PARENT SESSION
Poster Session # 5: GIS and Remote Sensing.
Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Improved ground- and satellite-based methods for deriving LAI in a burned ponderosa pine ecosystem.
Smith, Rachel*,1, Vierling, Lee1, 1 South Dakota School of Mines and Technology, Rapid City, South Dakota
ABSTRACT- The purpose of our study is to conduct a series of field measurements and data analyses to investigate the accuracy and various potential improvements of leaf are index (LAI) derivations from satellite sensors over a ponderosa pine dominated forest. Permanent field sites were established within and around the 33,800 hectare Jasper fire (burned September 2000), in the southwestern Black Hills of South Dakota. Spatial variation in fire severity resulted in a heterogeneous mosaic of canopy LAI and therefore sites were selected to represent a continuum of LAI values. To account for the nonrandom nature of ponderosa pine stands and for the effects of clumping at various scales, correction factors were applied to the effective LAI values obtained from a LAI-2000 Plant Canopy Analyzer and hemispherical photos. Clumping indices from the needle and shoot scales were applied from previous LAI studies conducted on ponderosa pine in Oregon. A Tracing Radiation and Architecture (TRAC) instrument was used to correct for clumping at scales larger than shoot. Corrected and uncorrected LAI values were then regressed against spectral vegetation indices (SVIs) derived from IKONOS, Landsat ETM+, and MODIS data. Uncorrected effective LAI values were better correlated with SVIs (e.g. r2 = 0.51 for IKONOS NDVI comparisons) than after the LAI values were corrected for clumping (r2 = 0.18), indicating the need for site specific clumping correction indices. To address this issue, we explored the use of ground-based Light Detection and Ranging (LiDAR) data as a substitute for destructive sampling to derive clumping indices at the needle and shoot scales.
Key words: ponderosa pine, leaf area index, fire