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.
1. Reduction of cheatgrass and development of potential new agricultural products. Scientists in the Exotic and Invasive Weeds Research Unit in Reno, Nevada conducted basic research on the possibility of using seeds from the invasive annual grass cheatgrass as a new grain for use in producing food and beverages. Preliminary work was initiated on appropriate techniques to harvest, process, and malt cheatgrass as a grain source for brewing beer. The seeds were collected as part of a project to mechanically remove the annual grass seed source and reduce the cheatgrass sandbank so that native plant species can be successfully reestablished. If harvested properly, it can reduce fuel loads by creating green stripes thereby reducing the probability of catastrophic wildfires. Removal of cheatgrass seeds, a major invasive annual grass in the intermountain west, has the potential to aid in ecosystem restoration. The beer produced by fermentation of cheatgrass seeds has been judged to be of good quality and could increase the economic viability of cheatgrass-infested ecosystems. This research successfully demonstrated that cheatgrass seeds are a viable source of grain for use in agricultural products and that commercial vendor would purchase the seed if available. No further work is planned at this time as it has been successfully demonstrated that cheatgrass seeds are a viable protein source in producing agricultural food products.
2. Introduced plants may help reduce cheatgrass in the Great Basin. Scientists in the Exotic and Invasive Weeds Research Unit in Reno, Nevada have documented that crested wheatgrass can effectively suppress cheatgrass. The team tested the hypothesis that crested wheatgrass reduces available mineral soil N to levels below which cheatgrass is competitive. Relative to other ecosystems tested, soil beneath crested wheatgrass does not have appreciably lower mineral N. Surprisingly, the molar proportion of ammonium-N in the total mineral pool is quite high in the tested crested wheatgrass ecosystem, averaging 84% throughout the year. Further studies are underway to reduce the competitiveness of cheatgrass.
3. Small mammals do heavy lifting in restoring Great Basin rangelands. Scientists in the Exotic and Invasive Weeds Research Unit in Reno, Nevada have found that desert rodents can have profound impacts on specific plant species and on species composition of arid plant communities. Buried, scattered seed caches made by rodents accounted for 95% of seedling production of the native grass, Indian ricegrass which is a critical forage resource for livestock and wildlife. These animals cache seeds near the ground surface with the full intention of returning during seasons of seed shortages to later consume the cached seeds. Only seeds that escape this subsequent re-harvesting for consumption can germinate the following spring. It is possible to enhance the beneficial effects of a seed-caching rodent species of native plant species by providing inexpensive commercially available, “diversionary” seeds that are highly desirable to the rodents. Rodents would then cache both seed types but preferentially recover the preferred diversionary seeds before beginning to consume the less desirable native plant species seeds. Consequently, more native plant seeds are available for emergence as seedlings using this passive and inexpensive restoration scheme.
4. Reducing the cost in restoring Great Basin Rangelands. Scientists in the Exotic and Invasive Weeds Research Unit in Reno, Nevada have developed techniques of increasing the success of restoration/revegetation practices of cheatgrass invaded rangelands. These techniques on average cost $119.75/ac during the first year. However, if treatments are delayed until the second year costs goes up to $207.95 and success is significantly less. The long term result would be healthy rangelands.
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.