Field Measurements of Leaf Field Measurements of Leaf Mass Area (LMA) in Support Mass Area (LMA) in Support of Remote Sensing Studies of of Remote Sensing Studies of a Pacific Northwest Old a Pacific Northwest Old Growth Forest CanopyGrowth Forest Canopy

Katie Berger (UMASS-Amherst)Katie Berger (UMASS-Amherst)Research & Discover Intern 2005Research & Discover Intern 2005Advisor: Barry RockAdvisor: Barry RockANDANDScott OllingerScott OllingerMary MartinMary Martin

http://www.riegl.com/distancemeters_/distancemeter_applications_/notes_/e_ps085.htm

OutlineOutline

Importance of LMA in forestsImportance of LMA in forests ApplicationsApplications Background of Wind RiverBackground of Wind River MethodsMethods ResultsResults NASA OutreachNASA Outreach

ImportanceImportance What is LMA?What is LMA?

Leaf Mass Area: Ratio of leaf dry mass in canopy per unit Leaf Mass Area: Ratio of leaf dry mass in canopy per unit area area

Leaf Area Index: Ratio of area of leaves in canopy per unit Leaf Area Index: Ratio of area of leaves in canopy per unit area of ground surfacearea of ground surface

Why study Leaf Mass Area (LMA)?Why study Leaf Mass Area (LMA)? Less research has been done; tedious to determine LMALess research has been done; tedious to determine LMA Future research in understanding forest ecosystems: Future research in understanding forest ecosystems:

Nitrogen & net photosynthesis modeling, using ecological Nitrogen & net photosynthesis modeling, using ecological models and remote sensingmodels and remote sensing

Most importantly:Most importantly: Indicative of environmental conditions and growth rates of Indicative of environmental conditions and growth rates of

foliagefoliage To parameterize ecological models of forest ecosystemsTo parameterize ecological models of forest ecosystems To calibrate remote sensing imagesTo calibrate remote sensing images

Ex: mapping canopy chemistryEx: mapping canopy chemistry

Indicating Environmental Indicating Environmental ConditionsConditions

LMA strongly correlated LMA strongly correlated to foliar N and net to foliar N and net photosynthesis of the photosynthesis of the tree canopytree canopy

Can help researchers Can help researchers predict the net predict the net growth/health of forest growth/health of forest

http://www.pnas.org/cgi/reprint/94/25/13730

(Reich et al., 1997)

Ecosystem ModelsEcosystem Models

Where remote sensing can give us a global Where remote sensing can give us a global view of reflectance properties, ecological view of reflectance properties, ecological models can give us better insight on the models can give us better insight on the processes that are going on processes that are going on withinwithin the the ecosystemecosystem

PnET-Day (a program designed by scientists at PnET-Day (a program designed by scientists at UNH) is an ecological modeling program that UNH) is an ecological modeling program that incorporates foliar mass, LMA, foliar N incorporates foliar mass, LMA, foliar N concentration, temperature and radiation flux to concentration, temperature and radiation flux to predict daily and net photosynthesis of entire predict daily and net photosynthesis of entire forest canopies forest canopies

Calibrating Remote Calibrating Remote Sensing ToolsSensing Tools

Ground work makes Ground work makes sense of satellite images sense of satellite images by showing differences by showing differences in field observations that in field observations that cannot be identified cannot be identified through remote sensing through remote sensing techniquestechniques

Gives researchers Gives researchers tangible data to correlate tangible data to correlate to satellite imageryto satellite imagery

http://www.ucalgary.ca/UofC/faculties/SS/GEOG/Virtual/Remote%20Sensing/multistage.gif

Wind River Canopy Crane Wind River Canopy Crane Research FacilityResearch Facility

Western old growth Western old growth forestforest

Dominant speciesDominant species Douglas fir (PSME)Douglas fir (PSME) Western hemlock (TSHE)Western hemlock (TSHE) Pacific silver fir (ABAM)Pacific silver fir (ABAM) Western red cedar Western red cedar

(THPL)(THPL)

Located in southern Located in southern Washington, USAWashington, USA

http://research.eeescience.utoledo.edu/lees/pubs/Roberts04.pdf

WRCCRF July 1998

(Roberts et al., 2004)

Canopy CraneCanopy Crane

Canopy crane was used to gather foliar samples from Canopy crane was used to gather foliar samples from known heights/trees in the canopyknown heights/trees in the canopy

At its max lift and reach capacity, the crane can cover a At its max lift and reach capacity, the crane can cover a cylindrical volume of over 54 million cubic feet; cylindrical volume of over 54 million cubic feet; reaching over 300 trees accessible via use of the reaching over 300 trees accessible via use of the gondola. gondola.

http://depts.washington.edu/wrccrf/crane.html

Methods for Measuring Methods for Measuring LMALMA

All measurement methods are imperfect All measurement methods are imperfect due to needle complexity and variabilitydue to needle complexity and variability

Two methods used in published data:Two methods used in published data: Volume displacementVolume displacement Optical Scanning Optical Scanning

Volume Displacement Volume Displacement MethodMethod

Immersed in HImmersed in H22OO Displaced volume recorded by Displaced volume recorded by

massmass Needles counted & measuredNeedles counted & measured Volume to area conversion:Volume to area conversion:

