions and CO2 respiration rates in terrestrial soils

under controlled aerobic and anaerobic laboratory conditions 42 Daniel Obrist , Xavier Faïn, and Carsen Berger

Terrestrial mercury (Hg) surface reservoirs: magnitude, spatial patterns, fate, and

re-emission potential to the atmosphere 43 Daniel Obrist

Interactions between planting density and tree architecture on leaf area index

development in giant sequoia 45 Kevin L. O’Hara and Robert A. York


Estimating BVOC (Biogenic Volatile Organic Compound) emissions by flux-gradient

relationship during BEARPEX 2009 47 Jeong-Hoo Park, Silvano Fares, Robin Weber, and Allen H. Goldstein

Influence of bio-mass & fire reduction techniques on soil strength in a Sierra Nevada

mixed conifer forest 48 Jennifer Podvin, Amara Johnson, and Robert A. York

Fate of mercury in tree litter during decomposition 49 A. K. Pokharel and D. Obrist

Measurement of atmospheric nitrous acid at Blodgett Forest during BEARPEX 2007 50 X. Ren, H. Gao, X. Zhou, J. D. Crounse, P. O. Wennberg, E. C. Browne, B. W. LaFranchi, R. C. Cohen,

M. McKay, A. H. Goldstein, and J. Mao

A relaxed eddy accumulation system for measuring vertical fluxes of nitrous acid 52 X. Ren, J. E. Sanders, A. Rajendran, R. J. Weber, A. H. Goldstein, S. E. Pusede, E. C. Browne, K.-

E. Min, and R. C. Cohen

Aircraft measurements of the impacts of pollution aerosols on clouds and

precipitation over the Sierra Nevada 53 Daniel Rosenfeld, William L. Woodley, Duncan Axisa, Eyal Freud, James G. Hudson, and Amir Givati

Update on the status of the goldspotted oak borer in California 54 Steven J. Seybold and Tom W. Coleman

Giant sequoia seed production 57 K. Somers, R. York, T. Griffis, M. Holton, D. Katz and C. Crilley

Prescribed fire and mechanical thinning effects on subsequent bark beetle caused

tree mortality in a mid-elevation Sierran mixed-conifer forest 60 Daniel T. Stark, David L. Wood, Andrew J. Storer, Scott L. Stephens

Invasion dynamics of Scotch and Spanish broom at the range margin 61 Jens Stevens and Andrew Latimer

Aging of large giant sequoia 62 Ariel Thomson and Robert A. York

Stabilization of diverse microbial residues in California and Puerto Rico forest soils 64 Heather Throckmorton, Jeffrey Bird, Laura Dane, Mary Firestone, and William R. Horwath

Application of scanning calorimetry to estimate soil organic matter loss after fires 66 Sergey V. Ushakov, Divya Nag, Alexandra Navrotsky

Eddy fluxes of nuclei mode particles to pine forest during BEARPEX’09 69 Richard J. Vong, Ivar J. Vong, David S. Covert

Size-dependent aerosol deposition velocities during BEARPEX’07 74 Richard J. Vong, Ivar J. Vong, Dean Vickers, David S. Covert


Origins and composition of fine atmospheric carbonaceous aerosol in the Sierra

Nevada Mountains, California 75 David R. Worton, Allen H. Goldstein, Delphine K. Farmer, Kenneth S. Docherty, Jose L. Jimenez,

Jessica B. Gilman, William C. Kuster, Joost de Gouw, Brent J. Williams, Nathan M. Kreisberg, Susanne

V. Hering, Graham Bench, Megan McKay, Kasper Kristensen, Marianne Glasius, Jason D. Surratt, and

John H. Seinfeld

Seasonal differences in isoprene and monoterpene organosulfate concentrations

above a ponderosa pine forest in California 77 David R. Worton, Jason D. Surratt, John H. Seinfeld, Kasper Kristensen, Marianne Glasius, Jeong-Hoo

Park, Melinda Beaver, Paul Wennberg, and Allen H. Goldstein

The Center for Forestry website: Changes and future directions 79 Tong Wu

Growth response of large, old giant sequoia trees to a disturbance intensity gradient 80 Robert A. York and Scott Sink

A gap-based approach for regenerating pine species and reducing surface fuels in

multi-aged mixed conifer stands in the Sierra Nevada, California 81 Robert A. York, John J. Battles2, Rebecca C. Wenk, and David Saah

Density effects on development of young giant sequoia (sequoiadendron giganteum):

Growth trends and competition dynamics through 22 years 83 Robert A. York, Kevin L. O’Hara, and John J. Battles

Size structure of giant sequoia at Whitaker’s Forest in the context of all southern

Sierra groves 85 Robert A. York and John J. Battles

Stem breakage probability in mature mixed conifer plantations 87 Robert A. York and Rose DeVries


The effects of fire and mechanical fuel treatments on avian abundance in Sierra Nevada mixed-conifer forest

Andrew J. Amacher, Reginald H. Barrett, and Scott L. Stephens

Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA

We resampled avian point count plots at Blodgett Forest Research Station nine years after

treatments were completed for the Fire and Fire Surrogate (FFS) experiment. FFS researchers

randomly selected 12 mixed-conifer stands from a set of available stands. Each stand was

assigned to four treatment groups: controls (no treatment), prescribed fire only (surface fires in

fall 2002 and fall 2010), mechanical only (thinning from below followed by rotary mastication),

and mechanical plus fire (mechanical treatment followed by surface fire in fall 2002). We

conducted six point count plots within each replicate stand following standardized protocols. We

visited each plot three times in May and June of 2011. Data were counts, and analyzed using

Poisson regression procedures. As a preliminary analysis, we analyzed the data as a set of

competing models using QAICc model selection procedures. The following models were tested:

constant effects (null model), treatment effects (the four FFS treatments), fire effects (fire only

and mechanical plus fire combined vs. control and mechanical only combined), total live stand

basal area (m2/ha), total hardwood stand basal area (m

2/ha), and total snag stand basal area

(m2/ha). Models were evaluated using QAICc model weights (wi). For the purposes of this

analysis, models with wi > 0.70 are considered to have moderate support relative to the other

models (wi’s sum to 1.0 over all six models). Three of 18 bird species had one model with a wi >

0.70. The fire effects model had wi > 0.70 for three species: Brown Creeper (Certhia Americana),

Mountain Chickadee (Poecile gambeli), and Western Wood Pewee (Contopus sordidulus). All

three species had greater abundance in stands treated with fire. The Brown Creeper nests under

loose bark (typically on snags) whereas the Mountain Chickadee is a secondary cavity nester, and

is dependent on cavities created by other species. Fires may have benefited both species via the

creation of more nesting substrates (snag creation). The Western Wood Pewee is an aerial forager

(flycatcher), and fire treatments may have opened more aerial foraging space within the midstory

and understory for this species. In 2003 and 2004, pewee nests increased post-treatment in

mechanical only and mechanical plus fire treatments, but only slightly in fire only units. The

2010 fires created some “hot spots” within the canopy, and pewees were observed foraging within

these areas. Repeated fires may open sufficient space for pewees to nest and forage within the fire


only units through the creation of spatial patchiness within the stands. This analysis is

preliminary, and a more detailed analyses incorporating previous years of data will shed light on

species responses to treatments through time.


Within-crown and whole-tree water use patterns in ancient giant sequoia (Sequoiadendron giganteum) trees

Anthony Ambrose1, Stephen Sillett2, Todd Dawson1, George Koch3, Stephen Burgess4, Marie Antoine2, Cameron Williams1, Jim Spickler2, Rikke Næsborg1,

Wendy Baxter1, Russell Kramer2, & Robert Van Pelt2

1 Department of Integrative Biology, University of California, Berkeley, CA 2 Department of Forestry and Wildland Resources, Humboldt State University, Arcata, CA 3 Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 4 School of Plant Biology, University of Western Australia, Perth, WA, Australia

Giant sequoia (Sequoiadendron giganteum) are the largest and among the oldest living

organisms on Earth, reaching 1,489 m3 wood volume, 94.5 m height, and 3,200 years of age.

Large and old Sequoiadendron trees often have massive complex crowns that experience highly

variable environmental conditions at any given moment in time. Vertical and horizontal

heterogeneity in climatic factors such as light, temperature, and humidity interact with changes in

xylem water potential and tree structure throughout individual crowns to determine water and

carbon exchange rates at leaf, branch, and whole-tree scales. However, our understanding of how

variation in these factors influences water-use and subsequent carbon gain in such large trees is

limited. To increase this understanding we conducted a preliminary study with the following two

primary objectives: (1) to characterize within-crown and whole-tree water-use patterns in ancient

Sequoiadendron trees, and (2) to examine the structural and environmental factors driving these

patterns. We measured sapflow rates throughout the crowns of 3 Sequoiadendron trees growing at

the Whitaker Forest Research Station (WFRS) in July 2009 and August 2010. Study tree basal

diameters ranged from 5.2 to 5.9 m and heights from 85.9 to 90.1 m. The crown structure of each

tree was mapped using rope-based arborist techniques. Sapflow was measured in 8 branches in

lower, middle, and treetop crown locations in each tree in 2009 (24 branches total), and in 6

branches in lower, middle, and treetop crown locations in 2 trees in 2010 (12 branches total).

Sample branches ranged from 3.9 – 10.5 cm basal diameter. Sapflow was also measured at the

tree base, live crown base, and treetop in the main trunk of 2 trees in 2010. Temperature and

humidity were measured and hemispherical photographs were obtained to characterize light

conditions of each branch. Diurnal xylem water potential patterns were also measured on all

sample branches in 2009 and on a subsample of branches in 2010. We observed significant

differences in diurnal patterns of branch xylem water potential that reflected height gradients (i.e.,

decreasing water potential with increasing height) and solar radiation exposure (i.e., branches on


the eastern side of the crown experienced lower water potential in the morning while branches on

the western side of the crown experienced lower water potential in the afternoon). In contrast, no

significant differences were observed in atmospheric vapor pressure deficit among branches.

Diurnal patterns of branch transpiration and average stomatal conductance were significantly

correlated with direct solar radiation levels with time lags ranging from 0-4 hours, but were not

significantly correlated with vapor pressure deficits. We observed large variation in main trunk

sapflow rates among different radii that closely followed the daily trajectory of solar exposure

(i.e., increased flows on the eastern side of the trunk in the morning and increased flows on the

western side of the trunk in the afternoon). Radial profiles of trunk sap velocity showed the

highest flow rates several centimeters inside the cambium. These preliminary results highlight the

complex nature of water-use in large Sequoiadendron. Ongoing analyses will estimate whole-tree

sapflow rates and further explore the relationship between within-crown and whole-tree water use

patterns.


Contributions of biogenic volatile organic compounds to net ecosystem carbon flux in a ponderosa pine plantation

Nicole C. Bouvier-Brown a,b, Gunnar W. Schade a,c, Laurent Misson a,d, Anita Lee a,e, Megan McKay a,f, Allen H. Goldstein a

a Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA b Permanent Address: Chemistry and Biochemistry Department, Loyola Marymount University, Los Angeles, CA c Permanent Address: Department of Atmospheric Sciences, Texas A&M University, College Station, TX d Deceased e Permanent Address: US Environmental Protection Agency, Region 9 f Permanent Address: California Air Resources Board, Sacramento, CA

When assessing net ecosystem exchange (NEE) and net ecosystem carbon balance

(NECB), respiration is generally assumed to be the only significant loss of carbon to the

atmosphere. However, carbon is also emitted from ecosystems in the form of biogenic volatile

organic compounds (BVOCs). Here we consider the magnitude of systematic difference caused

by omitting this additional carbon loss from the net ecosystem carbon balance, as compared to the

NEE term, of the ponderosa pine plantation at Blodgett Forest. We find that 9.4 (range 6.2 – 12.5)

g C m-2

yr-1

were emitted from this ecosystem as BVOCs. This is 4.0 (2.0 – 7.9) % of annual

NEE, and neglecting this additional loss of carbon causes an overestimation of carbon storage for

this rapidly growing commercial forest plantation. For ecosystems that are not storing carbon as

rapidly, where photosynthesis and respiration are more closely balanced, ignoring BVOC

emission may cause a larger error in the estimation of NECB.


Toward a better understanding of the "Transverse Range break": lineage diversification in southern California

Stylianos Chatzimanolis and Michael S. Caterino

Department of Invertebrate Zoology, Santa Barbara Museum of Natural History, Santa Barbara, CA

The Transverse Ranges in southern California have been identified as having a prominent

phylogeographic role. Numerous studies have identified distinct north-south and/or east-west

lineage breaks involving the Transverse Ranges. However, in evaluating their findings, most

authors have regarded this complex system somewhat simplistically. In this study we more deeply

investigate these breaks using two approaches: first we examine the phylogeographic history of

Sepedophilus castaneus (Coleoptera: Staphylinidae) and then implement a comparative

phylogeography approach applying Brooks parsimony analysis to the topologies of nine

additional taxa. Phylogenetic analysis, nested clade analysis, and AMOVAs for S. castaneus agree

that there is a major lineage break between the eastern and western Transverse Ranges, localized

between the Sierra Pelona and the San Gabriel Mountains. The comparative phylogeographic

analysis supports a generally strong concordance of area relationships with geographic proximity.

It is notable, however, that the Transverse Ranges as a group do not show phylogenetic cohesion,

but rather they are split into three main regions: an eastern region (San Gabriel, San Bernardino,

and San Jacinto Mountains), a central region (central Transverse Ranges and Sierra Pelona) that is

often grouped with the Tehachapi and Sierra Nevada populations, and a western region

(northwestern Transverse Ranges and Santa Ynez Mountains) that is consistently grouped with

coast range areas to the north. The lineage break between east and west Transverse Ranges is

attributable to the presence of a marine embayment in what is now the Santa Clara River valley 5-

2.5 million years ago.


