Research Programs and Projects at this Location : USDA ARS

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Research Project: Assessment and Mitigation of Disturbed Sagebrush-Steppe Ecosystems

Location: Northwest Watershed Research Center

2021 Annual Report

Objectives
1) As part of the Long-Term Agroecosystems Research (LTAR) network, and in concert with similar long-term, land-based research infrastructure in the U.S., use the Great Basin LTAR site to improve the observational capabilities and data accessibility of the LTAR network and support research to sustain or enhance agricultural production and environmental quality in agroecosystems characteristic of the Great Basin. Research and data collection are planned and implemented based on the LTAR site application and in accordance with the responsibilities outlined in the LTAR Shared Research Strategy (LTARN, 2015), a living document that serves as a roadmap for LTAR implementation. Participation in the LTAR network includes research and data management in support of the ARS GRACEnet and/or Livestock GRACEnet projects. 1A) Improve the understanding of Great Basin ecosystem function and processes by collecting, analyzing and curating multi-scale data in support of LTAR and national database development efforts. 1B) Develop and evaluate remote-sensing tools and approaches for quantifying fine-scale vegetation and wildland fuel dynamics. 1C) Contribute and utilize weather and climate tool applications through the LTAR Climate Group for national and regional LTAR agricultural and natural resource modeling programs in grazing management, ecosystem monitoring, remote sensing, soil productivity, hydrology and erosion. 1D) Create a framework of dominant socioeconomic metrics for assessing long-term sustainability of livestock production and ecosystem services relevant to rural communities dependent upon Great Basin rangelands. 2) Evaluate the interacting effects of livestock grazing, fire, and invasive plants on rangeland ecosystems through development, testing, and application of new databases, assessment tools, and management strategies. 2A) Determine if strategically targeted cattle grazing is effective for reducing fine fuels, moderating wildfire behavior, providing better initial attack alternatives for wildland fire fighters, and protecting critical resources from wildfire damage. 2B) Assess the efficacy of prescriptive cattle grazing for rehabilitating and/or restoring degraded sagebrush-steppe rangelands currently dominated by invasive annual grasses. 2C) Evaluate impacts of the interaction of fire and annual grass invasion on hillslope ecohydrologic processes. 3) Develop weather, climate and eco-hydrologic tools for agricultural and natural resource management applications. 3A) Evaluate, develop and implement soil, plant and atmospheric modeling tools for evaluating and optimizing planting date effects on seedling establishment success of rangeland restoration plant materials. 3B) Evaluate, develop and implement landscape-scale applications for weather centric rangeland restoration planning and management. 3C) Enhance the applicability of the Rangeland Hydrology and Erosion Model (RHEM) for assessing ecohydrologic impacts of annual grass invasion and altered fire regimes.

