National Wildlife Refuge System
Airborne lidar can be processed to yield a broad array of forest canopy structure metrics that are important for wildlife management. For golden-cheeked warblers at Balcones Canyonlands National Wildlife Refuge near Austin, Texas, the amount of canopy cover greater than or equal to 1 m turned out to be an important predictor of population density. The draft Habitat Management Plan for the Refuge is incorporating this knowledge by including an objective to increase canopy cover at this level across the 7,500 ha of juniper-oak woodlands managed for this species. The successional stage of each refuge tract was assessed from the lidar-derived canopy cover layer using zonal statistics in ArcGIS. Canopy cover greater than 80 percent (i.e., the highest quality habitat) was found over about 45 percent of the warbler management areas. About 22 percent of the warbler management areas have canopy cover between 60 and 80 percent, indicating a successional vegetation stage, and the remaining third hosted lower quality habitat. These analyses are critical for helping management know where to focus efforts to maximize growth of diverse juniper-oak woodlands.
A tract with low to medium canopy cover and a mid-successional vegetation stage on the left, and one with high canopy cover and high-quality golden-cheeked warbler habitat on the right.