Estimating the atmospheric boundary layer height over sloped, forested terrain from surface spectral analysis during BEARPEX

W. Choi1,*, I. C. Faloona1, M. McKay2,**, A. H. Goldstein2, and B. Baker3

1 Department of Land, Air, and Water Resources, UC Davis, CA

2 Department of Environmental Science, Policy, & Management, University of California, Berkeley, CA

3 Department of Chemistry, CSU Sacramento, CA

*now at: Department of Atmospheric & Oceanic Sciences, UC Los Angeles, CA

**now at: California Air Resources Board, Sacramento, CA

The atmospheric boundary layer (ABL) height (zi) over complex, forested terrain is

estimated based on the power spectra and the integral length scale of cross-stream winds obtained

from a three-axis sonic anemometer during the two summers of the BEARPEX (Biosphere Effects

on Aerosol and Photochemistry) Experiment. The zi values estimated with this technique show

very good agreement with observations obtained from balloon tether sondes (2007) and

rawinsondes (2009) under unstable conditions (z/L < 0) at the coniferous forest in the California

Sierra Nevada. On the other hand, the low frequency behavior of the streamwise upslope winds

did not exhibit significant variations and was therefore not useful in predicting boundary layer

height. The behavior of the nocturnal boundary layer height (h) with respect to the power spectra

of the v-wind component and temperature under stable conditions (z/L > 0) is also presented. The

nocturnal boundary layer height is found to be fairly well predicted by a recent interpolation

formula proposed by Zilitinkevich et al. (2007), although it was observed to only vary from 60-80

m during the 2009 experiment in which it was measured. Finally, significant directional wind

shear was observed during both day and night soundings. The winds were found to be consistently

backing from the prevailing west-southwesterlies within the ABL (the anabatic cross-valley

circulation) to southerlies in a layer ~1-2 km thick just above the ABL before veering to the

prevailing westerlies further aloft. This shear pattern is shown to be consistent with the forcing of

a thermal wind driven by the regional temperature gradient directed east-southeast in the lower

troposphere.


Mixed conifer tree ring phenology

Sasha Clark1, Scott Stephens1, Danny Fry1, Brandon Collins2, and Jen York1

1Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA

2Fires and Fuels Program, Pacific Southwest Research Station, USDA, Forest Service, Redding, CA

The position of fire scars within annual rings of conifer trees has been widely used in fire

history studies to determine past fire seasonality. However, there has not been a systematic study

of annual ring development and factors influencing the variation. This study seeks to develop an

understanding of tree ring phenology in the mixed conifer forest species of the Sierras: ponderosa

pine, sugar pine, Douglas fir, white fir, and incense cedar. Specifically, we seek to identify the

timing of the onset and cessation of earlywood and latewood growth, and the affects of factors

such as climate, crown position, species, tree size, and site. Three replicates of each of the five

species in six compartments, all chosen for high vigor, have been cored every two weeks during

the growing season for three consecutive years (2009-2011). These cores are then processed and

earlywood and latewood width measurements since 2005 are taken in micrometers using a

Velmex sliding stage. This data will allow us to better understand tree ring phenology and its

influencing factors, possibly leading to more accurate assessments of past fire seasonality.

Figure from Clark, Stephens, Fry, Collins, and York: Mixed conifer tree ring phenology.


Extended impacts of fuel treatments on forest structure, fuel loads, and potential fire behavior in Sierra Nevada mixed-conifer forests

Brandon M. Collins1, Scott L. Stephens

2, Gary Roller

1

1Fires and Fuels Program, Pacific Southwest Research Station, USDA, Forest Service, Redding, CA

2Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA

We re-measured stands treated as part of the national Fire and Fire Surrogate study to

investigate longer-term change associated various fuel treatment types: prescription burning alone

(burn only), thinning from below followed by mastication of sub-merchantable material (thin

only), and the same thinning followed by prescription burning (thin&burn), as well as an

untreated control. Plots within these stands were measured in 2001 to capture pre-treatment (PRE)

forest structure and fuel loads, then again in 2003 to capture one-year post-treatment (POST-1YR),

and most recently in 2009 to capture seven years post-treatment (POST-7YR). Based on these plot

measurements we calculated the following stand structure metrics and fuel loads for each time

period: live tree density, canopy cover, and basal area, as well as duff, litter, fine woody, and

coarse woody fuel loads. Additionally, we modeled potential fire behavior for each plot, at each

time step, with the Fire and Fuels Extension to the Forest Vegetation Simulator. Using these

calculated metrics, fuel loads, and fire behavior predictions we tested for differences among time

periods (PRE, POST-1YR, and POST-7YR) and among treatments (control, burn only, thin only, and

thin&burn) with a repeated measures analysis. Differences among time periods and treatments

were inferred from Tukey-Kramer adjusted p-values, with α = 0.05.

Tree density (live trees > 15.2 cm dbh) was similar in the control across time periods (PRE,

POST 1YR, POST 7YR), while both live basal area and canopy cover increased significantly POST-

7YR relative to the PRE and POST-1YR. Both thinning treatments significantly reduced tree density

and basal area POST-1YR, relative to PRE levels and POST-1YR control. By POST-7YR tree densities

were unchanged in both thinning treatments, relative to POST 1-YR, while basal area and canopy

cover increased significantly in the thin only, relative to POST 1-YR. Despite this increase, basal

area in the thin only POST-7YR was significantly lower than that in both the thin only PRE and the

control POST-7YR. Canopy cover and basal area in the thin&burn treatment was unchanged POST-

7YR relative to POST-1YR, and was significantly below that for the control POST-7YR.Tree density

did not change initially in the burn only treatment, but did decline significantly by POST-7YR,

relative to POST-1YR and PRE levels, as well as all three time periods for the control. Basal area


and canopy cover in the burn only treatment did not change significantly over time.

Species composition was generally stable across time periods and treatments, with a few

exceptions. Both thinning treatments in POST-1YR and POST-7YR had a significantly lower

proportion of incense cedar, relative to PRE levels. Pine proportion in both thinning treatments

POST-7YR was significantly greater than PRE levels. In the thin&burn treatment pine proportion

POST-7YR was significantly higher than all other treatments POST-7YR, while both hardwood and

white fir proportion POST-7YR was significantly lower than PRE thin&burn only.

Duff, litter, fine woody, and coarse woody fuel loads were significantly reduced in both

burning treatments POST-1YR, relative to PRE levels, as well as POST-1YR for the control. These

reductions relative to PRE levels held POST-7YR in all fuel classes, but were not statistically

different from POST-7YR control for all fuel classes except duff. Litter loads increased POST-7YR in

both burning treatments relative to POST-1YR for the same treatments, and were not different from

the other treatments POST-7YR. Litter and duff loads in the thin only treatment were stable over

time and statistically indistinguishable from the control at all time periods. Fine woody fuel loads

in the thin only treatment increased significantly from PRE to POST-1YR, and then decreased

significantly from POST-1YR to POST-7YR. The only statistically significant difference in fine

woody fuel loads among treatments POST-7YR is between the thin only (higher) and the thin&burn

(lower) treatments. Coarse woody fuel loads in the thin-only treatment did not change PRE to

POST-1YR, but decreased significantly from POST-1YR to POST-7YR. There were no differences in

coarse woody fuel loads among treatments POST-7YR.

Canopy base height was stable in the control and burn only treatment from PRE to POST-

1YR, but decreased for the control and increased in the burn only from POST-1YR to POST-7YR.

Canopy bulk density was stable across all three time periods in the control, and from PRE to POST-

1YR for the burn only. By POST-7YR in the burn only canopy bulk density decreased significantly

relative to PRE and POST-1YR. Canopy base height increased significantly and canopy bulk density

decreased significantly from PRE to POST-1YR for both thinning treatments. These relationships

held POST-7YR, relative to PRE, with the exception of canopy base height for thin only, which

decreased significantly and was not statistically different from the PRE level. Predicted flame

length and torching probability was significantly lower in the two burning treatments POST-1YR

and POST-7YR relative to PRE levels and to the control at all time periods. In the thin only predicted

flame length and torching probability was unchanged from PRE to POST-1YR, but by POST-7YR


both decreased significantly, and were statistically indistinguishable from POST-7YR in the two

burning treatments. Predicted flame length was stable in the control across all time periods, but

torching probability increased significantly POST-7YR, relative to both PRE and POST-1YR.


Effects of fire and forest management on soil respiration at Blodgett

Sabina Dore, Danny Fry, and Scott Stephens


Respiration processes release part of the carbon assimilated trough photosynthesis and determine

the net balance of carbon stored in ecosystems. Soil CO2 efflux (soil respiration) has been estimated to

account for 60–90% of the total ecosystem respiration in temperature forests (Goulden et al., 1998;

Valentini et al., 2000; Law et al., 2001). Soil respiration is a complex process, where CO2 is produced by

microorganisms in the soil (heterotrophic component) and by roots (autotrophic component). The CO2

produced in the soil is then released to the atmosphere depending on diffusivity of CO2 through the soil

and the soil-atmosphere CO2 concentration gradient. Many factors, including temperature and soil

moisture, wind, and atmospheric pressure fluctuations can affect the efflux of CO2 from soil.

Disturbances impact soil respiration and affect greatly post-disturbance ecosystem carbon balance,

but these impacts are still poorly studied and understood. In literature the effect of disturbances on soil

respiration is dependent on the type of disturbance, its intensity, vegetation type, and climate. Studies have

found an increase, or decrease or no change in soil respiration in response to disturbance. This is because

disturbances affect the heterotrophic and autotrophic component of soil respiration separately. Usually the

heterotrophic component is increased by disturbance because of an increase of necromass, whereas the

autotrophic component is decreased because of a loss of living individuals and mass. It is their relative

changes that determine the post disturbance soil respiration rate.

We applied two different techniques to measure soil respiration. A closed dynamic chamber

method (Licor 6002 and 6000-9, Licor, Lincoln, NE), and a profile technique (based on GMT222 probes,

Vaisala, Helsinki, Finland). The chamber method calculates soil respiration from the increment of CO2

concentration in time in a volume of air enclosed above the soil surface. It is portable and allows

quantification of the high spatial variability of soil respiration. However measurements made every two

weeks do not quantify soil respiration variability in time. Our chamber enclosed a soil surface area of 72

cm2, had a pressure compensation valve, and controlled the CO2 concentration not to alter the natural soil-

atmosphere CO2 gradient. Additional measurements of soil temperature and soil water content were taken

with each soil respiration measurement. Collars were inserted in the soil to have permanent measurement

plots and to reduce disturbance when inserting the chamber in the soil. The profile method calculates soil

respiration from measurements of CO2 concentration at different soil depths and from determination of the

CO2 diffusivity in the soil. The probes were at depth of 2, 8, 16 and 24 cm. We also measured soil

temperature at the same depths, soil water content at 5 and 20 cm, air temperature, air relative humidity

and atmospheric pressure. Profile measurements were continuous, but because these systems require high


power, intense maintenance and are costly, one replicate per site was installed. The two techniques validate

and also complement each other.

We analyzed the effects of two different types of disturbance on soil respiration at Blodgett. Soil

respiration was measured in four different stands: 1) a stand subject to a prescribed fire, used to reduce fuel

load and restore lower tree density; 2) a control, undisturbed stand. Measurements were also made in a

stand subject to harvest. In this site we compared soil respiration from 3) an area subject to a soil

preparation practice, soil ripping and 4) an area were no soil preparation treatment was applied (no-rip).

The profile measurements have one replicate per site and measurements started in summer 2009

for the fire/control sites, summer 2010 for the rip/no-rip sites. Chambers measurements at the fire/control

sites have 27 plots covering different topographic and vegetation types. At the rip/no-rip sites, 6 x 2

replicates plots were located outside the harvested area as a control treatment, and 9 x 2 replicates in the

soil ripped and no-rip plots. Regular measurements started in June 2011.

We present preliminary results from our study. Because of technical problems in the profile

measurements and the short measurement period over which chamber measurements were made additional

data are needed to quantify the effects of disturbances on soil respiration at Blodgett. First results showed

that treatments changed the sites microclimate. Soil temperature was higher in the partially open canopy at

the fire site, and even more in the harvested site compared to the control site. Soil water content was higher

in the fire site than the control site. The treatments, however, didn’t change the relationship between soil

respiration and soil temperature. Soil temperature had the strongest control on soil respiration at the

harvested site, then at the fire site, and last at the control site. The deepest soil temperature (24 cm) had a

stronger control on soil respiration than the air and the more superficial soil temperatures. Chamber

measurements showed higher soil respiration in the control stand compared to the burned stand, and in the

soil rip stand compared to the no-rip stand. Additional work on the diffusivity and on the soil

characteristics at each individual site is needed. Additional work is also need to validate and integrate

chamber and profile measurements.


Something about statistics: Tree growth from forest inventories

Melissa Eitzel, John Battles, Rob York, Jonas Knape, Perry de Valpine


Understanding tree growth as a function of tree size is important for a multitude of

applications. What variables limit growth is of central interest for many of these applications.

Trees' slow growth and long lifespans necessitate the use of any and all information to inform

these questions, and forest inventory data are an abundant source of information but are highly

complex. Observation error and multiple sources of shared variation (spatial plot effects,

temporal repeated measures, and uneven time intervals between measurements) make these data

challenging to use for growth estimation. We account for these complexities and incorporate

potential limiting factors (tree size, competition, and resource supply variables) into a hierarchical

state-space model. We estimate the diameter growth of Abies concolor (white fir) in the Sierra

Nevada of California from forest inventory data, showing that estimating such a model is feasible

in a Bayesian framework using popular Markov chain Monte Carlo tools. In this forest, tree

growth depends strongly on tree size, local population density, and individual tree quality.

Resource supply variables (elevation, topographic slope, soil type, annual deficit, and insolation)

do not have an impact on tree growth at our site.


Figure from Eitzel, Battles, York, Knape, and Valpine: Something about statistics: Tree growth from forest inventories. Explanatory variable effects on growth increment as a function of size. All plots show that growth increases with tree size in the previous year. Solid lines are the means from posteriors of parameter estimates; dashed lines are 95 % credible intervals. For all explanatory variables other than soil type, black shows growth increment for a low value of the explanatory variable (-2 standard deviations) and dark grey for a high value (+2 standard deviations). For soil type, purple is Cohasset, black is Holland, red is Holland-Bighill, blue is Holland-Musick, and green is Jocal. Credible intervals for soil type overlap a great deal and are not shown for clarity.


Arbuscular mycorrhizal colonization of giant sequoia (Sequoiadendron giganteum) in response to restoration practices

Catherine Fahey1 and Robert A. York2

1University of Florida, Gainesville, FL 2UC Center for Forestry and Department of Environmental Science, Policy, and Management, University of

California, Berkeley, CA

Interactions with soil microbiota determine the success of restoring plants to their native

habitats. The goal of our study was to understand the effects of restoration practices on

interactions of giant sequoia Sequoiadendron giganteum with arbuscular mycorrhizal (AM) fungi

(phylum Glomeromycota). Natural regeneration of Sequoiadendron is threatened by the absence

of high-severity fires that create forest canopy gaps. Generating artificial canopy gaps offers an

alternative tool for giant sequoia restoration. We investigated the impact of regeneration

practices, including: (i) sapling location within gaps, (ii) gap size, and (iii) soil substrate, on AM

fungal colonization of giant sequoia sapling roots in a native giant sequoia grove at Whitaker’s

Forest Research Station, California, USA. We found that the extent of AM fungal root

colonization was positively correlated with sapling height and light availability, which were

related to the location of the sapling within the gap and the gap size. While in saplings on ash

substrate, colonization frequency by arbuscules was higher relative to saplings on mineral soil, the

total AM fungal root colonization was similar between the substrates. A negative correlation

between root colonization by Glomeromycota and non-AM fungal species indicated antagonistic

interactions between different classes of root-associated fungi. Using DNA genotyping, we

identified six AM fungal taxa representing genera Glomus and Ambispora present in

Sequoiadendron roots. Overall, we found that AM fungal colonization of giant sequoia roots was

associated with availability of plant-assimilated carbon to the fungus rather than with the AM

fungal supply of mineral nutrients to the roots. We conclude that restoration practices affecting

light availability and carbon assimilation alter feedbacks between sapling growth and activity of

AM fungi in the roots.