Approach
Goal 1A: Improve infrastructure, data acquisition protocols, and database management at the Great Basin LTAR. Install phenology cameras and extend vegetation monitoring of replicated sites in three Great Basin (GB) ecosystems. Hypothesis 1B: Unmanned aircraft systems (UAS) will be effective for quantifying vegetation dynamics and fire severity. We will test efficacy of high-resolution imagery, Structure-from-Motion (SfM), and other UAS-derived products for estimating biomass, cover, fuel continuity, and fire severity in the three GB ecosystems. Goal 1C: Develop methodology for utilizing gridded weather data for agro-ecosystem modeling and risk-assessment applications. The weather/climate toolbox will be expanded to provide forecasting data for the entire U.S. to support the LTAR network and broad research efforts. Goal 1D: Develop a socio-economic framework for assessing barriers to adoption of livestock grazing systems in cheatgrass rangelands. Scoping interviews, surveys, and participatory workshops will be used to assess stakeholder and community perceptions of rangeland issues and changes in those perceptions over time. Hypothesis 2A: Targeted grazing can create fuel breaks which moderate wildfire behavior without impacting ecosystem health. We will apply intensive grazing to cheatgrass rangeland, monitor herbaceous fuel height/load reduction to targeted level, and assess ecosystem response to treatment using augmented indicators and protocols developed for the BLM Assessment, Inventory, and Monitoring (AIM) program. Hypothesis 2B: Prescriptive grazing will promote recovery of desirable plant species within degraded rangelands. We will apply replicates of a combination of spring and dormant season grazing to impact cheatgrass cohorts and monitor ecosystem response using AIM indicators and protocols. Hypothesis 2C: Cheatgrass invasion and associated altered fire regimes will increase runoff and erosion. Runoff and erosion will be assessed in unburned and burned cheatgrass compared to unburned sagebrush-steppe (control) using rainfall and overland-flow field simulators. Hypothesis 3A: Hydrothermal germination response models and weather datasets can characterize seed germination, post-germination mortality, and seedling emergence rates. The SHAW model using historical weather data from gridMet will be used to parameterize hydrothermal germination models to evaluate species sensitivity to planting date, over-wintering conditions, and topo-edaphic conditions. Goal 3B: Develop tools for incorporating weather, climate and microclimatic variability into restoration planning and management. We will enhance existing web-application to provide daily weather parameters and parameterize the SHAW model with SSURGO soils data to thus facilitate modeling of germination success and seedling survival under various climatic and environmental scenarios. Goal 3C: Expand the capabilities of RHEM for conducting hydrologic risk assessment on disturbed rangelands. Develop RHEM equations for cheatgrass systems, test the utility of the enhanced RHEM, and establish guidelines for use of RHEM in combination with soil burn severity mapping for risk assessments.

