Tamarisk Beetle

3-Dimensional Classification and Change Detection of Invasive Tamarisk Tree in the Grand Canyon

We use a cutting-edge remote sensing technique to map and detect changes in tamarisk, an invasive tree species in the Grand Canyon. Tamarisk trees are commonly distributed in riparian habitats across the western US. Once established, it can dominate a site by drawing up belowground salts and increasing saline soils that native plant species can not tolerate.

To control tamarisk, a biological control, known as tamarisk beetle (Diorhabda carinulata), was introduced to Colorado, Utah, Wyoming, Nevada, California, and Texas. Tamarisk beetles traveled into Arizona in 2009 and have had substantial impact on tamarisk distribution along the Colorado River.

The extent of its impact and the associated tamarisk decline, however, have not been quantified. Many natural resource management concerns and scientific research questions related to tamarisk defoliation and its impact on the ecosystem (i.e., nutrient cycle, native species recovery) in the Grand Canyon hinge on quantitative estimates of tamarisk decline.

The US Geological Survey (USGS) Grand Canyon Monitoring and Research Center (GCMRC) has acquired airborne, high-resolution 3-dimensional lidar images of Glen Canyon. In collaboration with the USGS scientists, we analyze the lidar data to identify tamarisk trees and classify defoliated and undefoliated tamarisk trees along a continuum of low-to-high canopy openness in Glen Canyon. Along with the lidar data, the USGS provides multi-spectral imagery, field-based tamarisk measurements and maps for classification training and ground-validation. We also further expand the USGS field-based observations through field trips to the Grand Canyon.