2008 Annual Report
1a.Objectives (from AD-416)
To investigate a wide range of factors controlling the natural and artificial recruitment of new plants to temperate desert rangeland communities. The purpose of these investigations is to increase the efficiency and reduce the cost of range improvement, weed control, and restorations. Develop integrated, biologically based weed control methods including classical biological control for selected invasive weeds such as tamarisk. Develop stand renewal processes for native plants. Work with Burns, Oregon unit to develop management systems for sustainable rangelands.
1b.Approach (from AD-416)
Various criteria will be developed for the identification of high ecological condition range sites in the temperate desert ranges of the Great Basin. Animals representing different taxa and functional groups will be used. Granivorous rodents, which in addition to being abundant and very specious, have major effects on seedling establishment dynamics; diurnal lizards, which are diverse and important insect predators; and ground and foliage dwelling insects, which include both habitat generalists and a variety of very specialized species representing various trophic levels that might be good indicators of ecological status, will be studied. Also, levels of genetic variation of selected plants and animals will be compared between high and low ecological condition sites to determine effects of disturbance on genetic diversity. Experiments will be conducted to understand the seed and seedbed ecology of several native and non-native shrubs. Herbicides and tillage will be used to vary content of completing vegetation as it affects shrub extablishment success. Replacing 5325-11220-002-00D (8/07).
Some of the research conducted during FY2008 involved continuation or extension of work initiated under the past CRIS project. For example, we continue to monitor the invasion of a winterfat community by cheatgrass. Many soil attributes have been measured to quantify the effect of cheatgrass invasion on soil nutrient availability. It is clear from this study that cheatgrass modifies the soil to increase availability of nitrogen and phosphorus relative to non-invaded sites. We also completed a study on 8 sites in northern Nevada and northeastern California in which individual and combinations of Fe, Cu, Zn, Mn, Fe, Ni, and Ag were applied to decrease enzyme activities associated with N-mineralization. We then monitored cheatgrass density and soil nutrient availability of N. At all sites, micronutrient additions have not decreased N availability or cheatgrass density relative to control plots. We continued to monitor through 2007, but micronutrient additions, at the rates applied, did not suppress cheatgrass density. This research supports the NP 205 (215) Component entitled “Integrated Management of Weeds and Other Pests.”
In addition to extended research from the past research project plan, we began pursuing milestones relative to proposed sub-objectives in the new project plan that is currently undergoing ad hoc review. Bridging CRIS activities addressed the following sub-objectives in the new project plan:
Quantify how invasive plants alter biogeochemical cycling, soil nutrient availability, and the vertical distribution of nutrients in the soil profile:
In cooperation with University of Nevada collaborators, we conducted a field study that quantified above-and below-ground carbon stocks in pinyon-juniper ecosystems treated with prescribed fire. Data will clarify the potential of semi-arid woodlands to sequester carbon and the effect of prescribed fire on carbon stocks.
Determine mechanisms underlying the expansion of native western juniper (Juniperus occidentalis) woodlands:
Three study sites were identified in northern California for long-term study of the roles of seed dispersal and seedling recruitment in the ongoing expansion of western juniper woodlands. We conducted small mammal trapping and bird surveys and deployed Trailmaster® automated wildlife cameras to identify potentially important seed dispersing animals. We also initiated a seed trap study at the new sites to begin quantifying levels of seed predation in western juniper.
Provide management guidelines and techniques for establishing and enhancing native and introduced grasses, forbs, and shrubs in shrub-steppe and desert ecosystems:
We investigated the techniques of drill and broadcast seeding of a variety of desirable native and introduced species to suppress cheatgrass and decrease fuel loads that will result in decreased wildfire frequencies. By discing the site to bury the majority of cheatgrass seeds to a depth that would not allow seedling emergence, we decreased cheatgrass densities from 92/ft² down to 26/ft². This resulted in the establishment of desirable seeded species from 1.8/ft² in the undisced plots up to 4.4/ft² in the disced plots.
Biogeochemistry and plant invasion. To determine how the invasive weed cheatgrass affects nutrient availability to desirable range forage plants, the Reno, NV Exotic and Invasive Weeds Research unit quantified elemental fluxes and soil nutrient pools at sites representing three invasion classes:.
2)invaded for three years by cheatgrass,.
3)invaded for 10 years by cheatgrass. Compared to non-invaded sites, 10 years of cheatgrass invasion resulted in significantly greater plant biomass, a significantly greater flux of carbon and a significant decrease in flux of calcium. Plots invaded by cheatgrass for 10 years also had significantly greater nitrogen availability deeper in the soil profile, which suggests that cheatgrass invasion may increase the nitrogen leakiness of the system. This research provides a mechanistic understanding of how invasive weeds impact soils and habitats in the Great Basin. This work will be used by other sientists and land managers that oversee large acreges of rangelands in Nevada, California, Oregon, Idaho and Utah. This research supports the Rangeland, Pastures, and Forage National Program (NP 215) action plan, Research Component 1, Rangeland management systems to enhance the environment and economic viability, and specifically Problem Statement A: Need for economically viable rangeland management practices, germplasm, technologies and strategies to conserve and enhance rangelands ecosystems.
5.Significant Activities that Support Special Target Populations
The saltcedar biological control program includes an experimental release site on the Walker River Paiute Reservation where the saltcedar leaf beetle has established a large population that is defoliating large stands of saltcedar and is dispersing to distant sites. The beetles have dispersed a sufficient distance to be found over the entire reservation and numerous miles in all directions around the reservation.
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. In particular we work closely with farmers in central Nevada on the salt cedar biological control project and on cheatgrass management and revegetation.
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Ashley, M.C., Longland, W.S. 2007. Microsatellite evidence of facultative outcrossing in cheatgrass (Bromus tectorum): Implications for the evolution of invasiveness. Plant Species Biology. 22:197-204.
Rau, B., Chambers, J., Blank, R.R., Johnson, D. 2008. Prescribed Fire, Soil, and Plants: Burn Effects and Interactions in the Central Great Basin. Rangeland Ecology and Management. 61:169-181.
Thorne, R.F., Schoenherr, A.A., Clements, C.D, Young, J.A. 2007. Northern Juniper Woodlands. In: Barbour, M.G., Keeler-Wolf, T., and Schoenherr, A.A., editors. Terrestial Vegetation of California, 3rd Edition. Berkeley, CA: University of California Press. p. 574-586.
Young, J.A., Clements, C.D., Harmon, D.N. 2007. Shieldcress. Rangelands. 29(4):33-37.
Young, J.A., Clements, C.D, Jansen, C.H. 2007. Sagebrush Steppe. In: Barbour, M.G., Keeler-Wolf, T., and Schoenherr, A.A., editors. Terrestial Vegetation of California, 3rd Edition. Berkeley, CA: University of California Press. p. 587-608.
Young, J.A., Clements, C.D. 2007. Cheatgrass and Grazing Rangelands. Rangelands. 29(6):15-20.
Longland, W.S. 2007. Desert rodents reduce seedling recruitment of salsola paulsenii. Western North American Naturalist. 67:378-383.
Blank, R.R. 2008. Biogeochemistry of plant invasion: a case study with bromus tectorum l. Journal of Invasive Plant Science and Management. 1:226-238.
Rau, B.M., Blank, R.R., Chambers, J.C., Johnson, D.W. 2007. Prescribed fire in a Great Basin sagebrush ecosystem: Dynamics of soil extractable nitrogen and phosphorus. Journal of Arid Environments. 71:362-375.