Progress Report
In support of Objective 1, researchers at Boise, Idaho, maintained existing phenology cameras (Phenocam) located at Nancy Gulch, and Reynolds Mountain, and also installed an additional camera at Lower Sheep Creek located on the Reynolds Creek Experimental Watershed (RCEW) near Murphy, Idaho. All three automated cameras successfully contributed imagery to the nation-wide Long-Term Agroecosystem Research (LTAR) and Phenocam networks. Data collections for the RCEW Long-Term Vegetation Research program and the Great Basin LTAR site were completed as planned. Also, replicate sets of 15 Modified Wilson and Cooke (MWAC) wind erosion samplers were installed in vegetation enclosures at the Nancy Gulch (Wyoming big sagebrush), Lower Sheep (low sagebrush), and Reynolds Mountain (mountain big sagebrush) study sites and periodically monitored for one year. Initial analysis of collected sediments identified potential influences of nearby two-track roads. The roads at Nancy Gulch and Lower Sheep have now been closed-off, and a new site for Reynolds Mountain will be identified for future instrumentation. This network of wind erosion monitoring sites traverses large elevation and precipitation gradients and will provide important baseline estimates of the horizontal sediment mass flux for regional sagebrush ecosystems and data for comparison across LTAR network sites. ARS researchers in Boise, Idaho, have continued collecting imagery from Unmanned Aircraft Systems (UAS) and corresponding field data from three core research areas at RCEW (Nancy Gulch, Lower Sheep Creek, and Reynolds Mountain). A draft manuscript comparing the accuracies of UAS-derived vegetation indices (e.g., Modified Soil-Adjusted Vegetation Index (MSAVI)) for predicting fractional cover of plant functional types was developed and reviewed as part of a collaboration with Boise State University (2052-13610-014-10A, "Developing Remote Sensing Tools for Rangeland Vegetation Inventory and Assessment"). A topic modeling framework for cross-scale analysis of plant community composition was published. Results from a global study using Structure-from-Motion (SfM) techniques to develop robust relationships between vegetation biomass and SfM-derived plant height were published. Collaborative efforts continued with the University of Idaho (2052-13610-014-12S, "Socio-economic Assessment of Great Basin Livestock Production Systems”) and stakeholders in the Northern Great Basin. Audio-recorded interviews with stakeholders, originally acquired in 2020, were transcribed, and qualitative analysis was conducted so themes and patterns could be identified regarding: i) how livestock producers perceive and adapt to land cover and community change; ii) how socio-economic stressors on livestock production intersect with problems and opportunities presented by changes in annual grass cover, wildfire threat, and rural community structure; and iii) how producers perceive social-ecological impacts to their livelihoods, rural communities, and rangeland resources over time. A manuscript tentatively entitled, “Social-ecological impacts of invasive annual grass cover and rural community change over time in the northern Great Basin,” is under development. Collaboration with University of Idaho social scientists produced an insights paper entitled, “Communal processes of health and well-being for rangelands research and practice,” which has been provisionally accepted for a special issue on Social Science Advancements for Well-Being in Rangelands Research in the journal, Rangelands. This research lays the groundwork for broadening the geographic scope of stakeholder engagement for the Great Basin site within the USDA LTAR network. In support of Objective 2, the Multi-Regional Targeted Grazing (TG) Experiment continued as a collaboration between ARS researchers at Boise, Idaho, and the U.S. Department of the Interior (USDI) Bureau of Land Management (BLM) to evaluate the efficacy of targeted cattle grazing for creating and maintaining fuel breaks on fire-prone landscapes. Data collections for assessing TG treatment attainment and ecosystem response were completed as planned at all three existing project areas in Boise, Idaho, Elko, Nevada, and Frenchglen, Oregon. Summarizations of these TG data were provided to the BLM National Office in fulfillment of the Interagency Agreement (2052-13610-014-08I, "BLM/ARS Targeted Grazing Demonstration Monitoring Project"). Data collections for ecosystem responses under the Great Basin LTAR Common Experiment (CE), contrasting High Intensity Long Frequency (HILF) cattle grazing to nominal BLM permitted grazing, were collected as planned. Summarizations of these CE data were provided to the BLM Boise District, Snake River Birds of Prey National Conservation Area, and Four Rivers Field offices and the cattle producers who are the principal project collaborators. Additionally, in 2019, initial study sites, experimental design, and methods were identified for a field study of ecohydrology impacts of cheatgrass invasion and fire. Collection of field data for this study was to begin in the spring of 2020, but mandatory COVID protocols made field data collection impossible in 2020 and again in 2021. As a contingency, work has proceeded using extensive field data collected in the past by ARS scientists at Boise, Idaho, on juniper invasion and fire impacts to examine the long-term effectiveness of mechanical tree removal and prescribed fire to re-establish sagebrush steppe vegetation and associated spatial patterns in surface runoff and erosion. A manuscript summarizing the results of the hydrologic component of the 15-year Sagebrush Steppe Treatment Evaluation Project (SageSTEP) study was published. In addition, ARS scientists at Boise, Idaho, and Las Cruces, New Mexico, initiated work to enter the extensive SageSTEP study database into the Landscape Data Commons, hosted by ARS Las Cruces, thereby making these data available to all rangeland managers in Natural Resources Conservation Service (NRCS) and BLM. In support of Objective 3, ARS scientists at Boise, Idaho, in collaboration with ARS scientists at Burns, Oregon, Woodward, Oklahoma, and Fort Collins, Colorado, and collaborators at Boise State University and the University of California, evaluated elevation effects on seedbed favorability for native grass germination and emergence in the Boise Front Management Area. ARS researchers determined that elevation and slope effects on seedbed microclimate during the establishment season are highly correlated with ecological resistance and resilience metrics that are used to prioritize native plant restoration areas on federal land. These mechanistic metrics for seedbed favorability could potentially be used to expand existing resistance and resilience tools to also apply to individual year restoration outcomes and to derive weather-centric restoration tools to take advantage of spatial weather variability that may occur in any given year. Additionally, ARS scientists at Boise, Idaho, collaborated with the BLM and the Society for Ecological Restoration to develop online educational modules for training BLM and other public and private-land restoration specialists in seed technology and tools for use in arid-land restoration. Researchers at ARS Boise contributed weather-centric restoration concepts and tools to several online restoration training modules including: i) Weather-related challenges to working in arid and semi-arid lands; ii) Weather resources for restoration planning and characterization of site conditions; iii) Weather and climate influences on site reference conditions; iv) The effect of weather variability on restoration outcomes; and v) Weather considerations in the development of monitoring and adaptive management plans. Inclusion of weather-centric planning and evaluation tools could significantly improve the efficiency of restoration programs as weather variability is one of the principal determinants of rangeland restoration success in both the short and long term. Also, parameter estimation equations for the Rangeland Hydrology and Erosion Model (RHEM) effective hydraulic conductivity (Ke) under burned rangeland conditions have been developed from extensive past rainfall simulation studies conducted by ARS scientists at Boise, Idaho. This effort to develop parameterization equations for RHEM was expanded to include developing rangeland parameterization equations for the ARS-developed, Water Erosion Prediction Project (WEPP) model and its derivatives such as the Erosion Risk Management Tool (ERMiT) developed by ARS scientists at Boise, Idaho, in collaboration with the Forest Service, Rocky Mountain Research Station. A manuscript defining rangeland infiltration, interrill, and rill erodibility parameterization equations for the WEPP model consistent with parameterization equations developed for RHEM has been submitted for publication. The paper also provides updated distributions of input parameters for ERMiT. ARS scientists at Boise, Idaho, and Las Cruces, New Mexico, established protocols for estimating all RHEM parameters from vegetation and soils information routinely collected under the NRCS’ National Resource Inventory (NRI) and the BLM’s Assessment, Inventory, and Monitoring (AIM) programs. These estimated RHEM parameters will soon be available through the Landscape Data Commons hosted by ARS in Las Cruces, New Mexico.

