Post on 13-Sep-2020
Patterns of Spruce Regeneration in the
Gunnison National Forest
Mike Battaglia, USFS RMRS Jason Sibold, CSU Tony Cheng, CSU/CFRI
Goals• Fill in critical
knowledge gaps:
• assist management/decrease uncertainty
• provide information for adaptive management
Specific Goals• Establish monitoring baselines to
understand ecological results of treatments
• Patterns of spruce regeneration in relation to:
• landscape position
• treatment location and implementation
• past treatments
• treatment locations, can treatments in green stands initiate a pulse of regeneration?
• microsite conditions
• post-treatment conditions
4
Current Research Topics
• Comparison of previously harvested stands and unharvested stands • Tree Mortality • Post-beetle stand structure • Tree regeneration
Previously Harvested Sites – plots installed 2015
Site Forest type Control PRE-TRT 2015
Salvaged
LaGarita Spruce 4 4 4 (Cut 2015)
Rambouillet
Spruce need 12 5 (Cut 2015)Spruce-fir need 1
Spruce-Aspen need 1
Roadside Spruce 3 3 3 (Cut 2015)West Pinos Spruce 3 3 (cut 2014)
Windy Point Spruce 5 5 (cut 14/15)
Unharvested Sites – plots installed 2015
Forest type Control
Spruce 41
Spruce-Aspen 7
Plot set-up and MeasurementsFull plot size: 0.05 Hectare (0.12 acres)
Tallied all seedlings
Tallied all seedlings
Coarse Wood Transects and Forest Floor depth
Trees > dbh On entire plot • Species • Diameter • Status (live/
dead) • Agent of death • Cone presence • Subset of ages
Seedlings (< dbh) On NE and SW quadrat of plot • Species • Height class • Age category (<5 yrs or >5 yrs) • Damage
Substrate subplot• Litter • Rock • Woody
material • Soil • Moss • Stump • Vegetation
Microsite for seedling establishment 15 Spruce seedlings per quadrat Same categories as substrate subplots Distance and identification of ‘nurse’ objects
7
Tree mortality in Spruce stands high
Spruce Beetle OutbreakBefore After
Tota
l Tre
es p
er a
cre
0
200
400
600
800
1000Unharvested Previous Harvest Salvage
• Pre-outbreak: Previously harvested stands were denser (Basal area and TPA) than unharvested stands
• Post-outbreak: 94-95% total BA mortality but only ~65% TPA mortality
• Post-outbreak: There was no difference in Total Basal Area
• Post-outbreak: Previously harvested stands had more TPA than salvaged areas, but similar TPA to unharvested stands. Unharvested stands slightly higher TPA to salvaged stands (p=0.06)
*
AB B
A
Spruce Beetle OutbreakBefore After
Tota
l Bas
al A
rea
(ft2 /a
c)
0
50
100
150
200
250Unharvested Previous Harvest Salvage
ns
*
94-95% mortality
65% mortality
Spruce stand diameter substantially reduced
Spruce Beetle OutbreakBefore After
Spru
ce Q
uadr
atic
mea
n di
amet
er (i
nche
s)
0
2
4
6
8
10Unharvested Previous Harvest Salvage
ns
ns
• Past management didn’t impact spruce diameter
• Post-outbreak spruce diameter similar across treatments
• Average spruce diameter: 1.7 inches
Diameter distribution change: Unharvested stands
Diameter distribution change: Previously harvested stands
Post-outbreak seedling density (less than DBH)
Spruce Beetle OutbreakSpruce Fir Aspen
Tree
s pe
r ac
re
0
500
1000
1500
2000
