Location: Watershed Management Research2011 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 to improve scientific understanding and produce technology for managing impacts of ecological disturbances by fire, invasive-weeds, 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; 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 establishing appropriate post-fire livestock grazing strategies. Outcomes of this project help to assess and quantify environmental benefits of conservation practices and improve agency land use planning and management activities. Resultant benefits include potential savings of millions of dollars in wildfire mitigation, improved water quality by reducing sediment delivery to streams, reduced loss of forage for livestock and wildlife from juniper and cheatgrass invasion, improved species diversity and wildlife habitat, and greater livestock productivity from rangeland systems.
3. Progress Report
Extensive data from numerous field experiments of the impact of fire and juniper encroachment on runoff and erosion from across the Great Basin were used to derive estimates and develop predictive equations for concentrated flow velocity, flow width, and hydraulic friction factors for the Rangeland Hydrology and Erosion Model (RHEM). The derived parameter estimation equations have now been implemented in RHEM and are ready for independent testing. Work is now underway to estimate and predict dynamic maximum soil erodibility parameters for disturbed conditions such as fire and juniper encroachment. Once completed, this work will expand the applicability of RHEM to disturbed rangeland conditions. A 3rd year monitoring of a 4 year experiment was completed in the Boise foothills to investigate prescribed fire, herbicide rate, seeding rate, and species effects on rangeland restoration sagebrush/bunchgrass rangeland that has been taken over by Medusahead wildrye. The first and second year results confirm large impacts of fall-applied herbicide and fire on weed composition and density during the spring establishment period. ARS researchers at the Northwest Watershed Research Center (NWRC) in Boise, Idaho, also began monitoring three research and demonstration areas in the Snake River Plain Birds of Prey National Conservation Area for development of a cooperative Environmental Assessment for joint ARS/Bureau of Land Management restoration. Development of the hardware version 2.1.1 and software version 2.0 of the Clark Global Positioning System (GPS) tracking collars was completed thus reducing the footprint of the electronics through the use of microSD memory cards, surface-mounted GPS modules, and a reduced part count. Improved data compilation and quality evaluation functionalities were added to the KRESS Modeler software (http//www.kress.us/index.htm) to allow more rapid preparation and error screening of the huge volumes of data produced by the GPS collars on livestock. GPS collar location data acquired during 2001-2009 were analyzed using resource-selection functions based on negative-binomial regressions to evaluate beef cattle behavioral response to prescribed fire treatments. Results indicate that fire can significantly alter cattle behavior and use patterns for 2 to 3 years following burning. However, results are also dependent on the time of year grazing takes place. Fifteen, mature, lactating beef 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 level. These 5-min interval data sets are unique in that they represent the combination of temporally-intensive animal location sampling throughout large rangeland grazing allotments over long time periods. These data sets contain both acute, short-term effects (e.g., bunching and flight events) as well as the chronic, longer-term effects (e.g., altered foraging patterns and riparian occupation durations) of wolf presence on cattle distribution patterns.
1. Hydrologic vulnerability of sagebrush steppe following pinyon and juniper encroachment. Woodland encroachment on western rangelands has altered the vegetative structure and hydrologic function of large expanses of historic shrub steppe. ARS researchers at the Northwest Watershed Research Center in Boise, Idaho, conducted rainfall simulation and concentrated-flow experiments that measured infiltration, runoff, and erosion in these encroaching plant communities. Small (0.5 m2) and large (13 m2) plot scales were used to document relative hydrologic stability of areas underneath tree canopies. Shrub-interspaces between trees exhibited higher water and soil loss vulnerability as tree density increased. As tree density increases, understory vegetation decreases and when ground cover falls below 40-50%, runoff and erosion dramatically increases. These results provide a basis for land managers to better assess and predict Great Basin sagebrush steppe hydrologic and erosional responses to woodland encroachment.
2. Characterizing western juniper expansion via a fusion of LandSat 5 thematic mapper and Light Detection and Ranging (LiDAR) data. Western juniper now dominates over 8 million acres of rangeland in the western United States. Over 95% of existing trees have expanded beyond their historical habitat and invaded adjacent sagebrush-bunchgrass rangeland. There is a critical need to develop remote sensing tools to assess the distribution of this invasive species in order for management agencies to assign treatment priorities for allocation of rangeland restoration funds. ARS researchers at the Northwest Watershed Research Center in Boise, Idaho, developed a methodology to fuse LandSat and LiDAR remote sensing data to classify juniper invasion status and trajectory. This technique was demonstrated to have relatively high accuracy and was used to evaluate juniper invasion at the ARS Reynolds Creek Experimental Watershed. This improved technology can be used by land management agencies for rapid monitoring, assessment, and identification of priority areas for juniper control treatments that will restore historical plant communities and enhance rangeland productivity.
Pierson Jr, F.B., Williams, C.J., Kormos, P.R., Hardegree, S.P., Clark, P., Rau, B.M. 2010. Hydrologic vulnerability of sagebrush steppe following pinyon and juniper encroachment. Rangeland Ecology and Management. 63(6):614-629.