Research Projects

Water releases used to optimize hydropower production from Glen Canyon Dam have increased baseflow in Grand Canyon which allowed invasive tamarisk tree (Tamarix spp.) to establish on its historically barren sandbars, introducing a completely new ecosystem to one of the most well known stretches of the Colorado River. This new forest provided many benefits to wildlife, especially for endangered migratory birds. In 2001, tamarisk beetles (Diorhabda carinulata) were introduced to the United States in an attempt to quell the widespread tamarisk invasion and unexpectedly expanded into Grand Canyon by 2009. Since then, the canyon’s tamarisk canopies have experienced almost a 30% reduction that is likely to continue, negating the new benefits to wildlife. While the situation introduces a large risk that this novel ecosystem will collapse, it also provides an opportunity to reshape Grand Canyon’s new riparian forest as a novel, but native-centered, ecosystem. The Fremont Cottonwood (Populus fremontii), a keystone native riparian tree, is unique in the magnitude and variety of benefits that it provides to humans, wildlife, and river form. The tree’s reproduction depends heavily on its seeds being transported downstream by large spring floods. These floods only occur during high flow experiments (HFE’s) that are synced with large sand influxes from the Paria River, a tributary, to rebuild sandbars used by rafters for campsites. Here, we use USGS water elevation data and a literature review of regional cottonwood characteristics to explore how strategic adjustments to HFE designs can potentially promote cottonwood germination in Grand Canyon, continuing the benefits to local wildlife and migratory species while transitioning to a riparian forest that is resistant to damages from the tamarisk beetle.