2500Unharvested Previous Harvest Salvage
AB
A
B
p=0.07
ns
• Past management didn’t negatively impact spruce seedling density
• More fir in previously harvested stands
• Spruce seedling densities exceed minimum stocking requirements
Seedling height class (inches)
U_4 to
8
H_4 to
8
U_8 to
20
H_ 8 to
20
U_20 t
o 54
H_20 t
o 54
Age
(Yea
rs)
0153045607590
105120135150165180195210225
Height Class (in)
Unharvested Median Age (Q1 and Q3)
Harvested Median Age (Q1 and Q3)
P-value
4 to 8 18 (14, 20.5)
17 (15,25)
NS
8 to 20 22 (18, 29)
33 (25, 48)
0.001
20 to 54
60 (40, 68)
70 (51, 103)
NS
It takes a long time for a spruce seedling to reach DBH
• Spruce seedlings between 8 and 20 inches tall are about 10 years younger in unharvested stands
Forest type conversion
Unharvested
Forest type
Spruce
Spruce
/fir
Spruce
/aspen
Spruce
/fir/A
spen Fir
Bristle
cone
Aspen
Nu
mb
er o
f p
lots
0
10
20
30
40
50Pre-outbreak Post-outbreak
Harvested
Forest type
Spruce
Spruce
/fir
Spruce
/aspen
Spruce
/fir/A
spen Fir
Bristle
cone
Aspen
Num
ber
of p
lots
0
10
20
30
40
50
Pre-outbreak Post_outbreak
Objectives• Are spruce
seedlings found in specific locations on the landscape?
• Is the spruce beetle outbreak creating opportunities for regeneration?
Methods
Field Sampling Sites (74)
Are older spruce (5 years old) seedlings in specific locations?
0.0 0.5 1.0 1.5 2.0
−0.5
0.0
0.5
trans_asp (22%)
fitte
d fu
nctio
n
0.0 0.2 0.4 0.6 0.8 1.0
−0.5
0.0
0.5
twi_norm (19.2%)fit
ted
func
tion
20 40 60 80
−0.5
0.0
0.5
LITTER (19%)
fitte
d fu
nctio
n
N Y
−0.5
0.0
0.5
PAST_TRT (9.4%)
fitte
d fu
nctio
n
0 10 20 30 40
−0.5
0.0
0.5
MOSS.LICHEN (7.5%)
fitte
d fu
nctio
n
2.4 2.8 3.2 3.6
−0.5
0.0
0.5
available.water.storage.0.25.cm.weight.avg (6.5%)
fitte
d fu
nctio
n
100 200 300 400 500
−0.5
0.0
0.5
age_no (5.3%)fit
ted
func
tion
3100 3300 3500
−0.5
0.0
0.5
ELEVATION (3.3%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.5
0.0
0.5
herb_shrub_cover (3.2%)
fitte
d fu
nctio
n
N Y
−0.5
0.0
0.5
potr_PA (2.8%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.5
0.0
0.5
percLDu2.5cm (1.9%)
fitte
d fu
nctio
n
Are older spruce (>5 years old) seedlings in specific locations?
0.0 0.5 1.0 1.5 2.0
−0.5
0.0
0.5
trans_asp (22%)
fitte
d fu
nctio
n
0.0 0.2 0.4 0.6 0.8 1.0
−0.5
0.0
0.5
twi_norm (19.2%)
fitte
d fu
nctio
n
20 40 60 80
−0.5
0.0
0.5
LITTER (19%)
fitte
d fu
nctio
n
N Y
−0.5
0.0
0.5
PAST_TRT (9.4%)
fitte
d fu
nctio
n
0 10 20 30 40
−0.5
0.0
0.5
MOSS.LICHEN (7.5%)
fitte
d fu
nctio
n
2.4 2.8 3.2 3.6
−0.5
0.0
0.5
available.water.storage.0.25.cm.weight.avg (6.5%)
fitte
d fu
nctio
n
100 200 300 400 500
−0.5
0.0
0.5
age_no (5.3%)
fitte
d fu
nctio
n
3100 3300 3500
−0.5
0.0
0.5
ELEVATION (3.3%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.5
0.0
0.5
herb_shrub_cover (3.2%)
fitte
d fu
nctio
n
N Y
−0.5
0.0
0.5
potr_PA (2.8%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.5
0.0
0.5
percLDu2.5cm (1.9%)
fitte
d fu
nctio
n
• 33% of distribution from BRT
• Moisture availability (north slopes, concave areas, higher elevations)
• Moisture retention (littler, moss)
• Past treatments
Are young spruce (<5 years) seedlings in specific locations?
