Three-dimensional woody vegetation structure across different land-use types and land-use intensities in a semi-arid savanna

Abstract

Factors influencing woody savanna vegetation structure across a land-use gradient of intensity (highly and lightly utilized communal rangeland) and type (national protected area, private game reserve and communal rangelands) were investigated. Small footprint discrete return LiDAR data (1.12 m point spacing) from the Carnegie Airborne Observatory (CAO) ‘Alpha system’ were used to measure three-dimensional vegetation structure across the different treatments. A volumetric pixel (voxel) approach was used to characterise the vertical distribution of LiDAR returns, that is, vegetation density, in one metre increments for comparison using descriptive statistics across the land-use type and intensity gradient. Vegetation structure in the national protected area was most similar to the lightly utilized rangelands, and the private game reserve was most similar to the highly utilized rangelands with low levels of structural diversity present. Current trends in structural diversity can be related to harvesting, regeneration, herbivory and fire.