Thomas B Christiansen* - The University of Texas at Austin
Kelley A Crews, The University of Texas at Austin -
Thoralf Meyer, The University of Virginia -
Field structural measurements were collected in a savanna system proximate to the Okavango Delta in the Botswana Kalahari. Three study sites were surveyed along multiple transects perpendicular to water / village locations with 10 x 25 m plots oriented along each transect at regular intervals. Each tree (7472 in total) was identified and measured with respect to stem and canopy dimensions. Three-dimensional visualizations of these plots were created using IDL. The visualizations allow interpretation and communication of structural differences among plots on a given transect, among all plots within a given site, and across sites as well as interpreted in light of distance to water, populated areas, and recent disturbances. Plots were categorized into disturbance classes, and then compared to three other data sources. First, the disturbance classes were compared to high resolution (GeoEye) imagery to determine the success of categorization and how representative both individual plots and transects were of the greater region. Second, the disturbance classes were qualitatively compared to interviews conducted in the three study sites to assess correlation among reports of extraction of veld products and land management. Third, aboveground biomass was calculated for each plot using collaborators' allometric equations derived from a dataset of 342 harvested trees and shrubs in Western Botswana relating basal area and crown diameter to aboveground biomass. These calculations were then compared at the disturbance class level to illustrate the utility of disturbance classes as explicitly linking field- and satellite-derived measurements as each providing important quantifiable indicators of savanna disturbance.