Figure from Fahey and York: Arbuscular mycorrhizal colonization of giant sequoia

(Sequoiadendron giganteum) in response to restoration practices. The effect of giant sequoia sapling

position within gap on: a) total percent colonization by AM fungi subdivided into structures, and b) non-AM

fungi. Bars indicate standard error.


Aminocyclopyrochlor sequoia tolerance trials

Ed Fredrickson

Thunder Road Resources, Redding, CA

E.I. DuPont, Wilmington, DE

In the fall of 2011 a trial was established to evaluate the conifer tolerance of giant sequoia

(Sequoiadendron giganteum) to aminocyclopyrochlor (MAT 28), a new herbicide from DuPont.

The trial was established to evaluate the soil active effects of the herbicide on sequoia tolerance.

The trial was a randomized complete block design with five replications per treatment. Each

replication was one tree. Trees were pruned to roughly 3 feet above groundline. A five by ten

foot strip was sprayed with a CO2 powered backpack boom sprayer on each side of the tree bole,

taking care to avoid any foliar contact. Application volume was at ten gallons per acre at 30 psi.

The sprayer was calibrated prior to application. The boles of trees were protected during spraying

with shields to avoid uptake from freshly cut surfaces. Several rates of MAT 28 were tested and

the trial included non-treated controls. An analogous spring replication of the trial will be

installed in 2012. The trials will be evaluated in the fall of 2012 and 2013 to visually assess

conifer damage.


Examination of tree-ring development in the five mixed conifer forest species

Danny Fry1, Jen York2, Scott Stephens1, and Brandon Collins3

1Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 2UC Center for Forestry, University of California, Berkeley, Georgetown, CA 3Fires and Fuels Program, Pacific Southwest Research Station, USDA, Forest Service, Redding, CA

Dendrochronolgy-based fire history studies describe fire regime characteristics of a forest

including the fire return interval. The position of a fire scar within the annual ring has also been

widely used to estimate the season in which the fire occurred. However, it is well known that tree

ring phenology varies by many factors, yet there has not been a study examining annual ring

development to quantify this variation. In this study we will identify the timing of the onset and

cessation of earlywood and latewood growth by thermally wounding the cambium along the bole

of the same trees repeatedly through the growing season. By killing a small portion of the

cambium at set intervals we will be able to determine the stage of growth of the annual ring. We

selected three replicates of each of the five species in two compartments. In 2010, the 30 trees

were burned for 10 minutes using a propane torch on the following dates: May 20th

, June 26th

,

July 26th

, September 7th

, September 30th

, and October 29th

. A rectangular section of bark on each

tree was shaved off with an axe to facilitate heating of the cambium. The bark of one tree of each

species was shaved but not burned to serve as a control. Cross sections of the scarred area will be

collected in the summer of 2012 and taken back to the lab for processing and analysis of scar

positions. This information will contribute to the understanding of tree-ring development and

interpretation of seasonality inferred in fire history studies.

Figure from Fry, York, Stephens, and Collins: Examination of tree-ring development in the five mixed conifer forest species.


Lidar scanning for feature extraction

Kyle Holland and Gregory Biging


Laser scanners use light detection and ranging (lidar) to calculate the three-dimensional

coordinates of physical points on the surfaces of objects, called a point cloud. Inherent in the

point cloud is information about the location and shape of features such as trees, snags and

seedlings. By analyzing a time series of point cloud data and measuring changes in forest

structure over time, detailed models of complex forest dynamics can be readily created. These

models can be applied to predict changes in forest structure resulting from forest management.

Although laser scanning is relatively fast compared to traditional methods of forest measurement,

the volume of data in the point cloud presents a problem for its analysis.

The objective of this study is to automatically extract the locations and types of trees,

snags and seedlings from point cloud data using a computer. The data are obtained using a

Velodyne laser scanner positioned at multiple points in a one hectare unit of mature forest. The

point cloud is analyzed using a supervised approach where a human interpreter identifies the

locations and types of features in a subset of the data, called a training set, and a discriminant

classifier is applied to extract features in the whole point cloud.

The accuracy of the method is inferred three ways. First, cross-validation is performed by

bootstrapping the training set and observing how the number and types of identified features vary

as a result. Second, plots are randomly installed in the study area and the locations and types of

trees, snags and seedlings are measured. These measurements are compared with those produced

by the computer. Third, the study area is rescanned using the same procedure and new point

cloud data are analyzed using the computer. The measurements from these independent scans are

compared to each other.


Genetic characterization of slenders salamanders (Batrachoseps) from the Whitaker Forest

Elizabeth Jockusch

Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT

Slender salamanders of the genus Batrachoseps are endemic to the west coast of North

America, where they have radiated into 19 described species. This makes them the most speciose

clade of amphibians in western North America. Samples of Batrachoseps were collected from the

Whitaker Forest by Joseph Marshall in July, 1938, and are housed in the collection of the

Museum of Vertebrate Zoology, University of California, Berkeley. These specimens were

classified as B. attenuatus at the time, which was the only species described from California.

Since then, slender salamanders in the central Sierra Nevada have been described as three distinct

species: B. gregarius, B. regius and B. kawia. A one day survey for slender salamanders at

Whitaker Forest in May 2009 yielded a single specimen. Subsequent molecular work showed that

this specimen has mitochondrial DNA characteristic of B. regius, but nuclear genes characteristic

of B. kawia, suggesting that the two species have come into contact and hybridized in the vicinity

of Whitaker Forest. Only one other population with this combination of genes is known, from

Summit Meadow in Kings Canyon National Park. Additional amphibians and reptiles

encountered during field work were Ensatina eschscholtzii (which was abundant), Bufo boreas,

Thamnophis, Elgaria, and Sceloporus.


Biomass in sequoia vs. Sierra mixed-conifer stands

Anne E. Kelly, Paige Austin, Glenn Cajar, Michael L. Goulden

Earth System Science and Ecology and Evolutionary Biology, University of California, Irvine, CA

The forest of the mid-elevation Sierra Nevada contains the largest trees in the world,

Sequoiadendron giganteum. This forest also supports dense, large-statured stands of Abies

concolor, Pinus jeffreyi, Pinus lambertiana, and Quercus kelloggii. Our research focuses on the

question of how a Mediterranean climate with cold winters and long, dry summers can support

such enormous forests. In the Sierra National Forest, we measured biomass of 110 tC ha-1

in

average mid-elevation stands, comparable to tropical rainforest. We measured the biomass of

stands in and around Whitaker’s Forest in order to determine an upper limit on biomass that the

climatology that mid-elevation forest could support. We found 1300 tC ha-1

in a stand that

contained almost exclusively mature sequoia. Further research will be conducted to determine

productivity of these stands in order to understand why these forests are so massive.


Fungus gnats of California

Peter H. Kerr

California State Collection of Arthropods, Plant Pest Diagnostics Branch, California Department of Food &

Agriculture, Sacramento, CA

Fungus gnats (Diptera: Sciaroidea: Mycetophilidae and relatives) are an abundant and

easily collected group of flies, which depend on fungi for their larval development. Many fungus

gnat species appear restricted to hosts of particular ecological or systematic groups and infestation

rates can be high in certain fungal lineages. Exceedingly few studies have been done to

understand fungus gnat biodiversity, larval morphology, host range, or co-evolution with host

macrofungi in the California Floristic Province. Malaise traps were set to capture fungus gnat

adults at Whitaker’s Research Forest between June 3 and October 8, 2010. Twenty-eight genera of

Mycetophilidae were recovered; these include: Acnemia, Allodia, Allodiopsis, Azana, Boletina,

Brevicornu, Coelopthinia, Cordyla, Docosia, Dynatosoma, Dziedzickia, Exechia, Exechiopsis,

Greenomyia, Hadroneura, Megophthalmidia, Mycetophila, Mycomya, Neuratelia, Phronia,

Phthinia, Rymosia, Sceptonia, Stigmatomeria, Synapha, Tetragoneura, Trichonta, and Zygomyia.

Specimens are now being processed at the species level. Both Azana species were new and

recently described (Kerr, P.H. (2010) New Azana species from Western North America (Diptera:

Mycetophilidae), Zootaxa 2397, 1–14). Also recovered were keroplatids Euceroplatus sp.,

Macrocera spp., and Orfelia spp., and Diadocidia stanfordensis (Diadocidiidae). Of special note

was the capture of an unusual sciaroid of an undescribed genus; this taxon is currently the focus of

an upcoming taxonomic treatment. All material is deposited at the California State Collection of

Arthropods (Sacramento) and will be used in subsequent taxonomic and diversity studies.


The burning QuKe question

Kevin Krasnow and Scott Stephens


Study objectives:

The main objective of this study was longitudinal monitoring of post treatment mortality

by species, treatment, and size class in the Fire and Fire Surrogate (FFS) study at Blodgett

Research Forest from plot tree census data from pre-treatment (2001), one year post treatment

(2003), and seven years post treatment (2009). Additionally, we examined seedling establishment

data from four years post treatment (2006), and compared post fire vegetation effects from the

2002 FFS fires to similar prescribed fires burned by Kauffman and Martin in 1983 and 1984 at

Blodgett. The focal species in this analysis was black oak (Quercus Kelloggii) due to high

morality rates observed in the fire treatments.

Methods:

We longitudinally tracked each live tree measured in the 2001 pre-treatment census to

monitor mortality occurring on or before the 2003 and 2009 post-treatment re-measures.

Masticated or harvested trees were removed from the analysis. We assessed how many trees of

each species in each size class (all trees above 2.5 cm dbh, 2.5-25 cm dbh, 25-51 cm dbh, 51-76

cm dbh, and dbh above 76 cm) that were alive in 2001 were dead in 2003 (Kobziar et al. 2006)

and in 2009. Cumulative mortality rates were calculated for 2003 and 2009. Top-killed, re-

sprouting oaks were classified as dead because the re-measurement in 2009 classified these trees

as dead.

Results:

Significant delayed mortality was observed in all treatments for most tree species (see

figure 1). Black oak showed the highest mortality rate seven years after treatment in all

treatments (excluding the controls) for all trees over 2.5 cm dbh: Mech + fire = 63.2%, Mech only

= 15.6 %, Fire only = 54.8 %. Treatments utilizing fire (Mech + Fire and Fire only) showed the

highest tree mortality levels for all tree species and especially black oak. In the fire treatments

black oaks showed the highest mortality rates in every size class where it was present (except the

51-76 cm dbh class in the Mech + Fire treatment). These findings are in stark contrast to the low


level of mortality observed by Kauffman and Martin in 1983-84 prescribed fires at Blodgett: “All

tree-sized California black oaks and tanoaks survived fire, and many produced root crown sprouts

even though they were not top-killed” (Kauffman and Martin 1990).

When seedling densities measured in 2006 were examined (Moghaddas et al. 2008), it was

found that black oak showed an opposite response to fire than did it’s neighboring conifers. All

conifers measured (cade, abco, pila, pipo, psme) showed a significant increase in seedling density

4 years after treatment in the Fire only and Fire + Mech treatments. Conversely, black oak

showed a significant decline in seedling density in both of the fire treatments.

Discussion:

These findings underscore how important long-term monitoring is for Sierran trees that

may take many years to die from management or natural disturbance. Of particular importance is

the “double whammy” served to black oaks in the fire treatments: significant overstory mortality

(especially in the large size classes) combined with reduced seedling density. This casts

uncertainty on the future ecological role of black oaks in the fire treatments areas. In the future,

managers many decide to forgo fire treatments in high oak density areas, to remove fuel from the

base of large oaks before burning, and/or to replant oaks after fire treatments.

References:

Kauffman, J. and R. Martin. 1990. Sprouting shrub response to different seasons and fuel

consumption levels of prescribed fire in Sierra Nevada mixed conifer ecosystems. Forest

Science 36:748-764.

Kobziar, L., J. Moghaddas, and S. L. Stephens. 2006. Tree mortality patterns following prescribed

fires in a mixed conifer forest. Canadian Journal of Forest Research 36:3222-3238.

Moghaddas, J. J., R. A. York, and S. L. Stephens. 2008. Initial response of conifer and California

black oak seedlings following fuel reduction activities in a Sierra Nevada mixed conifer

forest. Forest Ecology and Management 255:3141-3150.


Figure from Krasnow and Stephens: The burning QuKe question.


Closing the peroxy acetyl nitrate budget: observations of acyl peroxy nitrates (PAN, PPN, and MPAN) during BEARPEX 2007

B.W. LaFranchi1, G. M.Wolfe2, J. A. Thornton3, S. A. Harrold3, E. C. Browne1, K. E. Min4, P. J. Wooldridge1, J. B. Gilman5, W. C. Kuster5, P. D. Goldan5, J. A. de Gouw5, M. McKay6,*, A. H. Goldstein6, X. Ren7,**, J. Mao7,***, and R. C. Cohen1,4

1Department of Chemistry, University of California, Berkeley, CA 2Department of Chemistry, University of Washington, Seattle, WA 3Department of Atmospheric Sciences, University of Washington, Seattle, WA 4Department of Earth and Planetary Science, University of California, Berkeley, CA 5NOAA/ESRL Chemical Sciences Division, Boulder, CO 6Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 7Department of Meteorology, Penn State University, University Park, PA *now at: California Air Resources Board, Sacramento, CA **now at: Rubenstein School of Marine and Atmospheric Science, University of Miami, Miami, FL ***now at: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA

Acyl peroxy nitrates (APNs, also known as PANs) are formed from the oxidation of

aldehydes and other oxygenated VOC (oVOC) in the presence of NO2. There are both

anthropogenic and biogenic oVOC precursors to APNs, but a detailed evaluation of this chemistry

against observations has proven elusive. Here we describe measurements of PAN, PPN, and

MPAN along with the majority of chemicals that participate in their production and loss,

including OH, HO2, numerous oVOC, and NO2. Observations were made during the Biosphere

Effects on AeRosols and Photochemistry Experiment (BEARPEX 2007) in the outflow of the

Sacramento urban plume. These observations are used to evaluate a detailed chemical model of

APN ratios and concentrations. We find that the ratios of APNs are nearly independent of the loss

mechanisms and thus an especially good test of our understanding of their sources. We show that

oxidation of methylvinyl ketone, methacrolein, methyl glyoxal, biacetyl and acetaldehyde are all

significant sources of the PAN + peroxy acetyl (PA) radical reservoir, accounting for 26%, 2%,

7%, 20%, and 45%, of the production rate on average during the campaign, respectively. At high

temperatures, when upwind isoprene emissions are highest, oxidation of non-acetaldehyde PA

radical sources contributes over 60% to the total PA production rate, with methylvinyl ketone

being the most important of the isoprene-derived sources. An analysis of absolute APN

concentrations reveals a missing APN sink that can be resolved by increasing the PA + 6RO2 rate

constant by a factor of 3.


