Location: Watershed Management Research2012 Annual Report
1a. Objectives (from AD-416):
The overall objective of this research project is to improve scientific understanding to transfer technology related to assessing and mitigating the impacts of ecological disturbances by invasion-weeds,fire and predation on rangeland water, vegetation and animal resources within sagebrush ecosystems of the Intermountain West. The aim is to provide sound science-base information and management tools in support of private and public land management activities. Specific research objectives inclued: 1) Develop strategic management tools and guidelines for use in fire impact assessment and rehabilitation planning of sagebrush ecosystems of the Intermountain West to aid land managers in determining the location, severity and persistence of fire impacts on post-fire runoff/erosion. 2) Improve guidelines and methods for monitoring and assessing impacts of juniper encroachment and management on plant, soil and water resources in sagebrush-steppe ecosystems to enhance efficiency and success in action agency planning and implementation of juniper-control treatments throughout the Intermountain West: 3) Develop methodology for classifying seedbed microclimate and identify microclimatic thresholds for successful germination and early establishment of seeded grass species in sagebrush-steppe ecosystems to improve success of rangeland restoration efforts across the Intermountain West: 4)Evaluate the effects of landscape-scale disturbance such as fire, invasive plants, and predation on livestock productivity and livestock use of stream systems and other critical resouces of sagebrush-steppe ecosystems throughout the Intermountain West so producers and land managers can employ adaptive management and better plan for changes in animal resources use and productivity.
1b. Approach (from AD-416):
A suite of hydrology, vegetation, remote sensing and animal behavior experiments will be conducted from point to landscape scales to improve scientific understanding and produce technology for managing impacts of ecological disturbances by fire,invasive-weed and predation within sagebrush ecosystems of the Intermountain West. This research project will deliver products to aid land managers in conducting fire impact risk assessments, inventory and assessing the impacts of juniper encroachment, planning and implementing juniper-control treatments, determining seedbed-microclimatic requirements for establishment of native and introduced rangeland-grass species appropriate plant species and optimal planting time for post-fire rangeland rehabilitation and restoration treatments, evaluating livestock behavioral response and resource use following disturbance and establish appropriate post-fire livestock grazing strategies. Outcomes of this project help to assesss and quantify environmental benefits of conservation practices and improve action agency land use planning and management activities. Resultant benefits include potential savings of millions of dollars in wildfire mitigation,improve water quality by reducing sediment delivery to streams, reduced loss of forage for livestock and wildlife from juniper and cheatgrass invaion, improved species diversity and wildlife habitat, and greater livestock productivity from rangeland systems.
3. Progress Report:
A framework was developed for describing post-fire runoff and erosion as a function of fire-induced changes in site characteristics (i.e. ground cover, soil water repellency, aggregate stability, surface roughness) that defines site susceptibility to runoff and erosion events. The overall post-fire hydrologic vulnerability of a site can then be considered in a probabilistic framework that predicts hydrologic response for a range of potential storms and site susceptibilities. An examination of the ecohydrologic impacts of juniper encroachment into sagebrush-steppe showed that woody plant encroachment into water-limited rangelands can induce a shift from biotic (plant)-controlled resource retention to abiotic (runoff)-driven losses of critical soil resources. The biotic-to-abiotic shift occurs when bare ground exceeds 50-60% propagating connectivity of runoff and erosion processes, that in-turn, promote ecohydrologic resilience of the post-encroachment community. New concentrated flow algorithms and parameter estimation equations were developed and implemented in the Rangeland Hydrology and Erosion Model (RHEM). Meteorological inputs and hydrologic outputs at the 4 South Mountain Juniper Hydrology Project watersheds were monitored for a sixth year to establish pre-treatment hydrologic response. A 4th year of monitoring prescribed fire, herbicide, seeding rate treatments at the Warm Springs study site in the Boise Foothills was completed and field sites were established at 5 locations in southern Idaho to study interactive effects of soil temperature, water availability and weed competition on early germination, emergence and seedling development of perennial bunchgrass species. Restoration-specific guidelines were synthesized for using weather data in rangeland restoration planning and a proposed framework was developed for weather-centric adaptive management. The framework includes analysis of site-specific historical weather data, evaluation and ranking of annual, seasonal and monthly precipitation and temperature patterns, and assessment of seedbed microclimatic conditions relative to phenological life stages of seeded plant materials. Extensive GPS collar location data were used to evaluate beef cattle activity budgets and movement path characteristic responses to prescribed fire treatments. Results indicate that fire can significantly alter cattle behavior for 2 to 3 years following burning. However, results are also dependent on the time of year grazing takes place. Sixteen cows were fitted with Clark GPS collars at the Copper Basin, Idaho study area to continue evaluation of cattle resource-selection and activity budge responses to gray wolf presence. These 5-min interval data sets provide unique temporally-intensive animal location information throughout large rangeland grazing allotments over long time periods. These data contain both acute, short-term effects (e.g., bunching and flight events) and chronic, longer-term effects (e.g., altered foraging patterns and riparian occupation durations) of wolf presence on cattle distribution patterns.
