Michael L. Clutter

Vegetation height derivation from Shuttle Radar Topography Mission data in southeast Georgia, USA

A study was conducted to determine the extent to which data from the 2000 Shuttle Radar Topography Mission (SRTM) can be used to estimate vegetation canopy height in conjunction with an existing bald Earth DEM as provided by the National Elevation Dataset (NED). Intensively managed slash pine stands with canopy heights ranging from 11 to 21 m were biometrically surveyed within the general mission timeframe in early 2000. Results indicate that SRTM data can be successfully correlated via linear regression modeling with ground-measured mean vegetation canopy height at the stand level when mean SRTM-NED height difference measures are extracted by averaging pixels within the stands. Regression analysis using 20 and 50 pixels as stand size thresholds yielded adjusted r2 values of 0.79 and 0.86 with rms errors of 1.1 m and 1.0 m respectively. Thus a minimum SRTM mapping unit of approximately 1.8 hectares can be postulated which allows vegetation canopy height retrieval at the stand scale

Forest parameter retrieval with JPL Airsar P-, L- and C-band data: a plot level analysis for slash pine stands in Georgia

During an EOCAP-SAR project, Airsar P-, L- and C-Band data were used to test the capability of SAR to predict biometric parameters which are frequently used by timber managers as inputs to growth, harvest and yield models. The test site was a commercially managed area in Jesup, south-east Georgia, with stands owned by The Timber Company (TTC). Field campaigns provided an extensive plot-level georeferenced ground data set of four slash pine stands which was used to determine the correlation with the Airsar data. Additionally, 18 stands were surveyed and stand level summaries of biometric variables height, basal area, and volume were obtained. A statistical model was used to test all possible scenarios of polarimetric and frequency combinations. The best models were chosen to develop inversion models for basal area. These model results were applied to stands which are owned by a different timber company (Rayonier), and which were located in the Airsar strip. Within the TTC land holdings, R/sup 2/ correlation coefficients for volume prediction from SAR were 0.85. The correlation between predicted basal area and stand age on 65 Rayonier stands resulted in the an adjusted R/sup 2/ of 0.86.