Observations of the temperature dependent response of ozone to NOx reductions in the Sacramento, CA urban plume

B.W. LaFranchi1,*, A. H. Goldstein2,3, and R. C. Cohen1,4

1Department of Chemistry, University of California, Berkeley, CA 2Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 3Department of Civil and Environmental Engineering, University of California, Berkeley, CA 4Department of Earth and Planetary Science, University of California, Berkeley, CA *now at: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA

Observations of NOx in the Sacramento, CA region show that mixing ratios decreased by

30% between 2001 and 2008. Here we use an observation-based method to quantify net ozone

(O3) production rates in the outflow from the Sacramento metropolitan region and examine the O3

decrease resulting from reductions in NOx emissions. This observational method does not rely on

assumptions about detailed chemistry of ozone production, rather it is an independent means to

verify and test these assumptions. We use an instantaneous steady-state model as well as a

detailed 1-D plume model to aid in interpretation of the ozone production inferred from

observations. In agreement with the models, the observations show that early in the plume, the

NOx dependence for Ox (Ox = O3 + NO2) production is strongly coupled with temperature,

suggesting that temperature-dependent biogenic VOC emissions and other temperature-related

effects can drive Ox production between NOx-limited and NOx-suppressed regimes. As a result,

NOx reductions were found to be most effective at higher temperatures over the 7 year period. We

show that violations of the California 1-h O3 standard (90 ppb) in the region have been decreasing

linearly with decreases in NOx (at a given temperature) and predict that reductions of NOx

concentrations (and presumably emissions) by an additional 30% (relative to 2007 levels) will

eliminate violations of the state 1 h standard in the region. If current trends continue, a 30%

decrease in NOx is expected by 2012, and an end to violations of the 1 h standard in the

Sacramento region appears to be imminent.


Examining variability in Douglas-fir growth at a continental scale

Christina Lyons-Tinsley1 and David L. Peterson2

1Fire and Mountain Ecology Laboratory, School of Forest Resources, University of Washington, Seattle, WA 2 USDA Forest Service, Pacific Northwest Research Station, Seattle, WA

Tree life-history processes like establishment, growth, and mortality are partially

controlled by climate. Even relatively small shifts in climate can influence these processes and

may result in shifts of species distributions. Climate change models that address ecosystem

impacts simulate these distribution shifts at coarse spatial scales. However, this information lacks

utility for resource managers who operate at finer resolutions. Tree growth rates serve as an

alternative method of predicting climate effects on trees. Coniferous trees, for example Douglas-

fir, can record changes in growth that relate to climate. These Douglas-firs have radial growth

rings that express the spatial and temporal variability in tree growth and climate sensitivity. Past

growth fluxes can provide early indications of climate change effects on trees. To better

understand the effects of future climate on Douglas-fir however, more studies need to address

climate-growth interactions across the entire species range. We are investigating the climate-

growth interaction of Douglas-fir across its entire range in North America. The study is divided

into two parts. First, we are obtaining growth data from Douglas-fir in the central and southern

parts of its range that have not been previously sampled, including mountains in Oregon,

California, Arizona, New Mexico, Utah, Colorado, Wyoming, Idaho, and Montana. Second, we

are collaborating with scientists in Canada and Mexico to conduct a synthesis of climate-growth

interactions across the entire North American range of Douglas-fir.


Measuring up to managers' needs: quantifying the persistence of a fuel reduction treatment in a giant sequoia-mixed conifer forest

Mary Mayeda1 and Robert York2

1USDA Forest Service 2Center for Forestry and Department of Environmental Science, Policy, and Management, University of California,

Berkeley, CA

It is now widely accepted that fuels reduction treatments, including those that mechanically remove

understory trees, are needed to reduce the increasing fire hazard in the western U.S., but a time line as to

how often a manipulation area needs to be re-treated is still largely unavailable. This study resampled four

20-acre permanent plots established in 1964 at Whitaker’s Forest, adjacent to Kings Canyon National Park.

The objectives of this study were to judge the lasting effectiveness of a thin from below treatment coupled

with the piling and burning of all slash as well as ground and surface fuels in relation to stand structure and

fuel loading. Changes in tree (>4.5 feet tall) and seedling (<4.5 feet) density, diameter class distribution,

and ground and surface fuel loading was compared across sample dates and between treated and control

plots. A significant increase in giant sequoia density was found in treated plots, as well as an encouraging

increasing trend in sugar pine densities. White fir densities slightly increased since the last sample date in

1967. Other tree species showed no significant difference in density trends from control plots. Seedling

and basal area data was too variable for any effectual data analysis, and there was no strong agreement

between the treated plots in diameter class distribution. Ground and surface fuel loading on treated plots

has been restored to dangerous levels, despite the removal of 12% of original fuel loading during

treatment. Overall, this treatment needs to be re-implemented at a shorter interval than 43 years to reduce

the fire hazard.


A B C

D E F

Figure from Mayeda and York: Measuring up to managers' needs: quantifying the persistence of a fuel reduction treatment in a giant sequoia-mixed conifer forest. Tree density (trees per acre) shown for all trees >4.5 feet tall for individual species – (A) incense-cedar, (B) sugar pine, (C) giant sequoia, (D) white fir, (E) ponderosa pine, and (F) black oak. Data was averaged from 1/10

th acre subplots for all

treated and control plots.


Evidence for unusual peroxy nitrates and their atmosphere-biosphere exchange

Min, Kyung-Eun1, Pusede, S. E.2, Browne, E. C.2, LaFranchi, B. W.3, Lee L.2, Wooldridge, P. J.2, Wolfe, G. M.4,5, Harrold, S. A.4, Thornton J. A.4, Park, J.-H.6,

Weber, R.J.6, Goldstein, A.H.6, and Cohen, R. C.1,2

1. Department of Earth and Planetary Science, University of California, Berkeley, CA

2. Department of Chemistry , University of California at Berkeley, CA

3. Lawrence Livermore National Lab, Center for Accelerator Mass Spectrometry (CAMS), Livermore, CA

4. Department of Atmospheric Sciences, University of Washington, Seattle, WA

5. Department of Chemistry, University of Wisconsin, Madison, WI

6. Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA

Biosphere and atmosphere exchange of nitrogen oxides remains a subject poorly

constrained by observations. We report simultaneous observations of vertical gradients and eddy-

covariance fluxes of total peroxy nitrates(ΣPNs), and speciated acyl peroxy nitrates(APNs),

including peroxyacetyl nitrate (PAN), peroxymethacryloyl nitrate (MPAN), and peroxypropionyl

nitrate (PPN) obtained over a ponderosa pine plantation in the Sierra Nevada Mountains of

California during the Biosphere Effects on AeRosols and Photochemistry Experiment

(BEARPEX, June 15 to July 30, 2009). Comparison of fluxes of ΣPNs (measured by TD-LIF) and

APNs (measured by TD-CIMS) and simultaneous gradient of the same chemicals and their

correlations with temperature, photosynthetically active radiation (PAR) and biogenic volatile

organic compound (BVOC) concentrations, provide evidence for an unusual peroxynitrate formed

within the forest canopy. Reasonable candidate precursors (after more than one

oxidation/fragmentation event) include sesquiterpenes, methyl chavicol, pinonaldehyde, and

nopinone or similar molecules.

To examine the possibility further, we studied peroxy nitrate formation from beta-

caryophyllene ozonolysis in the presence of NO2 using TD-LIF and thermal dissociation gas

chromatography laser induced fluorescence (TD-GC-LIF) instrument.


Flux-gradient relationships of nitrogen oxides over a ponderosa pine plantation during BEARPEX-2009

Min, Kyung-Eun1, Pusede, S. E.2, Browne, E. C.2, LaFranchi, B. W.3, Wooldridge, P. J.2, and Cohen, R. C.1,2

1. Department of Earth and Planetary Science, University of California, Berkeley, CA

2. Department of Chemistry, University of California, Berkeley, CA

3. Lawrence Livermore National Lab, Center for Accelerator Mass Spectrometry (CAMS), Livermore, CA

During the Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX, June 18

to July 30, 2009), gradients and eddy covariance fluxes of NO2, total peroxy nitrates (ΣPNs), total

alkyl nitrates (ΣANs), and nitric acid (HNO3) were simultaneously monitored from above a

ponderosa pine plantation in the Sierra Nevada Mountains of California using thermal

dissociation - laser induced fluorescence (TD-LIF). NO gradient and flux measurements were

made using a home-built O3 chemiluminescence instrument. We report upward fluxes of NO and

NO2, downward fluxes of ΣPNs and HNO3, and a bidirectional ΣANs flux during the daytime.

Fluxes of NO2 and HNO3 are qualitatively explained by a simple flux-gradient relationship (the

flux and gradient have the same sign); however canopy influenced photochemistry must be

considered in a more quantitative description of the fluxes. Moreover, the fluxes and gradients of

ΣANs, ΣPNs, and NO are only consistent when considered in the context of their chemistry.


Gaseous elemental mercury emissions and CO2 respiration rates in terrestrial soils under controlled aerobic and anaerobic laboratory

conditions

Daniel Obrist , Xavier Faïn, and Carsen Berger

Desert Research Institute, Division of Atmospheric Sciences, Reno, NV

Mercury (Hg) levels in terrestrial soils are linked to the presence of organic carbon (C).

Carbon pools are highly dynamic and subject to mineralization processes, but little is known

about the fate of Hg during decomposition. This study evaluated relationships between gaseous

Hg emissions from soils and carbon dioxide (CO2) respiration under controlled laboratory

conditions to assess potential losses of Hg to the atmosphere during C mineralization. Results

showed a linear correlation (r2=0.49) between Hg and CO2 emissions in 41 soil samples, an effect

unlikely to be caused by temperature, radiation, different Hg contents, or soil moisture.

Stoichiometric comparisons of Hg/C ratios of emissions and underlying soil substrates suggest

that 3% of soil Hg was subject to evasion. Even minute emissions of Hg upon mineralization,

however, may be important on a global scale given the large Hg pools sequestered in terrestrial

soils and C stocks. We induced changes in CO2 respiration rates and observed Hg flux responses,

including inducement of anaerobic conditions by changing chamber air supply from N2/O2 (80%

and 20%, respectively) to pure N2. Unexpectedly, Hg emissions almost quadrupled after O2

deprivation while oxidative mineralization (i.e., CO2 emissions) was greatly reduced. This Hg

flux response to anaerobic conditions was lacking when repeated with sterilized soils, possibly

due to involvement of microbial reduction of Hg2+ by anaerobes or indirect abiotic effects such

as alterations in soil redox conditions. This study provides experimental evidence that Hg

volatilization, and possibly Hg2+ reduction, is related to O2 availability in soils from two Sierra

Nevada forests. If this result is confirmed in soils from other areas, the implication is that Hg

volatilization from terrestrial soils is partially controlled by soil aeration and that low soil O2

levels and possibly low soil redox potentials lead to increased Hg volatilization from soils.


Terrestrial mercury (Hg) surface reservoirs: magnitude, spatial patterns, fate, and re-emission potential to the atmosphere

Daniel Obrist


Terrestrial ecosystems are strong natural reservoirs that retain the bulk of atmospheric Hg

deposition. As a result, a long-term legacy of past and present Hg pollution is sequestered in

surface litter and soil pools. Hg shows a particular affinity to—and hence tends to accumulate

in—terrestrial organic C pools. We present results from a comprehensive five-year investigation

where we quantified concentrations and pool size distribution of terrestrial reservoirs of Hg in

forests, and their relationships to organic C to assess the degree to which C determines net

retention of Hg. A special emphasis is placed upon fate of terrestrial Hg reservoirs, including

losses though wildfires, C mineralization, the potential for re-emissions back to the atmosphere,

and sensitivity to climate change.

Results show that continental-scale spatial distribution of Hg in soils and litter is strongly

related to that of C, and that Hg levels (concentrations and pool sizes of total Hg, as well as

methylated Hg) increase with higher latitude. We calculate that at a global scale as much as 4.5 x

106 Mg of Hg is sequestered in terrestrial surface reservoirs. In Sierra Nevada pine forests, total

ecosystem-level Hg pools (aboveground plus belowground [0 – 40 cm]) ranged from 44 to 72 g

Hg ha-1

(Figure 1). Experimental studies and field observations to address fate of Hg show that (i)

fires lead to up-to-complete Hg losses from biomass in either gaseous elemental or particulate-

bound form; however, no effects is seen on total ecosystem-level stocks in Sierra Nevada sites

because the main bulk of Hg is located in soils (>94%; Figure 1) which is not depleted upon

wildfires or prescribed burning; (ii) litter decomposition (Figure 2) can lead to evasion losses (or

re-emissions) of Hg of 5 to 23% of Hg mass after 18 month of incubation; in Jeffrey Pine litter

collected from Blodgett forest, however, Hg losses were not statistically significant after 18

months, which we attribute to slow decomposition rates of this litter type; (iii) in contrast, re-

emission losses of Hg from soils to the atmosphere upon C mineralization are small (<3% of Hg

bound to C) and likely driven by surface processes; (iv) in deeper soils, gaseous soil pore Hg

concentrations are mostly below atmospheric levels and decoupled from CO2 concentration

profiles, indicating that the soil matrix may be an active sink for gaseous Hg rather and a strong

diffusion-driven source.


Figure 1 from Obrist: Terrestrial mercury (Hg) surface reservoirs: magnitude, spatial patterns, fate, and re-emission potential to the atmosphere. Total ecosystem-level pools of Hg and carbon in four Sierra Nevada pine forest stands. Two stands were located in Little Valley east of Lake Tahoe, with one site previously burned by a wildfire. Two sites are located north of Truckee, CA, with one site affected by prescribed burning. From Obrist et al., Biogeosciences, 2009.

Little Valley site Truckee site

Figure 2 from Obrist: Terrestrial mercury (Hg) surface reservoirs: magnitude, spatial patterns, fate, and re-emission potential to the atmosphere. Litter incubation study to assess gaseous losses (re-emissions) of Hg to the atmosphere during litter decomposition over 18 months. Litter types included deciduous and coniferous litter from four forest sites, including pine litter collected from Blodgett forest. Field control samples were decomposed in the field. From Pokharel and Obrist, Biogeosciences, 2011.


