Aridlands Disturbances and Restoration Ecology

Science Center Objects

Desert landscapes are rapidly changing due to increases in invasive plant species, frequency of wildfires, urban and energy development, recreational use, military training, and climate variation. Dr. Todd Esque, USGS researchers, and collaborators are working together to investigate these changes and provide managers with key information that can be used to manage natural resources more effectively.

Nonnative Grass Invasions and Fire in the Arid Ecosystems

Fires in the Mojave and Sonoran deserts were historically infrequent. When fires did occur, gaps of plant-free space separating individual shrubs, bunchgrasses, cacti, and trees, stopped the spread of fires. However, since the 1970s, nonnative grasses have invaded the desert and become increasingly dominant in native plant communities. Increasing grass fuel loads, growing human populations in the arid Southwest, and surface disturbances from many sources have led to more fires, which threaten native plants that are poorly adapted to survive the increasing frequency and intensity of these fires.

The direct effects of fires kill wildlife, but the subsequent changes in their habitats (e.g., loss of vegetation and plant structure) may have more far ranging and long lasting effects on wildlife populations and the recovery of their habitats. WERC researchers are investigating how nonnative annual grasses, increased frequency of fire, and other surface disturbances are changing the face of the North American deserts, their recovery, and experimental restoration techniques. Dr. Todd Esque and USGS scientists are providing managers with key information that can be used to manage natural resources more effectively.

 

Site of an abandoned oil well on the Colorado Plateau of southeastern Utah

Site of an abandoned oil well on the Colorado Plateau of southeastern Utah. This site is recently abandoned and now dominated by Russian thistle, and other weedy species. The large while flowers in the foreground are moonflowers (Datura sp.) another weedy short-lived perennial plant with toxic leaves, flowers, and tubers.  USGS researchers at WERC, SBSC, and FORT are collaborating to provide managers with ways to increase the recovery of native vegetation on abandoned gas and oil wells.(Credit: Todd C. Esque, USGS WERC. Public domain.)

Recovery of Native Vegetation on Abandoned Gas and Oil Well Pads

Dr. Todd Esque is co-leading research into the recovery of vegetation on abandoned gas and oil pads on the Colorado Plateau in Utah with collabortors at USGS-WERC, USGS-SBSC, USGS-FORT, and Texas State University. Abandonment of the sites spans a chronosequence of 80 years across broad environmental gradients of precipitation, temperature, and soils. Changes in vegetation are compared locally to nearby reference sites of relatively undisturbed habitats dominated by sagebrush (Artemisia spp.) or blackbrush (Coleogyne ramosissima). Early results indicate that total plant cover requires about 60 years to recover for blackbrush, but that sagebrush sites do not show recovery after 80 years. However, the dominant species (blackbrush and sagebrush) show very little recovery of the dominant species. Predominance of short-lived woody plants such as snakeweed (Gutierrezia spp.) on these sites may preclude the recovery of the long-lived woody species.  In other systems this process is thought to require centuries. These and other insights will be used to develop restoration prescriptions and initiate restoration research on similar sites on the Colorado Plateau. 

 

Mojave and Sonoran Desert Restoration

By request of Bureau of Land Management (BLM) in Nevada, California, and the National office, USGS is assisting in developing desert restoration programs in the Mojave and Sonoran deserts. Collaborations also exist with restoration programs in the Great Basin and on the Colorado Plateau. This program begins to reclaim vast acreages of desert land lost to desert fire and other disturbances. This project is led in collaboration with USGS’s Dr. Lesley DeFalco and others in BLM, U.S. Fish and Wildlife Service, National Parks Service, and collaborators within academia.

Increasing seed stocks in the greenhouse. Mojave and Sonoran Desert restoration

Increasing seed stocks in the greenhouse for use in the USGS-WERC network of common garden experiments throughout the Mojave Desert. After pollinating individual ecotypes of these sun cup flowers (Chylismia s.) the ripened seeds will be collected and incorporated into an experiment to understand how plants from different populations across the desert function when moved into new environmental conditions of temperature and rainfall.(Credit: Todd C. Esque, USGS WERC. Public domain.)