Plant Roots and Marsh Elevation

Linda Blum 1University of Virginia

Comparison of Annual Gross Primary Production Among Major Ecosystems (103 kcal m-2 yr-1) (after Odum 1969)

Marine Terrestrial

Open Ocean 1.0 Deserts and tundras 0.2

Coastal Zones 2.0 Grasslands and pastures 2.5

Upwelling Zones 6.0 Dry forests 2.5

Marshes and Reefs 20.0 Boreal coniferous forests 3.0

Cultivated lands no energy subsidy 3.0

Moist temperate forests 8.0

Fuel subsidized ag 12.0

Wet tropical and subtropical forests 20.0

Figure courtesy Don Cahoon

Turner, et al. 2000

Nyman et al . 2006

Salt Marsh Plant Location Productivity

(g m-2yr-1) Source

D. spicata New Jersey Delaware

2780 3400

Good & Frasco (1979) Gallagher & Plumley (1979)

S. patens

New Jersey Delaware Delaware Maryland Virginia

3270 3300 470 4119 267

Good & Frasco (1979) Roman & Diaber (1984)

Gallagher & Plumley (1979) Saunders et al. (2006) Long and Blum (2010)

S. alterniflora

New Jersey Delaware Delaware Virginia Virginia Virginia

North Carolina North Carolina

2400 5000

6838-11306 5213

767-2269 744 560 460

Good & Frasco (1979) Roman & Diaber (1984)

Gross et al. (1991) Gross et al. (1991)

Blum (1993) Long and Blum (2010) Smith & Odum (1981)

Stroud (1976)

Area Height form Above Below R:S

Nova Scotia NR 803 1051 1.3

Massachusetts NR 420 3500 8.3

New Jersey Short 500 2300 4.6

North Carolina short 650 460 0.7

tall 1300 500 0.4

South Carolina Short 1272 5445 4.3

Medium 775 - -

Tall 2460 2363 1.0

Georgia Short 1350 2020 1.5

medium 2840 4780 1.7

tall 3700 2110 0.6

Root to Shoot Ratios (biomass g m2)

20 30 40 50 0

400

800

1200

1600

2000

Elevation, cm NAVD

AG b

iom

ass

(g m

-2)

-10 0 10

500

1500

2500

3500

4500

BG

ingr

owth

(g m

-3)

30 40 50 0

400

800

1200

1600

2000

Elevation, cm NAVD

AG b

iom

ass

(g m

-2)

-10 0 10 20

500

1500

2500

3500

4500

BG

ingr

owth

(g m

-3)

Biomass Root ingrowth

Biomass Root ingrowth

a) b)

Russell, E. et al. 2012

Matt Kirwan 2011

Mudd et al. 2009

Dame, R. and Paul, D. 1986 – South Carolina S. alterniflora

Blum 1993 – Virginia S. alterniflora

Seasonality of Root Biomass

Robertson, C.L. 2007.

Valiela et al. 1984

Nutrient Effects on R:S

Approaches for measuring plant roots

• Biomass – Core and sort – Core and sieve – Root in-growth cores/bags

• Productivity – Core and sort over time – Core and sieve over time

Subsiding Healthy

Live Roots

Turner et al 2004

Aboveground

Role of roots in marsh collapse

Limitations • Tedious • Labor intensive • Subjective • Indirect • Many assumptions

Photo source: http://zottoli.wordpress.com/saltmarshes/salt-marsh-pannes-and-pools/

• 1999 First use in ecological studies. Ecol. Appl. 9(3):1050-1058.