Interactions between planting density and tree architecture on leaf area index development in giant sequoia

Kevin L. O’Hara1 and Robert A. York2

1Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 2UC Center for Forestry and Department of Environmental Science, Policy, and Management, University of


Development of leaf area index (LAI) in even-aged stands is generally assumed to develop

to a maxima controlled by site resources. For a given site, the rate at which the LAI approaches

this maxima is largely controlled by the initial stand density. Stands planted at high densities will

approach the maximum more rapidly than stands planted at low densities. All stands on a given

site approach the same maxima and essentially converge to this level over time. We tested this

“convergence model” using the giant sequoia spacing study at Blodgett Forest. This spacing

study compares nine spacings ranging from 2.1 to 6.1 meters and was established in 1989.

We used a “branch summation” approach to developing sapwood leaf area relationships to

predict individual tree leaf area. This method involves measuring the branch caliper of all

branches, developing allometric relationships to predict branch leaf area from branch caliper, and

finally developing relationships of tree leaf area (sum of branch leaf areas) to sapwood area at

crown base. This approach worked very well for the 15 young giant sequoia trees sampled on

Blodgett Forest. In the spacing study, tree measurements from age 4 to age 22 were used to

estimate tree leaf area. These leaf areas were then summed by plot and divided by plot area to

estimate LAI. We also used crown measurements in years 10, 16 and 22 to evaluate crown

architecture of individual trees.

Results indicate the development of LAI in the giant sequoia spacing study is not

following the convergence model through age 22 (Figure 1). Instead, the highest densities have

the highest LAI, and there is no evidence of any convergence for at least several decades. We

used ratios of crown length to crown width (CL:CW) to examine crown architecture. Young giant

sequoia trees have a very narrow, conical crown form with CL:CW ratios of about 14 at age 22

for all spacings. This suggests that giant sequoia may be unable to fully occupy available growing

space at wide spacings.

Compared to other species, giant sequoia has very low crown plasticity or limited ability

to adjust crown form to compete for available growing space. When planted at wide spacings, or

following thinning, this species would be very slow to occupy unused growing space compared to


most other conifers. This suggests that giant sequoia may have longer periods of brush

competition during early stand development or after thinning treatments. Branch retention may

also be greater because lower branches are less likely to be shaded in stands of trees with narrow

crowns. These results do not suggest the convergence model is incorrect. Instead, they imply the

convergence in giant sequoia LAI may be very late for wide spacings.

Age

2 4 6 8 10 12 14 16 18 20 22 24

LA

I

0

2

4

6

82.1

6.1

2.4

3.0

2.7

3.7

4.3

4.9

5.5

Figure from O’Hara and York: Interactions between planting density and tree architecture on leaf area index development in giant sequoia. LAI trajectories for nine spacing treatments as indicated by spacings (meters) to the right of each LAI trajectory.


Estimating BVOC (Biogenic Volatile Organic Compound) emissions by flux-gradient relationship during BEARPEX 2009

Jeong-Hoo Park1, Silvano Fares1, Robin Weber1, and Allen H. Goldstein1, 2

1 Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 2 Department of Civil and Environmental Engineering, University of California, Berkeley, CA

During summer 2009 an intensive field campaign (Biosphere Effects on AeRosols and

Photochemistry EXperiment - BEARPEX) took place in Blodgett Forest, a Ponderosa pine forest

in the Sierra Nevada Mountains of California. A PTR-MS (Proton Transfer Reaction – Mass

Spectrometry) was used to measure 19 compounds (masses) including methanol, isoprene + MBO

(2-Methyl-3-butene-2-ol), monoterpenes, sesquiterpenes, and some oxygenated BVOCs at 5

heights of a vertical gradient from the forest floor to above the canopy. Fluxes of the 3 dominant

BVOCs were measured above the canopy with the Eddy covariance technique. For determining

canopy scale fluxes of the other compounds, we applied the flux-gradient similarity approach (K-

theory). K was calculated by dividing flux measurements by vertical gradients then multiplied by

the gradients of each compound to compute the fluxes. Fluxes will be presented for all species and

compared to historical measurements from the same site. MBO was the dominant emission

observed followed by methanol, monoterpenes, acetone, and acetaldehyde.


Influence of bio-mass & fire reduction techniques on soil strength in a Sierra Nevada mixed conifer forest

Jennifer Podvin, Amara Johnson, and Robert A. York

UC Center for Forestry and Department of Environmental Science, Policy, and Management, University of


Tree plantations are often high density, uniform forests where trees are roughly the same

size. Plantations are important for the resources they provide both to ecosystems and society—

both public and private, yet plantations can be at high risk of damage from wildfire due to the

increased fire intensity observed in plantations.

In this study, two methods which have proved to be helpful in reducing wildfire risk will

be used: biomass thinning and mastication. Biomass harvests involve thinning the forest and using

the excess wood to generate renewable electricity-- which also has the added potential to not only

reduce fire intensity but create space for more fire resistant trees to grow more quickly. The

second method, mastication, involves chipping the thinned trees in place. Mastication may result

in higher long-term productivity, but may not be as effective in the reduction of short term fire

hazard. With both methods, there is concern that the equipment used to administer these

treatments will increase soil compaction on forest floors, leading to decreased forest productivity.

The objective of this project was to measure potential study areas to assess their potential for

inclusion into the long term study.

The results of our initial soil strength readings indicate that while there is no difference in

the upper soil profile between compartments there is a significant difference in soil strength

among the compartments overall. Therefore we can conclude that most of the variability in soil

strength between compartments occurs in the deep soils. Most of the soil compaction that is likely

to occur with bio-mass harvests or mastication is expected to occur in the upper soil profile;

therefore these compartments are likely to be acceptable for the overall study with the exception

of compartment 280 which stood out with exceptionally high soil strength.


Fate of mercury in tree litter during decomposition

A. K. Pokharel and D. Obrist


We performed a controlled laboratory litter incubation study to assess changes in dry

mass, carbon (C) mass and concentration, mercury (Hg) mass and concentration, and

stoichiometric relations between elements during decomposition. Twenty-five surface litter

samples each, collected from four forest stands, were placed in incubation jars open to the

atmosphere, and were harvested sequentially at 0, 3, 6, 12, and 18 months. Using a mass balance

approach, we observed significant mass losses of Hg during decomposition (5 to 23% of initial

mass after 18 months), which we attribute to gaseous losses of Hg to the atmosphere through a

gas-permeable filter covering incubation jars. Percentage mass losses of Hg generally were less

than observed dry mass and C mass losses (48 to 63% Hg loss per unit dry mass loss), although

one litter type showed similar losses. A field control study using the same litter types exposed at

the original collection locations for one year showed that field litter samples were enriched in Hg

concentrations by 8 to 64% compared to samples incubated for the same time period in the

laboratory, indicating strong additional sorption of Hg in the field likely from atmospheric

deposition. Solubility of Hg, assessed by exposure of litter to water upon harvest, was very low

(<0.22 ng Hg g−1 dry mass) and decreased with increasing stage of decomposition for all litter

types. Our results indicate potentially large gaseous emissions, or re-emissions, of Hg originally

associated with plant litter upon decomposition. Results also suggest that Hg accumulation in

litter and surface layers in the field is driven mainly by additional sorption of Hg, with minor

contributions from “internal” accumulation due to preferential loss of C over Hg. Litter types

showed highly species-specific differences in Hg levels during decomposition suggesting that

emissions, retention, and sorption of Hg are dependent on litter type.


Measurement of atmospheric nitrous acid at Blodgett Forest during BEARPEX 2007

X. Ren1, H. Gao2, X. Zhou2,3, J. D. Crounse4, P. O. Wennberg5,6, E. C. Browne7, B. W. LaFranchi7,*, R. C. Cohen7,8, M. McKay9,**, A. H. Goldstein9, and J. Mao10,***

1Rosenstiel School of Marine and Atmospheric Science, University of Miami, FL 2Department of Environmental Health Sciences, State University of New York, Albany, NY 3Wadsworth Center, New York State Department of Health, Albany, NY 4Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 5Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, CA 6Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 7Department of Chemistry, University of California, Berkeley, CA 8Department of Earth and Planetary Science, University of California, Berkeley, CA 9Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 10Department of Meteorology, Pennsylvania State University, University Park, PA *now at: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA **now at: California Air Resources Board, Sacramento, CA ***now at: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA

Abstract. Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH) in

the lower troposphere. Understanding HONO chemistry, particularly its sources and contribution

to HOx (=OH+HO2) production, is very important for understanding atmospheric oxidation

processes. A highly sensitive instrument for detecting atmospheric HONO based on aqueous long

path absorption photometry (LOPAP) was deployed in the Biosphere Effects on Aerosols and

Photochemistry Experiment (BEARPEX) at Blodgett Forest, California in late summer 2007. The

median diurnal variation shows minimum HONO levels of about 20–30 pptv during the day and

maximum levels of about 60–70 pptv at night, a diurnal pattern quite different from the results at

various other forested sites. Measured HONO/NO2 ratios for a 24-h period ranged from 0.05 to

0.13 with a mean ratio of 0.07. Speciation of reactive nitrogen compounds (NOy) indicates that

HONO accounted for only ~3% of total NOy. However, due to the fast HONO loss through

photolysis, a strong HONO source (1.59 ppbv day−1

) existed in this environment in order to

sustain the observed HONO levels, indicating the significant role of HONO in NOy cycling. The

LOPAP HONO measurements were compared to the HONO measurements made with a

Chemical Ionization Mass Spectrometer (CIMS) over a three-day period. Good agreement was

obtained between the measurements from the two different techniques. Using the expansive suite

of photochemical and meteorological measurements, the contribution of HONO photolysis to HOx

budget was calculated to be relatively small (6%) compared to results from other forested sites.

The lower HONO mixing ratio and thus its smaller contribution to HOx production are attributed

to the unique meteorological conditions and low acid precipitation at Blodgett Forest. Further


studies of HONO in this kind of environment are needed to test this hypothesis and to improve

our understanding of atmospheric oxidation and nitrogen budget.


A relaxed eddy accumulation system for measuring vertical fluxes of nitrous acid

X. Ren1,*, J. E. Sanders1, A. Rajendran1,**, R. J. Weber2, A. H. Goldstein2, S. E. Pusede3, E. C. Browne3, K.-E. Min3, and R. C. Cohen3,4

1Resenstiel School of Marine and Atmospheric Science, Unirversity of Miami, FL 2Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 3Department of Chemistry, University of California, Berkeley, CA 4Department of Earth and Planetary Science, University of California, Berkeley, CA *now at: Air Resources Laboratory, National Oceanic and Atmospheric Administration, Silver Spring, MD **now at: Department of Epidemiology and Public Health, University of Miami, FL

A relaxed eddy accumulation (REA) system combined with a nitrous acid (HONO)

analyzer was developed to measure atmosperhic HONO vertical fluxes. The system consists of

three major components: (1) a fast-response sonic anemometer measuring vertical wind velocity

and air temperature, (2) a fast-response controlling unit separating air motions into updraft and

downdraft samplers by the sign of vertical wind velocity, and (3) a highly sensitive HONO

analyzer based on aqueous long path absorption photometry measuring HONO concentations in

these updrafts and downdrafts. A dynamic velocity threshold (±0.5σw, where σw is a standard

deviation of the vertical wind velocity) was used for valve switching determined by the running

means and standard deviations of the vertical wind velocity. Using measured temperature as a

tracer and the average values from two field deployments, the flux proportionality coefficient, β,

was determined to be 0.42 ± 0.02, in good agreement with the theoretical estimation. The REA

system was deployed in two ground-based field studies. In the California Research at the Nexus

of Air Quality and Climate Change (CalNex) study in Bakersfield, California in summer 2010,

measured HONO fluxes appeared to be upward during the day and were close to zero at night.

The upward HONO flux was highly correlated to the product of NO2 and solar radiation. During

the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX 2009) at Blodgett

Forest, California in July 2009, the overall HONO fluxes were small in magnitude and were close

to zero. Causes for the differences in HONO fluxes in the two different environments are briefly

discussed.


Aircraft measurements of the impacts of pollution aerosols on clouds and precipitation over the Sierra Nevada

Daniel Rosenfeld,1 William L. Woodley,2 Duncan Axisa,3 Eyal Freud,1 James G. Hudson,4 and Amir Givati1

1 Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel 2 Woodley Weather Consultants, Littleton, CO 3 Seeding Operation and Atmospheric Research, Plains, TX 4 Desert Research Institute, University of Nevada, Reno, NV

Recent publications suggest that anthropogenic aerosols suppress orographic precipitation

in California and elsewhere. A field campaign (SUPRECIP: Suppression of Precipitation) was

conducted to investigate this hypothesized aerosol effect. The campaign consisted of in situ

aircraft measurements of the polluting aerosols, the composition of the clouds ingesting them, and

the way the precipitation-forming processes are affected. SUPRECIP was conducted during

February and March of 2005 and February and March of 2006. The flights documented the

aerosols and orographic clouds flowing into the central Sierra Nevada from the upwind densely

populated industrialized/urbanized areas and contrasted them with the aerosols and clouds

downwind of the sparsely populated areas in the northern Sierra Nevada. SUPRECIP found that

the aerosols transported from the coastal regions are augmented greatly by local sources in the

Central Valley resulting in high concentrations of aerosols in the eastern parts of the Central

Valley and the Sierra foothills. This pattern is consistent with the detected patterns of suppressed

orographic precipitation, occurring primarily in the southern and central Sierra Nevada, but not in

the north. The precipitation suppression occurs mainly in the orographic clouds that are triggered

from the boundary layer over the foothills and propagate over the mountains. The elevated

orographic clouds that form at the crest are minimally affected. The clouds are affected mainly

during the second half of the day and the subsequent evening, when solar heating mixes the

boundary layer up to cloud bases. Local, yet unidentified nonurban sources are suspected to play a

major role.


Update on the status of the goldspotted oak borer in California

Steven J. Seybold1 and Tom W. Coleman2

1USDA Forest Service, Pacific Southwest Research Station, Chemical Ecology of Forest Insects, Ecosystem Function

and Health Program, Davis, CA 2USDA Forest Service, Forest Health Protection, San Bernardino, CA

The goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae) (Fig.

1) is one of many indigenous exotic species of forest insects that have been detected recently in

North America (Dodds et al., 2010). This flatheaded borer mines in the phloem and surface of the

xylem of red oaks in Arizona and California. An invasive population in San Diego County has

killed an estimated 22,171 trees (coast live oak, Quercus agrifolia; California black oak, Q.

kelloggii; and canyon live oak, Q. chrysolepis). A sampling survey revealed that 61% of the large

diameter oaks are infested and 13% have been killed in the County. Aerial survey analyses of tree

mortality revealed that the population of A. auroguttatus has appeared to have expanded about 50

km over the past nine years from the hypothetical point of introduction near the communities of

Pine Valley and Descanso in San Diego Co. A 2009-2011 trapping survey that used unbaited

purple prism-shaped sticky traps shows trap catches only in the southern two-thirds of San Diego

Co. and negative catches all the way to the northern terminus of the survey in Compartment 570

of Blodgett Forest. The four survey traps at Blodgett Forest (both lime green- and purple-colored)

have allowed us to collect a wide array of flatheaded borers of other species that will increase our

understanding of the biodiversity of the group on the Forest.

