Location: Great Basin Rangelands Research2010 Annual Report
1a. Objectives (from AD-416)
The Integrated Invasive Species Control, Revegetation, and Assessment of Great Basin Rangelands project has two objectives: 1) Identify and characterize biotic and abiotic conditions and processes that affect plant community factors and ecosystem dynamics on healthy and degraded rangelands to improve the ability to predict how rangelands will respond to changing environmental conditions and alternative management practices and 2) Devise management guidelines, technologies, and practices for conserving and restoring Great Basin rangelands.
1b. Approach (from AD-416)
The research project is organized into four complementary components: (1) ecology and control of invasive plants, (2) revegetation of degraded rangelands, (3) maintaining and/or enhancing healthy rangelands, and (4) quantifying economic and environmental impacts of management practices at the landscape scale. Experiments will be conducted to understand the seed and seedbed ecology of several native and non-native grasses and shrubs. Herbicides and tillage will be used to vary content of competing vegetation as it affects shrub establishment. Research will be conducted to document ecological processes which control expansion of Western Juniper. Levels of genetic variation of selected plants will be compared between high and low quality ecological conditions sites to determine effects of disturbance on genetic diversity. Rainfall simulators will be used to characterize runoff and soil erosion processes at the scale of a plant community under different manipulative treatments (altered grazing practices, burning, and brush removal) to quantify the hydrologic impact of the conservation practices. The SWAT model will be utilize to evaluate which alternative management scenarios (i.e., a change in vegetation state as represented by changes in canopy and ground cover or vegetation composition by life form) are the most cost effective in achieving the desired environmental benefit. Replaces 5325-11220-005-00D (2/09).
3. Progress Report
The USDA team working on CEAP has developed a new process based model for assessing soil erosion rates on rangelands. The Rangeland Hydrology and Erosion Model (RHEM) was developed based exclusively on data collected from rangeland erosion experiments. RHEM is designed to use data that is routinely collected by range managers and the model can be accessed through the internet to develop fast and efficient recommendation on which conservation practices are the most cost efficient for achieving a targeted reduction in soil loss. RHEM has been adopted by the Natural Resources Conservation Service for use in calculating runoff and soil erosion at the hillslope scale. Efforts are currently underway to apply RHEM at 10,000 NRCS National Resource Inventory (NRI) sampling sites as a means of producing the first national assessment of soil loss on rangelands for the USDA Resource Conservation Assessment report due to Congress in December 2010. Research was initiated to focus on the potential of using native annual forbs to increase establishment of early successional native perennial species in cheatgrass invaded rangelands. Species that germinate in the fall, with cheatgrass, are able to accumulate biomass and establish roots that might provide a competitive advantage relative to spring germinators. Native annual species that were observed to be part of the post-disturbance flora in Wyoming sagebrush plant communities in western Nevada were selected for evaluation. The results of this research will lead into future work focusing on the facilitative effects of early seral grass and forb species on the successful restoration of desired shrubs and longer-lived perennial grasses and forbs, into disturbed plant communities. This unit has collected the last phase of data that will lead to guidelines to revegetate habitats disturbed by wildfire. The data clearly shows that rangelands that burn are much more likely to be successfully revegetated the 1st fall following the wildfire than waiting until the 2nd year. Using specific plant species is also necessary to compete with and suppress cheatgrass densities. As part of the Sagebrush Steppe Treatment Evaluation Project, ARS scientists have quantified soil carbon stocks and the effect of several restoration treatments on these stocks in several sagebrush and pinyon-juniper ecosystems in Idaho, Oregon, Utah, and Nevada. Data are presently being analyzed and should determine the potential of these ecosystems to store anthropogenic carbon dioxide. Juniper berry removal experiments at 3 northern California sites were initiated to investigate seed dispersal and seedling recruitment in western juniper populations. Juniper berry production was estimated for all trees on 1-ha study plots at each of these sites, and a new study was initiated to identify insect seed predators and quantify their effects on juniper seed viability. Annual small mammal trapping and bird surveys were established at each site and automated wildlife cameras were deployed at 2 sites. This has resulted in identification of at least 5 small mammal and 4 bird species that consume juniper berries and potentially disperse seeds.
5. Significant Activities that Support Special Target Populations
The Research Unit worked with the University of Nevada at Reno to host the third annual workshop on jobs in natural resources for Piute tribe high school students. During the one week summer workshop the high school students were provided an overview of jobs in natural resources on the first day and a tour of ARS and University of Nevada at Reno research facilities. On each of the following days the students were hosted by a scientist who took them to the field to demonstrate different techniques to measure abiotic and biotic parameters used to define watershed health within the Truckee river basin. Most research conducted through this research project is in support of small farms and/or ranches that need economically viable methods of controlling invasive weeds and sustainably managing Great Basin rangelands. In particular we work closely with ranchers in Northern California and Nevada on control of salt cedar, cheatgrass and management issues related to pinyon-juniper woodlands. Through our outreach program and sponsorship of conferences and workshops over 500 people have been engaged with the project and have learned about our rapidly developing new technology and techniques to mange Great Basin rangelands.