• 2012. First use to examine marsh roots. Ecol. Appl. 21(6):2156-2171

• Based on differential attenuation of X-rays

Overview of Procedure Collect and

prepare cores

Carry out scanning

Download data, process, and create output – Image J and OsiriX

Cores extruded Sliced Sampled for:

Bulk density Organic matter content Live root mass and volume

ITM 1-3 UPC 3-3

ITM 1 ITM 2

root and rhizome volume(cc)

-50 0 50 100 150 200 250

dept

h be

low

sur

face

(cm

)

-30

-25

-20

-15

-10

-5

0

root and rhizome biomass(g dry mass)

-2 0 2 4 6 8 10

dept

h be

low

sur

face

(cm

)

-30

-25

-20

-15

-10

-5

0

UPCITM

bulk density(g cc-1)

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

dept

h be

low

sur

face

(cm

)

-30

-25

-20

-15

-10

-5

0

organic matter content(%, dry mass basis)

0 5 10 15 20 25 30 35

dept

h be

low

sur

face

(cm

)

-30

-25

-20

-15

-10

-5

0

ITM 254

320

700

UPC 254

320

700

Reference Material Calibration rod composition Density (g cc-1)

Air plastic pipette with air sealed inside 0.0012

Water plastic pipette with water sealed inside 1.00

34% colloidal silica plastic pipette with 34% colloidal silica sealed inside 1.23

Glass solid glass rod 2.20

Note: All standard density measures are from Weast and Astle (1979) Handbook of Chemistry and Physics except for the colloidal silica (Aldrich Chemical Supply)

Soil fraction Operational definition

Organic Soil at

Indiantown (HU range)

Mineral soil at Upper Phillips

Creek (HU range)

Roots and rhizomes gas < roots and rhizomes < water -930 to 2 -871 to -20

Peat water < peat ≤ 34% colloidal silica 13 to 264 14 to 456

Particulates 34% colloidal silica < particulates < sand 265 to 750 457 to 750

Sand sand < glass 751 to 1200 751 to 1528

Rocks and shells glass < rocks and shells 1201 to 3060 1529 to 3060

CT X-ray attenuation ranges in Hounsfield units (HU) for the soil fractions. HU ranges determined empirically.

Operational definitions of soil fractions based on the CT X-ray attenuation of calibration rods.

Core Components Part Sand Rx&Sh Peat R&R Gas

PCM1

PCM2

PCM3

Core Components Part Sand Rx&Sh Peat R&R Gas

ITM1

ITM2

ITM3

Component Organic soil ITM (% of core volume)

Mineral soil UPC (% of core volume)

gas 0.13 0.19

roots and rhizomes 6.59 2.11

peat 29.34 5.86

particulates 57.19 7.28

sand 5.45 82.75

rocks and shell 0.002 1.56

Component Summary

Core Displacement (fraction core vol)

CT analysis (fraction core vol)

ITM 1 0.06 0.066

ITM 2 0.08 0.077

ITM 3 0.10 0.071

UPC 1 0.04 0.019

UPC 2 0.05 0.021

UPC 3 0.06 0.022

Root volume(cc)

0 50 100 150 200 250

Dep

th b

elow

sur

face

(cm

)

30

25

20

15

10

5

0

ITM1 CTITM1 WDITM2 CT ITM2 WD ITM3 CT IMT3 WD

Roots and Rhizomes Peat

Rocks and Shell Sand Particulates

Phillips

Indiantown

Dashed lines = hand-sorted Solid lines = CT imaging

S. alterniflora aerenchyma Maricle and Lee 2002

Scanner bed

detector

Medical Scanner Resolution = 0.625 mm

Spec-CT Scanner Resolution = 0.050 mm

Medical Scanner Resolution = 0.625 mm

Spec-CT Scanner Resolution = 0.050 mm

ITM 2

Summary • OM contributes to soil volume • Plant roots contribute to soil volume

• To understand contributions more fully, better methods of quantification are required

• CT-imaging maybe a useful alternative

• CT-scanning facility at UVa’s Emily Couric Cancer Center

• Mark Williams, Director SPEC-CT lab • EPA National Health and Environmental

Effects Research Laboratory’s Atlantic Ecology Division

• University of Virginia Anheuser Busch Coastal Research Center

• Virginia Coast Reserve Long Term Ecological Research Program

• National Science Foundation

Acknowledgments