Research is proceeding on the improvement of the trapping tool by investigating the

impact of trap color, the efficacy of clear plastic sticky stem traps, and various baits based on oak

volatiles. In 2012 we will investigate the potential cross-attraction of a new sex pheromone

isolated from the congeneric emerald ash borer, A. planipennis in eastern North America.

Assessing the risk of A. auroguttatus in California and surrounding states is proceeding by

evaluating the host range of the beetle, its tolerance of cold temperatures, and its capacity to

disperse by flight. In San Diego Co., the adults begin to disperse in mid-May, reach a period of

maximum flight activity in late June and early July, and generally cease to disperse by early

September. A few beetles have been trapped on purple traps as late as early November. The

major concern in managing the further invasiveness of this pest is the temptation of San Diego

Co. landowners and arborists to convert the dying oaks into firewood for sale outside of the

County. Investigations of the efficacy of various treatments of infested wood (solarization,


debarking, grinding) were discussed during the presentation, as was the concept for a “firewood

bank,” i.e., a manned storage facility in southern San Diego Co. that trades dried and “disinfested”

firewood for green infested material. Proactive behavior by regulatory and resource personnel at

the State and County levels will be imperative to slow the spread of the goldspotted oak borer

northward in California.

Suggested References:

Coleman, T.W., Grulke, N.E., Daly, M., Godinez, C., Schilling, S.L., Riggan, P.J., Seybold, S.J.,

2011a. Coast live oak, Quercus agrifolia, susceptibility and response to goldspotted oak borer, Agrilus

auroguttatus, injury in southern California. For. Ecol. Manage. 261: 1852–1865.

Coleman, T.W., Lopez, V., Rugman-Jones, P., Stouthamer, R., Seybold, S.J., Reardon, R.,

Hoddle, M., 2011b. Can the destruction of California’s oak woodlands be prevented? Potential for

biological control of the goldspotted oak borer, Agrilus auroguttatus. BioControl (DOI:

10.1007/s10526-011-9404-4).

Coleman, T.W., Graves, A.D., Hoddle, M.S., Heath, Z., Flint, M.L., Chen, Y., and Seybold, S.J. 2012. Forest

stand composition and impacts associated with Agrilus auroguttatus Schaeffer (Coleoptera:

Buprestidae) and Agrilus coxalis Waterhouse in oak woodlands. For. Ecol. Manage. (in revision,

February 18, 2012).

Coleman, T.W., Seybold, S.J., 2008. Previously unrecorded damage to oak, Quercus spp., in

southern California by the goldspotted oak borer, Agrilus coxalis Waterhouse (Coleoptera:

Buprestidae). Pan-Pac Entomol. 84: 288–300.

Coleman, T.W. and Seybold, S.J. 2008. New pest in California: The goldspotted oak borer, Agrilus

coxalis Waterhouse. USDA Forest Service, Pest Alert, R5-RP-022, October 28, 2008, 4 pp.

Coleman, T.W., Seybold, S.J., 2011. Collection history and comparison of the interactions of the

goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), with host oaks in

southern California and southeastern Arizona, U.S.A. Coleop. Bull. 65: 93–108.

Dodds, K.J., Gilmore, D.W., Seybold, S.J., 2010. Assessing the threat posed by indigenous

exotics: A case study of two North American bark beetle species.

Ann. Ent. Soc. Am. 103: 39–49.

Hishinuma, S., Coleman, T. W., Flint, M. L., and Seybold, S. J. 2011. Goldspotted oak borer: Field

identification guide, University of California Agriculture and Natural Resources, Statewide

Integrated Pest Management Program, 6 pp., January 13, 2011,

http://www.ipm.ucdavis.edu/PDF/MISC/GSOB_field-identification-guide.pdf

http://www.ipm.ucdavis.edu/PDF/MISC/GSOB_field-identification-guide.pdf


Figure from Seybold and Coleman: Update on the status of the goldspotted oak borer in California. Two adult goldspotted oak borers, Agrilus auroguttatus, named for the six gold spots on the surface of the wing covers.


Giant sequoia seed production

K. Somers1, R. York1, T. Griffis2, M. Holton3, D. Katz3 and C. Crilley3

1 UC Center for Forestry and Department of Environmental Science, Policy, and Management, University of

California, Berkeley, CA 2 L. A. Moran Reforestation Center, CALFIRE, Davis, CA 3 Cornell Tree Climbing Institute, Cornell University, Ithaca, NY

In 2010, a long term collaborative research project between the Center for Forestry,

University of California, Berkeley, Cornell Tree Climbing Institute, Cornell University, and the

L.A. Moran Reforestation Center, CAL FIRE was initiated at Whitaker’s Forest Research Station.

Our first year goal was to determine the relationship between distinct cone characteristics of giant

sequoia (Sequoiadendron giganteum) and the seed viability within. Despite many decades of seed

collection experience and some related literature, the understanding of cone maturity and seed

production was very limited. In the first week in June 2010, we used the following methods to

identify cone maturity characteristics:

• Mature trees were climbed using ascenders (spur-less climbing), and cone were lowered to

the ground in bags.

• All various conditions of cones were destructively sampled to determine seed maturity and

quantity.

• Five to nine bushels of “target” cones from three study trees were collected and then

processed at the L.A. Moran Reforestation Center.

Study trees #158 and #159 (Whitaker’s tree tag identification system) were combined into one lot

for processing. The target cones had brown stems (peduncles), and the outer cone was green with

yellow and or brown mottling (2nd year cones). Eleven bushels produced 8.86 pounds

(0.79lbs./bu.) of viable seed with a germination of 66%. Study tree #213 was primarily 1st year

cones, green stem and outer cone. Nine bushels yielded 6.5 pounds (0.72 lbs./bu.) of viable seed

with a germination of 58%. The targeted cone collection more than doubled seed yield over

typical collections (0.33lbs./bu.) done in the past by other individuals or agencies (Figure 1).

In 2011, in addition to 1st and 2nd year cones, 3rd year (brown stem brown cone) and 4th

year and older cones (weathered brown to grey) were collected to determine yield of older age

classes. Samples were collected from four randomly selected mature giant sequoias using the

same methods as in 2010 and combined by age class into four lots for processing at L.A. Moran.

Yield by age class was: 1st year 0.80 lbs./bu., 2nd year 0.94 lbs./bu., 3rd year 0.05 lbs./bu., >4


years less than 500 seeds/bu. (Figure 2). Giant sequoia seed ranges from 75,000 to 110,000

seeds/pound.

Conclusions and Implications

• For the trees that we sampled, giant sequoia cones released most their seed in the fall after

maturing for two years. Seed yield was high following 1 full year of cone development

and culminated after 2 years, but dropped dramatically after 3 years.

• After one full year of development, cones contain viable seed. These 1 year old cones will

open if the branch they are attached to breaks or if they are exposed to heat from a high

intensity fire. Counter to common assumptions, our results indicate that large giant

sequoia do not store seeds for long periods of time but instead rely upon consistent seed

production followed by a 2-year seed storage period in order to colonize areas following

fire.

• Collections of opportunity (ground collection of cones detached from the tree during storm

events) are best timed in the spring and should target 1 or 2 year old cones (i.e. green

cones and green stems, or green cones with brown stems). Cones open after exposure to

heat from the sun.

Figure 1 from Somers, York, Griffis, Holton, Katz, and Crilley: Giant sequoia seed production.

Targeted 2010 Collection vs. Typical

0

0.2

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0.8

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1 2

Cone Age in Years

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ds

/ B

us

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Figure 1 from Somers, York, Griffis, Holton, Katz, and Crilley: Giant sequoia seed production.

2011 Collection

Yield of Viable Seed By Cone Age

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Prescribed fire and mechanical thinning effects on subsequent bark beetle caused tree mortality in a mid-elevation Sierran mixed-conifer

forest

Daniel T. Stark1, David L. Wood1, Andrew J. Storer2, Scott L. Stephens1

1 Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 2 School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI

We assessed bark beetle (Coleoptera: Curculionidae, Scolytinae)-caused tree mortality in a

mixed-conifer forest at Blodgett Forest Research Station (BFRS) in the central Sierra Nevada

following four treatments: 1) no treatment (CONTROL), 2) prescribed fire (FIRE ONLY), 3)

mechanical (crown thinning-from-below followed by rotary mastication) (MECH), and 4)

mechanical followed by prescribed fire treatments (MECH+FIRE), as part of the National Fire

and Fire-Surrogate Study (FFS). Ponderosa pine (Pinus ponderosa Laws) mortality caused by the

western pine beetle (Dendroctonus brevicomis LeConte), sugar pine (Pinus lambertiana Dougl.)

mortality caused by mountain pine beetle (D. ponderosae Hopkins), and white fir (Abies concolor

[Gord. And Glend.] Lindl.) mortality caused by the fir engraver beetle (Scolytus ventralis

LeConte) was assessed pre-treatment (PRE), one-year post treatment (POST1), and three years

post treatment (POST2). Bark beetle-caused mortality (%) was calculated among treatments

within sampling years and between sampling years. For the duration of the study, bark beetle-

caused mortality across all treatments for each tree species was less than 7%. In the pre-treatment

forest, mortality was uniformly low (less than 1%) or zero across all tree species and size

categories with no significant differences among future treatment units. Bark beetle-caused

mortality of small and medium white firs increased in treatments that included fire, and bark

beetle-caused mortality of sugar pines was elevated in the fire only treatment compared with other

treatments. Since trees damaged or weakened by fire are susceptible to attack by bark beetles,

second order fire effects (i.e. indirect mortality) should be taken into consideration in any

prescribed fire management plan. Likewise, the potential for increased levels of bark beetle

attacks resulting from mechanical treatments should also be considered. Our results indicate that

for the short term (3 years post-treatment), mechanical treatments appear to result in lower risk of

tree mortality compared with the bark beetle and fire-caused mortality in treatments involving

prescribed fire. In addition, the higher secondary mortality in the small and medium white firs in

both fire treatments can be considered a benefit in second-growth ponderosa pine forests where

the understory is dominated by shade-tolerant white firs.


Invasion dynamics of Scotch and Spanish broom at the range margin

Jens Stevens and Andrew Latimer

Department of Plant Sciences, University of California, Davis, CA

There is concern that climate change may lead to invasive species expanding their range to

higher elevations in mountain ranges. In temperate montane forests such as those California’s

Sierra Nevada, changes in snowpack may influence population dynamics of invasive plants by

altering the length of the growing season. Changing climate in these forests will likely interact

with forest management approaches designed to reduce wildfire risk and restore forest health by

thinning stands to remove fuels. Uncertainties, and lack of empirical data, regarding these

interactions makes forecasting invasive species spread difficult, despite increasing interest in this

problem. Here I present the early stages of an experiment to study the interacting effects of

snowpack, fire and forest structure on two invasive shrubs from the foothills of California’s Sierra

Nevada: Scotch broom (Cytisus scoparius L. Link) and Spanish broom (Spartium junceum L.).

I am utilizing a forest system at Blodgett Research Forest that is either at (Scotch broom)

or beyond (Spanish broom) the current elevation range limit of these invaders. In October 2011, I

sowed seeds from each species into a set of 14 blocks arranged across a gradient of forest canopy

cover, ranging from dense forest to small clearcuts. A subset of 4 blocks were burned shortly after

planting. Within each block, I established three sets of three plots containing either Scotch broom,

Spanish broom, or neither species. Each set of plots will receive a snowpack manipulation

treatment that either increases, decreases, or does not change ambient snowpack. This experiment

will run through three winters, during which I will measure plant germination and growth rates,

changes in soil nitrogen and soil moisture, and tree seedling survival, in response to snowpack

treatments, fire, and forest canopy conditions. Data will enable me to construct population models

for each species under a range of future conditions, and thus to better understand the constraints

on range expansion of these two invaders in forests of the Sierra Nevada.


Aging of large giant sequoia

Ariel Thomson and Robert A. York

UC Center for Forestry and Department of Environmental Science, Policy, and Management, University of


They are loved for their beauty and majestic nature and admired for their great size and

longevity; however, giant sequoias (Sequoiadendron giganteum) are still a mystery in many ways.

We know that they are old - we say they have been around for centuries, even millennia. But

confident estimates of age remain elusive because of sampling difficulties. We attempted to find

more confident figures in seven groves across Giant Sequoia National Monument and near

Whitaker’s Forest Research Station by collecting core samples and refining existing age

extrapolation equations.

This study was done as component of another project looking at the degree to whic large,

old giant sequoia respond to a gradient of disturbance severity. All study trees for the release

study were aged. The study area consisted of 7 groves within Giant Sequoia National Monument

in two ranger districts, Hume Lake and Western Divide. Study trees selected from each grove had

various measurements taken including diameter, bark thickness, and height to core. Each tree was

cored one or two times with a 24” increment bore at as close to breast height as possible.

Cores were allowed to dry, mounted, and sanded. Using the core data and tree data we

estimated ages from 41 cores. Results showed the age range to be extremely wide- from 271 to

2458 years. In general, ages tended to vary less within grove that over the entire study area.

Confidence intervals will be applied to these figures according to previous estimates that have

validated the extrapolation equations. These ranges in age will go on to be used in the overall

study to say with some degree of certainty the age at which giant sequoia are still releasing.

These age estimates also gave insight into the visible appearance of sequoia relative to

age. We found that while there may be physical differences between the very oldest and very

youngest sequoias (i.e. a thousand years difference) in general it is very difficult to use physical

appearance or tree size as an indicator of age.


The figures generated from this study are still only rough estimates, which will always be

limited by sampling difficulty in these very large trees. But given a 2000 year old tree, an age

estimate that is 2 centuries off is still within 10% and can be critical information for further

research and management related to giant sequoia that incorporate the time scales over which they

persist.


