International Arid Lands Consortium Investigates a Major Contributor to Wildfires in the Southwestern United States
The International Arid Lands Consortium (IALC) studies the consequences of the invasion of cheatgrass, a non-native species, on the landscapes of the Great Basin
October 23, 2000 (Tucson, AZ)--Water is the focus of The International Arid Lands Consortium (IALC) supported research aimed at explaining how the exotic "cheatgrass" alters ecosystem functions when it invades rangeland that has been over-grazed or ravaged by fire. These consequences include degraded grazing quality and reduced diversity of plants and animals. This non-native grass species is invading grasslands in the southwestern United States. Cheatgrass, a winter annual native of western Europe, has many negative effects on native plant species. It also speeds the spread and frequency of wildfires on rangelands. Scientists at The University of Illinois-Urbana, the Desert Research Institute-Reno, and the Weizmann Institute of Science-Israel, are uniting in a two-year study to develop a better understanding of how the invasion of this exotic grass has altered the hydrology of the Great Basin.
For over a century sagebrush ecosystems of western Nevada have been aggressively invaded by cheatgrass (Bromus tectorum L.). The cheatgrass invasion is propelled by overgrazing and fire. The diverse landscape of shrub-perennial grass steppe is transforming to annual grassland dominated by a single species. This transformation may alter a myriad of ecosystem functions, as cheatgrass growth patterns and rapid distribution across rangelands redistribute water and other physical resources.
The objective of the study is to determine the ecosystem-level consequences of cheatgrass invasion, and remediation practices, on land-area-based energy fluxes and evapotranspiration. Energy flux is the rate at which energy flows. For example, The Watt is a unit of energy flux, because it indicates the amount of energy (in joules) that flows every second. Evapotranspiration occurs when plants secrete or "transpire" water through pores in their leaves. In a way, plants sweat like people do. Specifically, the scientists aim to explore how post-fire replacement of sagebrush communities by cheatgrass alters the spatial and temporal patterns of evapotranspiration and soil moisture. The focus is on water because of its overriding control on reestablishment of native vegetation and other biogeochemical processes.
This research will be conducted in a large intermountain valley near Reno, Nevada, where adjacent communities of intact sagebrush, post-fire cheatgrass, and a post-fire mixture of cheatgrass and crested wheatgrass (Agropyron desertorum) are found on the same soil type. The grass communities established after fire in 1984, and the Bureau of Land Management planted crested wheatgrass in a portion of the burn as part of a reclamation effort. This study will provide the first comprehensive view of how the invasion of an exotic grass has altered the hydrology of western Great Basin sagebrush communities.
Post-fire replacement of sagebrush with cheatgrass continues to degrade the grazing quality and reduce the diversity of plants and animals in the Great Basin. Current reclamation efforts have had very limited success reestablishing shrub steppe. Quantifying the effects of cheatgrass on the evapotranspiration and soil water will provide an important foundation for future experiments designed to determine successional sequences after fire in the Great Basin, and to design appropriate strategies for restoring native sagebrush communities after large-scale disturbance.
Support for this project came from the USDA Forest Service.
The International Arid Lands Consortium (IALC) is an independent nonprofit organization dedicated to exploring the problems and solutions unique to arid and semiarid regions. IALC promotes cooperative research and practical application of new knowledge to develop sustainable ecological practices. The member institutions and their affiliates share a mission to enable people of arid lands to improve the quality of life for future generations. IALC members include the University of Arizona, Desert Research Institute-Nevada, the University of Illinois, Jewish National Fund, New Mexico State University, South Dakota State University, Texas A&M University-Kingsville, and the Higher Council for Science & Technology-Jordan. The Ministry of Agriculture & Land Reclamation-Egypt is an affiliate member.
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