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LEAF AREA INDEX (LAI) CHANGE DETECTION ANALYSIS ON LOBLOLLY PINE (PINUS TAEDA) FOLLOWING COMPLETE UNDERSTORY REMOVAL
Citation:
IIAMES, J. S., R. CONGALTON, A. N. PILANT, AND T. E. LEWIS. LEAF AREA INDEX (LAI) CHANGE DETECTION ANALYSIS ON LOBLOLLY PINE (PINUS TAEDA) FOLLOWING COMPLETE UNDERSTORY REMOVAL. PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING. American Society for Photogrammetry and Remote Sensing, Bethesda, MD, 74(11):1389 - 1400, (2008).
Impact/Purpose:
Our research objectives are to: (a) develop new methods using satellite remote sensor data for the rapid characterization of LC condition and change at regional to national scales; (b) evaluate the utility of the new NASA-EOS MODIS (Moderate Resolution Imaging Spectrometer) leaf area index (LAI) measurements for regional scale application with landscape process models (e.g., biogenic emissions and atmospheric deposition); (c) provide remote sensor derived measurement data to advance the development of the next generation of distributed landscape process-based models to provide a predictive modeling capability for important ecosystem processes (e.g., nutrients, sedimentation, pathogens, etc.); and (d) integrate in situ monitoring measurement networks with UAV and satellite based remote sensor data to provide a continuous environmental monitoring capability.
Description:
The confounding effect of understory vegetation contributions to satellite-derived estimates of leaf area index (LAI) was investigated on two loblolly pine (Pinus taeda) forest stands located in Virginia and North Carolina. In order to separate NDVI contributions of the dominantcodominant crown class from that of the understory, two P. taeda 1-ha plots centered in planted
stands of ages 19 and 23 years with similar crown closures (70%) were analyzed for in situ LAI and NDVI differences following a complete understory removal at the peak period of LAI. Understory vegetation was removed from both stands via mechanical harvest and herbicide application in late July and early August 2002. IKONOS data was acquired both prior and subsequent to understory removal and were evaluated for NDVI response. Total vegetative biomass removed under the canopies was estimated using the Tracing Radiation and Architecture of Canopies (TRAC) instrument combined with digital hemispherical photography (DHP). The
Virginia site results showed that the percentage of removed understory (LAI) detected by the IKONOS sensor was 4.7% when compared to an actual in situ LAI reduction of 9.9%. The North Carolina site results showed a smaller percentage of understory LAI detected by the IKONOS
sensor (1.0%) when compared to the actual LAI reduction as measured in situ (17.6%).