Stabilization of diverse microbial residues in California and Puerto Rico forest soils

Heather Throckmortona, Jeffrey Birdb, Laura Danec, Mary Firestonec, and William R. Horwatha

a Department of Land, Air, and Water Resources, University of California, Davis, CA b Department of Ecology, Evolutionary Biology, and Behavior, Queens College, CUNY, Flushing, NY c Department of Environnmental Science, Policy, and Management ,University of California, Berkeley, CA

The contribution of C from the turnover of diverse microorganisms to stable C pools

remains poorly understood. This study follows the turnover of 13

C labeled nonliving residues from

diverse microbial groups in situ in a temperate forest (Blodgett Forest) California (CA) and a

tropical forest (Luquillo Forest) Puerto Rico (PR), during 5 sampling points per site- over a 3 and

2 year period, respectively. Microbial groups include fungi, actinomycetes, Gm(+) bacteria, and

Gm(-) bacteria, isolated from CA and PR soils to obtain temperate and tropical isolates. Results

indicated that, despite unique biochemical makeup among groups as determined by Py-GC-MS,

microbial residues exhibited similar mean residence times (MRTs) within each site. A density

fractionation approach isolated: a “light fraction” (LF), non-mineral aggregate “occluded

fraction” (OF), and a “mineral bound fraction” (MF). Microbial C inputs were more stable in the

OF and MF than the LF throughout the course of the study at both sites. There were no significant

differences in 13

C recovery among microbes in any PR fractions, despite minor differences in

overall MRTs. In CA, there were some significant differences in 13

C recovery among microbial

inputs in the LF and OF, which related to 13

C recoveries in whole soils. In the CA MF, microbial

recoveries did not differ, and low variability among treatments was observed. Results support

increased protection of microbial C via association with the mineral matrix; however, differential

sorption of some microbial isolates over others was not observed. Overall results suggest that

inherent recalcitrance of microbial residues may be more important to determining its stability in

CA soils when it is 1) unassociated with the mineral matrix (LF); or 2) occluded within

aggregates; compared with that strongly associated with mineral surfaces (MF). The overall

composition of SOM in fractions also differed, with a greater concentration of benzene and N

compounds in the MF; lignin and phenol compounds in the LF; and aliphatics in the OF. Such

differences among fractions in OM chemistry suggest unique stabilization mechanisms for the

distinct SOM pools. SOM chemistry was most similar in the LF across sites, compared with the

OF and MF, suggesting that differences in SOM chemistry between sites may be more attributed


to differential decomposition processes rather than unique litter quality inputs. Compound-

specific turnover for temperate fungal isolates suggested conservation and transformation of

compounds from input residues. A greater 13C enrichment of N-compounds and polysaccharides

in soils relative to other compounds indicated that the composition of original inputs continued to

influence the chemistry of residual and/or decomposition products, even after 2 and 3 years in CA

and PR, respectively. Evidence for transformation of input compounds was observed in the form

of 13C enrichment of novel compounds in soils (that were not present in original residues).

Further, several compounds exhibited little change to an increase in 13C/12C over time in soils,

serving as further evidence for differential stability of unique compounds at the molecular level.


Application of scanning calorimetry to estimate soil organic matter loss after fires

Sergey V. Ushakov, Divya Nag, Alexandra Navrotsky

Peter A. Rock Thermochemistry Laboratory NEAT ORU, University of California, Davis, CA

The severe heating of soil during wildfires and prescribed burns may result in

adverse effects on soil fertility due to organic matter loss. No rapid and reliable procedure

exists to evaluate soil organic matter (SOM) losses due to heating. Enthalpy of SOM

combustion correlates with organic matter content. Quartz is a ubiquitous mineral in soils

and has a remarkably constant composition and reversible α→β phase transition at 575 °C.

We suggest that SOM content in heated and unheated soils can be compared using the ratio

of SOM combustion enthalpy on heating to the b–a quartz transition enthalpy measured on

cooling of the same sample. This eliminates the need to dry and weigh the samples, making

possible field applications of the proposed method. The feasibility of using the (ΔHcomb

SOM)/(ΔHα β Qz) ratio was established with experiments on soil samples heated in the

laboratory and the method was then used for evaluation of SOM loss on two pile burn sites

at University of California, Berkeley’s Blodgett Forest Research Station in Georgetown,

California.


-2

-1

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Burned 0-2.5

2.5-5

100 200 300 400 500 600

exo

exo

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500 600

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SOM lossH O loss2

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Figure 1 from Ushakov, Nag, Navrotsky: Application of scanning calorimetry to estimate soil organic matter loss after fires. Differential scanning calorimetry traces of Holland-Musick soil type samples on heating in air at 20 °C/min. Traces for β-α quartz phase transition on cooling are shown on the inset. Control soil sample collected outside of pile burn is selected by a thicker trace

Table 1 from Ushakov, Nag, Navrotsky: Application of scanning calorimetry to estimate soil organic matter loss after fires. Thermal analysis of samples from two pile burns site in Blodgett Forest Research Station

A test of the application of the ∆Hc/∆Hqz ratio for estimation of SOM loss was

performed on samples collected from the pile burns. No sieving or drying was performed

before the analysis and soil samples were loaded field moist after removal visible leaves

and roots and stones. The resulting DSC traces for Holland-Musick samples are plotted in

Fig. 1 and SOM losses calculated from ∆Hc/∆Hqz ratios are presented in Table 1.

Soil type, depth/cm -∆Hc/mJ Tc/°C -∆Hqz/mJ ∆Hc/ ∆Hqz SOM

loss/wt%

Unburned 0-2.5 47094 299 128.8 366 0 Holland Burned 0-2.5 814 - 195.3 4.2 98.9

2.5-5 879 - 232.5 3.8 99 Unburned 0-2.5 44900 287 74.94 599 0

Holland- Burned 0-2.5 9.173 414 171.5 0.1 100 Musick 2.5-5 564.1 408 85.76 6.6 98.9

5-7.5 16822 367 79.18 212 64.6 7.5-10 55799 289 117 477 20.4


Endothermic peaks at 25-200 °C related to water loss are observed for all samples. It is not

surprising since both sites were exposed to rain and then buried under snow for four months

after burning. An unburned sample indicates higher water content than burned samples

above 5 cm depth (Fig. 1). This correlates with organic matter loss in the burned samples

since SOM is the most hygroscopic constituent in the soil.

From the ∆Hc/∆Hqz ratio, more than 90 wt % of SOM was lost in the first 5 cm of

soil at both sites. Substantial loss of organic matter is evident for the Holland-Musick

sample at 5-7.5 cm depth. For the sample from 7.5-10 cm depth, the ∆Hc/∆Hqz ratio is only

20% lower than for the unburned control sample from 0-2.5 cm depth. This variation may

be due to decrease in SOM content with depth. Total organic matter loss on heating is a

function of heat input, exposure time, moisture content and aeration. ∆Hc/∆Hqz can only be

used as an integral indicator and cannot distinguish among these factors. It is likely that

changes in combustion onset and enthalpy per gram of organic matter can provide

possibilities to reconstruct time-temperature profiles during fires, but this will require site-

specific calibrations.

Published in: Journal of Thermal Analysis and Calorimetry (2011) 104:351–356


Eddy fluxes of nuclei mode particles to pine forest during BEARPEX’09

Richard J. Vong1, Ivar J. Vong1, David S. Covert2

1College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 2Joint Institute for the Study of Atmospheres and Oceans, University of Washington, Seattle, WA

BEARPEX'09 was conducted for seven weeks during June and July 2009 at a forested site

located near Blodgett Forest, California. Simultaneous and continuous data were collected at 2 Hz

by a particle counter (wCPC: TSI) that sensed the sum of all particles (0.010 µm ≤ Dp) and a

sonic anemometer (ATI) for the determination of particle ‘eddy correlation’ fluxes. We also

operated an electrical mobility (TSI DMA) instrument for determining the aerosol size spectra at

10 minute intervals.

The site was hot and dry for both BEARPEX field experiments but winds (U*) and aerosol

concentrations changed somewhat between the 2007 and 2009 experiments. There were lower

wind speeds and U*, and lower concentrations of accumulation mode particles in June-July 2009

compared to Sept. 2007.

We anticipated that there would be issues associated with particle hygroscopic growth and

counting particles but these factors were not important for wCPC eddy fluxes. Hygroscopic

growth was not an issue because here were very few particles near the minimum diameter sensed

by the wCPC based on size spectra collected by the DMA. The wCPC cospectra were similar to

those for heat and vapor (Fig.1) suggesting that most of the nuclei mode particle flux was

captured by this 2 Hz sampling rate.


Figure 1 from Vong, Vong, and Covert: Eddy fluxes of nuclei mode particles to pine forest during BEARPEX’09. Co-spectra for particles (from the wCPC), heat, and momentum during BEARPEX’09

However, the wCPC would be sensitive to ultrafine particles from gas-to-particle

conversion of biogenic emissions from the pine forest and from a nearby generator. Northerly

winds that occurred primarily at night sometimes brought generator emissions to the wCPC

during night time hours and resulted in short term concentration peaks (See Fig.2).


Figure 2 from Vong, Vong, and Covert: Eddy fluxes of nuclei mode particles to pine forest during BEARPEX’09. 30 min. time series of wind speed, direction, vertical velocity, and wCPC aerosol

concentration (peaks occur during calm northerly winds at ~1100 sec mark on the X axis).

Since this type of advection and non-stationarity violate the assumptions for eddy

correlation (producing a likely change in flux with height), we developed screening criteria to

identify these wCPC peaks by calculating variability on several scales (τ > 100 sec, < 100 sec, and

scales < 10 sec) and screening samples with unusually high values for within 30 min. variability.

After such screening we had 1246 total 30-minute eddy flux observations at varying times of day

for analysis of particle deposition.

These wCPC eddy flux results for BEARPEX 2009 are presented in Figure 3. The

observed wCPC fluxes were consistently downwards during the daytime (very little screening was

done for daytime) and also at night (after screening for peaks related to the generator). Deposition

velocites for these ultrafine particles reached 0.2 to 0.3 cm/sec for unstable conditions and during

the early afternoon.


Figure 3 from Vong, Vong, and Covert: Eddy fluxes of nuclei mode particles to pine forest during BEARPEX’09. Ultrafine particle deposition velocities from the wCPC plotted vs. U* for daytime and nighttime, according to hour of the day, and versus stability (as z/L)

DMA size distributions presented in Fig. 4 show that primarily ultrafine particles (0.030 ≤

Dp ≤ 0.100 µm) were present during BEARPEX’09; there were very few particles between (0.010

≤ Dp ≤ 0.030 µm). If there had been recent gas to particle conversion of forest biogenic VOC

emissions, there ought to have been a considerable number of particles with diameter less than 30

nm that would have been sensed by the DMA. The typical particle size was 40 to 100 nm in the

summer of 2009. Hygroscopic growth could only be important for the wCPC if there had been

particles to grow across its lower diameter threshold of 10 nm, but there were not.


Figure 4 from Vong, Vong, and Covert: Eddy fluxes of nuclei mode particles to pine forest during BEARPEX’09. Particle size distribution from the DMA during June-July 2009

From both the lack of particles smaller than 30 nm from the DMA and the consistent

downward direction of the wCPC fluxes, we conclude that new particle production from the pine

forest was small-to-negligible in the immediate upwind fetch. This material was presented at the

2010 Fall AGU meeting in San Francisco (talk A52A-07; those slides are available at

http://people.oregonstate.edu/~vongr/ ) . The work presented at AGU and herein is being

developed into a journal article during summer 2011.

Accumulation mode aerosol fluxes (using the FAST) for BEARPEX’09 also were

collected and have been analyzed including hygroscopic growth using a number of measurements

that were taken concurrently. However, the lower (by about 2X) accumulation mode aerosol

concentrations during 2009 resulted in substantially increased counting errors for the FAST

compared to 2007 and the fluxes are both smaller and nosier than those measured by the FAST

during 2007.


Size-dependent aerosol deposition velocities during BEARPEX’07

Richard J. Vong1, Ivar J. Vong1, Dean Vickers1, David S. Covert2

1College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 2Joint Institute for the Study of Atmospheres and Oceans, University of Washington, Seattle, WA

Aerosol concentrations and 3-D winds were measured from September 9 to 25, 2007,

above a pine forest in California. The measurements were combined using the eddy covariance

(EC) technique to determine aerosol eddy fluxes as a function of particle diameter within the

accumulation mode size range (0.25 μm ≤ Dp ≤ 1 μm here). Measured heat and water vapor

fluxes were utilized to correct the aerosol eddy fluxes for aerosol hygroscopic growth. The

hygroscopic growth correction was necessary despite the low RH and relatively hygrophobic

nature of the particles. Uncertainties associated with particle counting also were evaluated from

the data. Aerosol deposition velocities (Vd = EC turbulent flux / mean particle concentration)

during daytime were shown to vary from -0.2 to -1.0 cm s-1; the magnitude of particle Vd

increases with friction velocity and particle diameter.


Origins and composition of fine atmospheric carbonaceous aerosol in the Sierra Nevada Mountains, California

David R. Worton1,2, Allen H. Goldstein1,3, Delphine K. Farmer4,5, Kenneth S. Docherty4,5,*, Jose L. Jimenez4,5, Jessica B. Gilman4,6, William C. Kuster6, Joost de Gouw4,6, Brent J. Williams7, Nathan M. Kreisberg2, Susanne V. Hering2, Graham

Bench8, Megan McKay1,**, Kasper Kristensen9, Marianne Glasius9, Jason D. Surratt10,*** and John H. Seinfeld11

1 Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 2 Aerosol Dynamics Inc., Berkeley, CA 3 Departments of Civil and Environmental Engineering, University of California, Berkeley, CA 4 Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 5 Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 6 NOAA Earth System Research Laboratory, Boulder, CO 7 Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 8 Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 9 Department of Chemistry, University of Aarhus, Aarhus C, DK-8000 Denmark 10 Department of Chemistry, California Institute of Technology, Pasadena, CA 11 Departments of Environmental Science and Engineering and Chemical Engineering, California Institute of

Technology, Pasadena, CA * now at: Alion Science and Technology, EPA Office of Research and Development, EPA Research and

Development, Research Triangle Park, NC **now at: California Air Resources Board, Sacramento, CA *** now at: Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill,

Chapel Hill, NC

In this paper we report chemically resolved measurements of organic aerosol (OA) and

related tracers during the Biosphere Effects on Aerosols and Photochemistry Experiment

(BEARPEX) at the Blodgett Forest Research Station, California from August 15th

– October 10th

2007. OA contributed the majority of the mass to the fine atmospheric particles and was

predominately oxygenated (OOA). The highest concentrations of OA were during sporadic

wildfire influence when aged plumes were impacting the site. In situ measurements of particle

phase molecular markers were dominated by secondary compounds and along with gas phase

compounds could be categorized into six factors or sources: (1) aged biomass burning emissions

and oxidized urban emissions, (2) oxidized urban emissions (3) oxidation products of

monoterpene emissions, (4) monoterpene emissions, (5) anthropogenic emissions and (6) local

methyl chavicol emissions and oxidation products. There were multiple biogenic components that

contributed to OA at this site whose contributions varied diurnally, seasonally and in response to

changing meteorological conditions, e.g., temperature and precipitation events. Concentrations of

isoprene oxidation products were larger when temperatures were higher during the first half of the

campaign (August 15th

– September 12th) due to more substantial emissions of isoprene and

enhanced photochemistry. The oxidation of methyl chavicol, an oxygentated terpene emitted by


ponderosa pine trees, contributed similarly to OA throughout the campaign. In contrast, the

abundances of monoterpene oxidation products in the particle phase were greater during the

cooler conditions in the latter half of the campaign (September 13th

– October 10th

), even though

emissions of the precursors were lower, although the mechanism is not known. OA was

correlated with the anthropogenic tracers 2-propyl nitrate and carbon monoxide (CO), consistent

with previous observations, while being comprised of mostly non-fossil carbon (>75%). The

correlation between OA and an anthropogenic tracer does not necessarily identify the source of

the carbon as being anthropogenic but instead suggests a coupling between the anthropogenic and

biogenic components in the air mass that might be related to the source of the oxidant and/or the

aerosol sulfate. Observations of organosulfates of isoprene and α-pinene provided evidence for

the likely importance of aerosol sulfate in spite of neutralized aerosol although acidic plumes

might have played a role upwind of the site. This is in contrast to laboratory studies where

strongly acidic seed aerosols were needed in order to form these compounds. These compounds

together represented only a minor fraction (< 1 %) of the total OA mass, which may be the result

of the neutralized aerosol at the site or because only a small number of organosulfates were

quantified. The low contribution of organosulfates to total OA suggests that other mechanisms,

e.g., NOx enhancement of oxidant levels, are likely responsible for the majority of the

anthropogenic enhancement of biogenic secondary organic aerosol observed at this site.