Ex: Area (elliptical cross-Ex: Area (elliptical cross-section) = 0.5section) = 0.5√((3.14)x) * √((3.14)x) * (1+1/x) * √(Vnl) (1+1/x) * √(Vnl) (Chen et al., 1997)(Chen et al., 1997)

Completed for a total of over 50 Completed for a total of over 50 samplessamples

Potential weaknessesPotential weaknesses Too many measurements: too Too many measurements: too

many sources of errormany sources of error

CLIP

H2O + Detergent

Cross-section Cross-section of a Western of a Western Hemlock Hemlock

Optical Scanning MethodOptical Scanning Method

Foliage scanned on a Foliage scanned on a flat bed scanner flat bed scanner

Image processing to Image processing to remove shadowsremove shadows

Convert to LMA using Convert to LMA using dry weight valuesdry weight values

Potential weaknessesPotential weaknesses Difficulty in removing Difficulty in removing

edge effects/shadow edge effects/shadow

Vertical Gradients in Vertical Gradients in LMA: Displacement LMA: Displacement MethodMethod

Deviation from the Deviation from the mean LMA for both mean LMA for both species suggest that species suggest that there is a trend of there is a trend of increasing LMA with increasing LMA with increase in height increase in height through the canopythrough the canopy

This counters This counters assumptions used in assumptions used in several modelsseveral models

R2 = 0.2444

R2 = 0.0568

0

50

100

150

200

250

0 10 20 30 40 50 60

Height of Sample(m)

LM

A (

g/m2

)

Douglas Fir

Western Hemlock

R2 = 0.0649

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 10 20 30 40 50 60

Height of Sample (m)

Devia

tion fro

m M

ean L

MA

Comparison of MethodsComparison of Methods

Trends stronger with Trends stronger with optically scanned optically scanned methodmethod

Optically scanned Optically scanned produced higher LMA produced higher LMA valuesvalues

Optically Scanned vs. Displaced LMA (PSME)

R2 = 0.1199

R2 = 0.4632

0

50

100

150

200

250

300

0 10 20 30 40 50 60

Height of Tree Sample (m)

LM

A (

g/m

^2^

)

lma PSME opt

lma PSME dis

Optically Scanned vs. Displaced LMA (TSHE)

R2 = 0.4564

R2 = 0.0556

0

50

100

150

200

250

300

0 10 20 30 40 50 60

Height of Tree Sample (m)

LM

A (

g/m

^2^

)lma THSE opt

lma TSHE dis

More Research NeededMore Research Needed

Does increase of LMA with height trend Does increase of LMA with height trend depend on method of LMA used?depend on method of LMA used?

More research will be needed to More research will be needed to determine thisdetermine this

Implications of future researchImplications of future research

Applying Gradient to Applying Gradient to Ecosystem ModelsEcosystem Models

PnET Model Results for Wind River Flux Tower

0

2

4

6

8

10

12

14

0 50 100 150 200 250 300 350 400

Day Of Year 2004

GC

E (

g m-2

yr-1)

No LMA Gradient(1717 gC m-2 yr)

With LMA Gradient(1577 gC m-2 yr-1)

Measured Value: 1550-1590 gC m-2 yr-1 (From Paw et al. 2004)

Applying Gradient to Applying Gradient to Ecosystem ModelsEcosystem Models

PnET Model Results for Wind River Flux Tower

0

2

4

6

8

10

12

14

0 50 100 150 200 250 300 350 400

Day Of Year 2004

GC

E (

g m-2

yr-1)

No LMA Gradient(1717 gC m-2 yr)

With LMA Gradient(1577 gC m-2 yr-1)

Measured Value: 1550-1590 gC m-2 yr-1 (From Paw et al. 2004)

Future ResearchersFuture Researchers

AcknowledgementsAcknowledgements

Thanks Thanks Any questions?Any questions?

Special thanks to:Special thanks to:Barry RockBarry RockMary MartinMary Martin

Scott OllingerScott OllingerGeorge HurttGeorge Hurtt

The Forest Ecosystems LabThe Forest Ecosystems LabProject SmartProject Smart

Everyone else who has helped me out along the way @ EOSEveryone else who has helped me out along the way @ EOSAnd The Research & Discover Program (UNH-NASA) for providing And The Research & Discover Program (UNH-NASA) for providing

me with this great opportunityme with this great opportunity

Work CitedWork Cited

Chen, Jing, et al. “Leaf Area Index of Boreal Forests: Chen, Jing, et al. “Leaf Area Index of Boreal Forests: Theory, Techniques, and Measurements” Theory, Techniques, and Measurements” Journal of Journal of Geophysical Research Geophysical Research 102 (1997):29,429-29,443102 (1997):29,429-29,443

Reich, Peter, et al. “From Tropics to Tundra: Global Reich, Peter, et al. “From Tropics to Tundra: Global Convergence in Plant Functioning” Convergence in Plant Functioning” Proceedings of the Proceedings of the National Academy of Sciences of the United States of National Academy of Sciences of the United States of America America 94 (1997): 13730-1373494 (1997): 13730-13734

Roberts, Dar, et al. “Spectral and Structural Measures of Roberts, Dar, et al. “Spectral and Structural Measures of Northwest Forest Vegetation at Leaf to Landscape Northwest Forest Vegetation at Leaf to Landscape Scales” Scales” EcosystemsEcosystems 7 (2004): 545-562 7 (2004): 545-562