Field Measurements of Leaf Mass Area (LMA) in Support of Remote Sensing Studies of a Pacific Northwest Old Growth Forest Canopy Katie Berger (UMASS-Amherst) Research & Discover Intern 2005 Advisor: Barry Rock AND Scott Ollinger Mary Martin

Outline  Importance of LMA in forests  Applications  Background of Wind River  Methods  Results  NASA Outreach

Importance  What is LMA?  Leaf Mass Area: Ratio of leaf dry mass in canopy per unit area  Leaf Area Index: Ratio of area of leaves in canopy per unit area of ground surface  Why study Leaf Mass Area (LMA)?  Less research has been done; tedious to determine LMA  Future research in understanding forest ecosystems: Nitrogen & net photosynthesis modeling, using ecological models and remote sensing  Most importantly:  Indicative of environmental conditions and growth rates of foliage  To parameterize ecological models of forest ecosystems  To calibrate remote sensing images  Ex: mapping canopy chemistry

Indicating Environmental Conditions  LMA strongly correlated to foliar N and net photosynthesis of the tree canopy  Can help researchers predict the net growth/health of forest (Reich et al., 1997)

Ecosystem Models  Where remote sensing can give us a global view of reflectance properties, ecological models can give us better insight on the processes that are going on within the ecosystem  PnET-Day (a program designed by scientists at UNH) is an ecological modeling program that incorporates foliar mass, LMA, foliar N concentration, temperature and radiation flux to predict daily and net photosynthesis of entire forest canopies

Calibrating Remote Sensing Tools  Ground work makes sense of satellite images by showing differences in field observations that cannot be identified through remote sensing techniques  Gives researchers tangible data to correlate to satellite imagery 0Sensing/multistage.gif

Wind River Canopy Crane Research Facility  Western old growth forest  Dominant species  Douglas fir (PSME)  Western hemlock (TSHE)  Pacific silver fir (ABAM)  Western red cedar (THPL)  Located in southern Washington, USA WRCCRF July 1998 (Roberts et al., 2004)

Canopy Crane  Canopy crane was used to gather foliar samples from known heights/trees in the canopy  At its max lift and reach capacity, the crane can cover a cylindrical volume of over 54 million cubic feet; reaching over 300 trees accessible via use of the gondola.

Methods for Measuring LMA  All measurement methods are imperfect due to needle complexity and variability  Two methods used in published data:  Volume displacement  Optical Scanning

Volume Displacement Method  Immersed in H 2 O  Displaced volume recorded by mass  Needles counted & measured  Volume to area conversion:  Ex: Area (elliptical cross- section) = 0.5√((3.14)x) * (1+1/x) * √(Vnl) (Chen et al., 1997)  Completed for a total of over 50 samples  Potential weaknesses  Too many measurements: too many sources of error CLIP H 2 O + Detergent Cross-section of a Western Hemlock

Optical Scanning Method  Foliage scanned on a flat bed scanner  Image processing to remove shadows  Convert to LMA using dry weight values  Potential weaknesses  Difficulty in removing edge effects/shadow

Vertical Gradients in LMA: Displacement Method  Deviation from the mean LMA for both species suggest that there is a trend of increasing LMA with increase in height through the canopy  This counters assumptions used in several models

Comparison of Methods  Trends stronger with optically scanned method  Optically scanned produced higher LMA values

More Research Needed  Does increase of LMA with height trend depend on method of LMA used?  More research will be needed to determine this  Implications of future research

Applying Gradient to Ecosystem Models Measured Value: gC m-2 yr-1 (From Paw et al. 2004)

Applying Gradient to Ecosystem Models Measured Value: gC m-2 yr-1 (From Paw et al. 2004)

Future Researchers

Acknowledgements Thanks Any questions? Special thanks to: Barry Rock Mary Martin Scott Ollinger George Hurtt The Forest Ecosystems Lab Project Smart Everyone else who has helped me out along the EOS Everyone else who has helped me out along the EOS And The Research & Discover Program (UNH-NASA) for providing me with this great opportunity

Work Cited Chen, Jing, et al. “Leaf Area Index of Boreal Forests: Theory, Techniques, and Measurements” Journal of Geophysical Research 102 (1997):29,429-29,443 Reich, Peter, et al. “From Tropics to Tundra: Global Convergence in Plant Functioning” Proceedings of the National Academy of Sciences of the United States of America 94 (1997): Roberts, Dar, et al. “Spectral and Structural Measures of Northwest Forest Vegetation at Leaf to Landscape Scales” Ecosystems 7 (2004):