Airborne Scanning

Shaun R. Levick et al: Monitoring the Distribution and Dynamics of an Ivasice Grass in Tropical Savanna Using Airborne LiDAR 04.05.2015

Dr. Jorg M. Hacker, Director and Chief Scientist of Airborne Research Australia / Flinders University has provided us with an article on the spread of an alien invasive grass (gamba grass—Andropogon gayanus) in the tropical savannas of Northern Australia. The invasice grass has a major threat to habitat quality and biodiversity in the region, primarily through its influence on fire intensity. Effective control and eradication of this invader requires better insight into its spatial distribution and rate of spread to inform management actions. We used full-waveform airborne LiDAR data acquired with a RIEGL LMS-Q560 scanner to map areas of known A. gayanus invasion in the Batchelor region of the Northern Territory, Australia.

Our stratified sampling campaign included wooded savanna areas with differing degrees of A. gayanus invasion and adjacent areas of native grass and woody tree mixtures. We used height and spatial contiguity based metrics to classify returns from A. gayanus and developed spatial representations of A. gayanus occurrence (1 m resolution) and canopy cover (10 m resolution). The cover classification proved robust against two independent field-based investigations at 500 m2 (R2 = 0.87, RMSE = 12.53) and 100 m2 (R2 = 0.79, RMSE = 14.13) scale. Our mapping results provide a solid benchmark for evaluating the rate and pattern of A. gayanus spread from future LiDAR campaigns. In addition, this high-resolution mapping can be used to inform satellite image analysis for the evaluation of A. gayanus invasion over broader regional scales. Our research highlights the huge potential that airborne LiDAR holds for facilitating the monitoring and management of savanna habitat condition.

The full article was published under Remote Sens. 2015, 7, 5117-5132, doi: 10.3390/rs70505117 and can be found here.

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