1. Expanded rangeland erosion model for disturbed conditions. Resource managers have long-needed erosion estimates on rangelands for many purposes, including development of land management plans, evaluation of the environmental benefits of applying resource conservation practices, and planning erosion control efforts following disturbances like wildfire, just to name a few. The Rangeland Hydrology and Erosion Model (RHEM) developed by ARS is the first erosion model specifically designed for use on rangelands in the United States. Using extensive field measurements from across the Great Basin, ARS scientists in Boise, Idaho, have expanded the applicability of the RHEM model to include disturbed rangeland conditions that have a very high erosion potential. RHEM can now be run by land managers on the web (http://dss.tucson.ars.ag.gov/rhem/) using readily available soil and vegetation data to estimate rates of runoff and erosion under disturbed soils conditions found after fire or dramatic change in vegetation such as shrub and woodland invasion.
2. Online weather-centric recommendations for planning restoration of rangeland vegetation. The weather across most western rangelands is highly variable and often has a big impact on the success or failure of most rangeland restoration efforts. ARS scientists in Boise, Idaho, created a microclimatic index of favorable seedbed conditions, and synthesized a management framework for using historical weather data in an adaptive management context for planning and managing restoration efforts on rangelands. This framework includes analysis of site-specific historical weather data, evaluation and ranking of annual, seasonal and monthly precipitation and temperature patterns, and assessment of seedbed microclimatic conditions relative to the growth stage of seeded plant materials. Available via the web (http://www.ebipm.org/) or used as a spreadsheet template, implementation of weather-centric restoration planning will improve the success of fire-rehabilitation and restoration projects across western rangelands, and provide land managers a mechanism to adapt restoration efforts to fit site-specific weather conditions.
3. Impacts of herding sheep across mountain streams. The impacts on water quality when bands of domestic sheep are tightly-herded across rangeland streams are largely unknown. ARS scientists in Boise, Idaho, evaluated suspended sediment and Escherichia coli bacteria levels before, during, and after crossings made by ewe-lamb bands (2,000 – 2,500 individuals) on high-elevation stream systems in eastern Idaho and southwestern Montana. Although crossings induced brief intense elevations in both pollutants, these effects attenuated rapidly with downstream distance and were unlikely to cause permanent or long-lasting impacts to stream water quality. This information will help domestic sheep producers and natural resource managers develop and implement appropriate sheep grazing management plans for high-elevation rangelands.
Al-Hamdan, O.Z., Pierson Jr, F.B., Nearing, M.A., Williams, C.J., Stone, J.J., Kormos, P.R., Boll, J., Weltz, M.A. 2012. Concentrated flow erodibility for physically-based erosion models: temporal variability in disturbed and undisturbed rangelands. Water Resources Research. DOI: 10.1029/2011WR011464.