2013 Annual Report
1a.Objectives (from AD-416):
Determine optimal technique and irrigation protocol for the establishment of native plant species on a site that was formerly used for irrigated agriculture.
1b.Approach (from AD-416):
At Rosaschi Ranch, on the East Walker River, we will use experiments to determine optimal restoration protocols for restoring sagebrush shrublands on formerly irrigated fields. The design will compare levels of irrigation, mulching, and alternative seed mixes, incorporating two levels of functional diversity. Irrigation will be the main plot factor, and the mulching X seeding treatment will be the split plot factor. There will be 5 replications of each treatment combination. Ten separate study plots, 1.5 acres in size, will be established. Five will be irrigated and 5 will serve as controls for the irrigation treatment. Each study plot will be subdivided into seeding/mulching treatments in a split plot design with two levels of mulching (mulch, control) and two levels of seeding (high diversity, low diversity). Soil moisture monitoring will determine the extent of irrigation, which will take place as needed (depending on precipitation patterns) in the early part of each growing season. Research plots will be installed in 2008 and 2009 and irrigated in 2009 and 2010. Data collection will continue through 2012. Density plots will be established at random intervals along transects in each experimental block, and emergence and survival of seeded species will be response variables. Documents Reimbursable with Fish & Wildlife (USFWS). Log 36889. Formerly 5325-11220-005-10R (4/09).
This is the final report for this project which was terminated on September 30, 2013. This agreement was established in support of objective 4 of the in-house project, "Develop restoration methodologies to prevent the invasion of annual grasses (such as cheatgrass, medusahead rye, and/or red brome) following destructive events (such as fire) in rangeland ecosystems".
This project concluded a three-year experimental study at Rosaschi Ranch to determine optimal strategies for re-vegetating abandoned agricultural land and rehabiliting these areas semiarid shrub communities. Collaborators on the project include the United States Department of Interior-Fish and Wildlife Service (USDI FWS), USDA Natural Resources Conservation Service (NRCS), USDA Forest Service Rocky Mountain Research Station (RMRS), USDA Forest Service, and Humboldt-Toiyabe National Forest (Memorandum of Understanding #08-IA-11041701-065). All collaborators attended a meeting in Carson City, Nevada, in October, 2011, where the USDA ARS and Forest Service RMRS presented their preliminary restoration guidelines report. A final meeting was held in Carson City, Nevada, in March of 2012, where all collaborators agreed on a spatially explicit phased restoration plan for the uplands. On April 1, 2012 the USDA ARS and Forest Service RMRS submitted the final restoration plan to all the collaborators. This plan represents the transfer of restoration technology to the Forest Service management unit of the Humboldt-Toiyabe National Forest. In 2013, a manuscript was sent out for review detailing the experimental results. The experimental results were presented at the Ecological Society of America 97th annual meeting in Portland, Oregon, May 5-10, 2012. Restoration of abandoned agricultural lands typically requires seeding or transplanting native species, improving plant-soil-water relations, and controlling invasive species. This study asked if improving water relations via irrigation or surface mulch would result in negative tradeoffs between native species establishment and invasive species competition and if those tradeoffs could be mitigated with herbicide application. The effects of sprinkler irrigation, straw mulch, and herbicide (2, 4-D) on native seed mixtures planted in two consecutive years in an abandoned agricultural field in southwestern Nevada, USA were examined. Shrubs, grasses and forbs were seeded, but this study found low success of shrubs and forbs and the seeding density of selected grass species should be high to facilitate revegetation success. Precipitation was low during the first growing season and seeded plant density, cover or biomass increased in response to irrigation. Precipitation was relatively high during the second growing season, seeded plant densities and biomass were generally high, and irrigation had inconsistent effects. Mulch increased seeded plant establishment without irrigation during the dry year. Invasive plant biomass and cover also were influenced by growing season, but irrigation increased invasive plants regardless of precipitation. Herbicide application had no effect, likely due to differences in invasive species phenology. Positive effects of irrigation on seeded plant density, cover, and biomass outweighed negative tradeoffs of increases in invasive plants, but in ecosystems with highly variable precipitation, restoration strategies should be adaptive.