Seasonal differences in isoprene and monoterpene organosulfate concentrations above a ponderosa pine forest in California

David R. Worton1,2, Jason D. Surratt3, John H. Seinfeld4, Kasper Kristensen5, Marianne Glasius5, Jeong-Hoo Park1, Melinda Beaver6, Paul Wennberg6 and

Allen H. Goldstein1,7

1 Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 2 Aerosol Dynamics Inc., Berkeley, CA 3 Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 4 Departments of Environmental Science and Engineering and Chemical Engineering, California Institute of

Technology, Pasadena, CA 5 Department of Chemistry, University of Aarhus, Aarhus C, DK-8000 Denmark 6 Departments of Geology and Planetary Sciences and Environmental Science and Engineering, California Institute of

Technology, Pasadena, CA 7 Department of Civil and Environmental Engineering, University of California, Berkeley, CA

Organosulfates formed from biogenic hydrocarbons have been observed in both smog

chamber experiments and ambient aerosols. They represent a class of compounds that result from

the coupling of biogenic and anthropogenic emissions and serve as tracers of the anthropogenic

enhancement of biogenic secondary organic aerosol. High volume filter samples were collected

during the Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX) for two

five days periods, one in September 2007 and the other in July 2009, in the Sierra Nevada

Mountains of California. The filter samples were solvent extracted and analyzed by liquid

chromatography coupled to electrospray ionization high-resolution time-of-flight mass

spectrometry at the California Institute for Technology and the University of Aarhus, Denmark.

The two sampling periods were distinct; the 2007 sampling period was characterized by cool

temperatures and high relative humidities whereas in 2009 it was much hotter and drier. In total,

16 organosulfates were quantified, of which five were derived from isoprene including the sulfate

ester formed from the epoxy diol (IEPOX). Concentrations of the IEPOX organosulfate were

substantially higher during 2009 (factor of ~ 10) relative to 2007 and indicate that higher isoprene

emissions and enhanced photochemistry were likely important drivers controlling its abundance in

the particle phase. In contrast, the organosulfate formed from methacrolein (MACR) was below

the detection limit in 2009 while in 2007 concentrations were about 50 % of the IEPOX

organosulfates. The MACR organosulfate is thought to form via MPAN and its absence in 2009

would suggest that the MPAN thermal lifetime is too short for it to be further oxidized by OH to

produce aerosol. We compare and contrast all the organosulfate measurements and supporting


measurements of the gas phase precursors to provide insights into the formation mechanisms of

these organosulfates that are vital to facilitate inclusion in models.


The Center for Forestry website: Changes and future directions

Tong Wu

Center for Forestry, University of California, Berkeley, CA

The Center for Forestry website has undergone significant changes over the past six

months, in both visual appearance and underlying “infrastructure.” The redesign has reorganized

the original content in a way that is more accessible, in particular by introducing a new

navigational interface and an interactive “slideshow” that relays the latest publications and

updates in a user-friendly format. Additionally, the aesthetics of the pages now have a more

contemporary and refined feel. With regard to more technical alterations, the website has

transitioned to WordPress as the content management system. This framework is easier to use

and has more opportunities for future development. Planned amendments to the website include

additional enhancements to the navigation, a multimedia section to showcase images and video

from the center’s research sites, and a list/database of center-related publications. These changes

are expected to be completed over the next few months.

Figure from Wu: The Center for Forestry website: Changes and future directions


Growth response of large, old giant sequoia trees to a disturbance intensity gradient

Robert A. York1 and Scott Sink2

1UC Center for Forestry and Department of Environmental Science, Policy, and Management, University of

California, Berkeley, CA 2Department of Forestry and Natural Resources, California Polytechnic State University, San Luis Obispo, CA

In 2011, we measured the growth rate of large giant sequoia growing at sites that

experienced logging in the 1980’s. The logging represented a relatively high severity disturbance

event, where most trees except for giant sequoia were removed. We cored trees in order to

measure the growth response to the disturbance, comparing the study trees to nearby controls.

Study sites included several groves from the central portion of the range of giant sequoia,

including the Redwood Mountain grove and trees from Whitaker’s Forest. Early results suggest

that giant sequoia trees respond positively in growth to disturbance severity. That is, higher

severity disturbances result in longer periods of rapid growth. This helps us to better define the

life history of giant sequoia. It appears that giant sequoia capitalizes on a variety of disturbances

severities throughout its lifespan, not just during the regeneration phase as is often assumed. This

has implications for treatments such as prescribed fires and thinning for fire hazard reductions.

Surprisingly, large giant sequoia trees appear very plastic in their capacity to respond to changes

in their environment. Growth increases have been detected following even very low severity

disturbances such as a low severity prescribed fire. Further lab analysis will be necessary to

confirm results.


A gap-based approach for regenerating pine species and reducing surface fuels in multi-aged mixed conifer stands in the Sierra Nevada,

California

Robert A. York1,2, John J. Battles 2, Rebecca C. Wenk2, and David Saah3

1 UC Center for Forestry, University of California, Berkeley, CA 2 Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 3Spatial Informatics Group, LLC, Pleasanton, CA

Multi-aged stands in a mixed conifer forest of California (Blodgett Forest compartments

230 and 110) were treated to mitigate harvest-related increases in surface fuels and to prepare

sites for natural regeneration of Pinus species. The study was designed to: 1) assess effectiveness

of small gap fuel treatments (piling and burning in 0.04 ha gaps) on surface fuel and modeled fire

behavior; 2) test the effect of substrate quality on germination of Pinus species; 3) measure the

influence of gap creation on light availability and stand-level light heterogeneity. While the fuel

treatment only covered 10% of stand area, it was effective in avoiding increases in stand-level

surface fuel following harvests. Fire behavior was predicted to be moderate following the

treatments. The harvest coupled with the gap surface fuel treatments did not change predicted fire

behavior compared to the pre-treatment stands. There was a significant but variable increase in

germination of P. ponderosa seed when sowed on ash substrates compared to bare soil. No

substrate effect was detected for P. lambertiana. The 0.04 ha gaps created distinct pockets of light

and greatly increased stand-level light heterogeneity. This gap-based approach to regenerating

multi-aged stands coupled with small-scale fuel treatments is promising for reducing fire hazard

and regenerating shade-intolerant species.


Figure from York, Battles, Wenk, and Saah: A gap-based approach for regenerating pine species and reducing surface fuels in multi-aged mixed conifer stands in the Sierra Nevada, California. The relative distribution of the percent of total transmitted radiation above the canopy reaching the florest floor in an unharvested reserve stand and in a stand prior to and following a multiaged selective harvest at Blodgett Forest Research Station, California. Stand-level measurements are from samples distributed across the stand, regardless of proximity to canopy gaps.

Total Transmitted Radiation (%)

0-5

5-1

0

10

-15

15

-20

20

-25

25

-30

30

-35

35

-40

40

-45

45

-50

Re

lative

Dis

trib

utio

n

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Unharvested reserve

Selection stand before harvest

Selection stand after harvest


Density effects on development of young giant sequoia (sequoiadendron giganteum): Growth trends and competition

dynamics through 22 years

Robert A. York1,2, Kevin L. O’Hara2, and John J. Battles2

1 UC Center for Forestry, University of California, Berkeley, CA 2 Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA

Giant sequoia were planted at various densities and tracked for 22 years to quantify the

effect of growing space on diameter, height, branch diameter, and branch density. Stem volume

was also measured using equations developed from stem analysis of young, open-grown giant

sequoia. Beginning after just 4 years and continuing through year 22, both stem diameter and

height growth were highly sensitive to initial planting density (expressed in this case as horizontal

growing space per tree) within the tested range of 3.7 to 28.4 m2. Through 22 years, treatments

allocating the greatest growing space per tree had greater volume per tree with no tradeoff yet

observed in stand level volume growth. Branch diameter at breast height along the stem generally

increased with growing space, but branch density did not change. To meet objectives,

management strategies should be tailored to the species’ specific growth strategies. Giant sequoia

is characterized by rapid early growth coupled with exceptionally low mortality, which has

relevance in both native grove restoration as well as plantation management contexts. The

measurements in this study suggest either planting at low density or thinning giant sequoia very

early in dense stands in order to increase individual tree growth rates without a corresponding

reduction in stand volume. Young stands developing following stand replacing fires may benefit

from low-severity prescribed burns if objectives are to increase average stem growth or canopy

recruitment.


Figure from York, O’Hara, and Battles: Density effects on development of young giant sequoia (sequoiadendron giganteum): Growth trends and competition dynamics through 22 years. Effect of density on growth of planted giant sequoia through 22 years. a-c: mean dbh, height, and crown radius per treatment area against growing space (i.e. planting density); means shown are from repeated measurements following the 4th, 10th, 16th, and 22nd growing seasons; equations given are for the 22nd year curves. d-f: trends in the slope parameters from the above curves; bars are 95% confidence intervals for the parameter. The slope and confidence limits for the height curve (panel e) are calculated as the first derivative along the curve where x = 1/2 * asymptote.

Growing space per tree (m2)

444 555 666 777 111111 151515 191919 242424 282828

Mea

n d

bh (

cm)

0

10

20

30

Y=2.71+9.63*log(x)

Years after planting

4 10 16 22

Slo

pe

of

dbh

-gro

win

g s

pac

e cu

rve

0

2

4

6

8

10

Year 16

Year 10

Year 4

a.

d.


444 555 666 777 111111 151515 191919 242424 282828

Mea

n H

eig

ht

(m)

2

4

6

8

10

12

14Y=(14.74*x) / (4.02+x)


4 10 16 22

Slo

pe

of

hei

gh

t-gro

win

g s

pac

e cu

rve

0.5

0.6

0.7

0.8

0.9

Year 16

Year 10

Year 4


444 555 666 777 111111 151515 191919 242424 282828

Cro

wn r

adiu

s (m

)

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0 Year 16

Year 22

Year 4

b. c.

f.e.


4 10 16 22

Slo

pe

of

cro

wn

rad

ius-

gro

win

g s

pac

e cu

rve

0.0

0.1

0.2

0.3

0.4

0.5

Year 22Year 22Year 10

Y=0.23+0.43*log(x)


Size structure of giant sequoia at Whitaker’s Forest in the context of all southern Sierra groves

Robert A. York1,2 and John J. Battles2


Data from permanent monitoring plots at Whitaker’s Forest were used in a population-

wide assessment of giant sequoia, in coordination with the Sequoia Kings Canyon National Park

and Giant Sequoia National Monument. The effect of a mechanical restoration treatment on the

size structure of giant sequoia was measured with a departure index, which quantifies changes in

distributions. The departure index M for stem diameter size class distribution was calculated for

the 2009 survey and then compared against M for the 1999 distribution. The effect of the

treatment on size structure was evaluated by using a Wilcoxon rank sum test (one-way) to

evaluate if the treatment was effective at shifting the distribution further to the left (i.e. increasing

the relative number of small trees). The results indicated that the 1999 distribution was already

heavily left shifted to begin with (this is apparent from the gray bar distribution from Whitaker’s

in the figure below), which made it more difficult to detect a shift further to the left with a

statistical test. Despite this, the departure in M was sufficiently large (-0.10) to detect a shift at p =

0.07. The leftward shift to more small trees represented a shift that was 45% of the maximum

possible (i.e. 100% of trees within the smallest size class). The results demonstrate that this

approach has good potential for use in evaluating future trends in giant sequoia structure,

especially following treatments in areas where current structures are considered undesirable (e.g.

the 1999 Whitaker’s structure).


Tre

es /

ha

0

5

10

15

20

0

2

4

6

8

10

15-cm diameter class

15 45 75 105 135 165 195 225 255 285

Tre

es /

ha

0

2

4

6

8

10

12

14

15-cm diameter class

15 45 75 105 135 165 195 225 255 285

0

5

10

15

20

25

30

35

40

45

50

1999,

2009,

n = 419

n = 429

300+ 300+

1.7 tph

3.1 tph1.3 tph

1.8 tph

SEKI ~ 1970

35 groves

N = 163,231

GSNM ~ 2006

24 groves

n = 508

CDF- Mt. Home ~ 2005

n = 2007UCB - Whitaker's (Redwood Mt. Grove)

23 -

Figure from York and Battles: Size structure of giant sequoia at Whitaker’s Forest in the context of all southern Sierra groves. Size structure of giant sequoia by agency in the southern Sierra Nevada. The Y-axis is different between each graph because the size structures are meant to show only general differences between agencies. Also note that the gaps between larger size classes in the SEKI data are because diameters were measured to resolutions greater than the 15-cm bin widths.


Stem breakage probability in mature mixed conifer plantations

Robert A. York1,2 and Rose DeVries2


In 2010 and 2011, we measured trees that had snapped from recent snow and wind storms in

mature (25-30 years) plantations at Blodgett Forest. Snapped trees were measured for height and

diameter. Reference trees were also measured to see if they were any different than snapped trees.

Preliminary results suggest that snapping probability is highly dependent upon species, where

ponderosa pine snapped with much higher frequency than giant sequoia, which very rarely

snapped. Douglas-fir was in between ponderosa pine and giant sequoia. The dominant tree

morphological factor appeared to be height to diameter ratio, with greater ratios resulting in

higher snapping probabilities. Local stem density could not be detected as a contributor to

snapping probability. These results have potential implications for young plantation management

as well as species selection for plantations.

Proceedings of the 2012 BFRS Workshop

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