7400 7800
−0.6
−0.2
0.2
0.6
solar_sum (30.4%)
fitte
d fu
nctio
n
2.4 2.8 3.2 3.6
−0.6
−0.2
0.2
0.6
available.water.storage.0.25.cm.weight.avg (17.7%)fit
ted
func
tion
20 40 60 80 100
−0.6
−0.2
0.2
0.6
sb_mort_stem_hi (15.3%)
fitte
d fu
nctio
n
0 10 20 30 40
−0.6
−0.2
0.2
0.6
MOSS.LICHEN (7.8%)
fitte
d fu
nctio
n
100 200 300 400 500
−0.6
−0.2
0.2
0.6
age_no (6.8%)
fitte
d fu
nctio
n
10 30 50 70
−0.6
−0.2
0.2
0.6
day (6.2%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.6
−0.2
0.2
0.6
percLDu2.5cm (5%)fit
ted
func
tion
0 20 40 60 80
−0.6
−0.2
0.2
0.6
herb_shrub_cover (4.4%)
fitte
d fu
nctio
n
20 40 60 80
−0.6
−0.2
0.2
0.6
LITTER (3.8%)
fitte
d fu
nctio
n
3100 3300 3500
−0.6
−0.2
0.2
0.6
ELEVATION (2.6%)
fitte
d fu
nctio
n
Are young spruce (<5 years) seedlings in specific locations?
7400 7800
−0.6
−0.2
0.2
0.6
solar_sum (30.4%)
fitte
d fu
nctio
n
2.4 2.8 3.2 3.6
−0.6
−0.2
0.2
0.6
available.water.storage.0.25.cm.weight.avg (17.7%)
fitte
d fu
nctio
n
20 40 60 80 100
−0.6
−0.2
0.2
0.6
sb_mort_stem_hi (15.3%)
fitte
d fu
nctio
n
0 10 20 30 40
−0.6
−0.2
0.2
0.6
MOSS.LICHEN (7.8%)fit
ted
func
tion
100 200 300 400 500
−0.6
−0.2
0.2
0.6
age_no (6.8%)
fitte
d fu
nctio
n
10 30 50 70
−0.6
−0.2
0.2
0.6
day (6.2%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.6
−0.2
0.2
0.6
percLDu2.5cm (5%)
fitte
d fu
nctio
n
0 20 40 60 80
−0.6
−0.2
0.2
0.6
herb_shrub_cover (4.4%)
fitte
d fu
nctio
n
20 40 60 80
−0.6
−0.2
0.2
0.6
LITTER (3.8%)
fitte
d fu
nctio
n
3100 3300 3500
−0.6
−0.2
0.2
0.6
ELEVATION (2.6%)
fitte
d fu
nctio
n
• 36% of variation from BRT
• Moisture availability (north slopes, higher elevations)
• Spruce beetle mortality
• Moisture retention (littler, moss)
• Negative with shrub cover
Take Homes• Are spruce seedlings
found in specific locations on the landscape? YES
• wetter topographic positions
• moisture retaining features (litter, moss)
• Is the spruce beetle outbreak creating opportunities for regeneration? YES
Caution and Next Steps• Bumper crop of spruce seedlings
in 2016!
• will they survive?
• Need a few more sites in specific topographic settings and forest types (spruce-aspen mix)
• are treatments an opportunity to shift species mix?
• Relating patterns to climate change projections
Summer 2016
• Revisit Summer 2015 plots • Seedling survival • Remeasure newly salvaged areas • Set up seed traps
• Install additional monitoring plots in Spruce-Aspen