Location: Exotic and Invasive Weeds Research
2008 Annual Report
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.
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.
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.