Accomplishments
1. Sustainable livelihoods from global drylands require pastoralists mobility. Drylands occupy 41% of the global land surface, contain nearly one-third of the world’s biodiversity hotspots, and deliver over $1 trillion in ecosystem goods and services to more than 38% of the global human population. Pastoralism is the most common form of agriculture on drylands but is also among the most threatened of human livelihoods. ARS researchers at Boise, Idaho, evaluated the role herd mobility plays in promoting sustainable pastoralism on drylands such as the Mongolian steppes, East African savannas, and diverse rangelands of the western United States. Pastoral strategies with high degrees of herd movement and enterprise flexibility, previously common in traditional pastoralism, tended to be more socio-economically and environmentally sustainable than strategies with reduced mobility, rigid policy constraints, and aid-dependent risk management. Despite on-going global trends toward less open space and increased land use demands, both greater herd mobility and policy flexibility emerged from this research as critical requirements for sustainable pastoral livelihoods important for successful achievement of the United Nations Sustainable Development Goals for Zero Hunger (#1) and Life on the Land (#15).

2. Improving rangeland restoration success in complex terrain. Rangelands are undergoing type conversion to introduced annual weeds over millions of hectares of public and private rangeland in the Intermountain Western United States. The ecological resistance and resilience of native plant communities, however, seems to depend upon topographic patterns associated with slope, aspect and elevation. ARS researchers in Boise, Idaho, Burns, Oregon, Fort Collins, Colorado, and Woodward, Oklahoma, and collaborators at Boise State University and the University of California, have modeled seedbed soil and water relations in the 17,000-hectare Boise Front Management Area and identified patterns of seasonal soil microclimate that are similar to these spatial patterns of invasive weed distribution. These microclimatic models can directly improve the accuracy of resistance and resilience maps which are currently being used to prioritize restoration activities on more resilient federal lands. These tools may also provide new metrics for improving the ability to re-establish desirable native plants on lower elevation and southern slopes that are currently the most vulnerable to wildfire and weed disturbance. These modeling tools are currently being used as part of the annual Bureau of Land Management rangeland restoration training course and are being used by Federal and State agency land managers and university collaborators as part of their regional research programs to improve restoration outcomes on western rangelands.

3. Targeted cattle grazing prevents megafires. Rangeland megafires (>100,000 ac) which threaten human life, property, and critical natural resources are increasingly common in the western United States and account for much of the 1-3 billion in federal tax-payer dollars spent annually on wildfire suppression. Targeted livestock grazing potentially offers an efficient and effective means of reducing wildfire size and damage by creating fuel breaks strategically positioned between fire-prone landscapes (e.g., those dominated by highly-flammable, invasive annual grasses like cheatgrass) and critically threatened resources like wildland-urban interface or habitat for greater sage-grouse and other wildlife species of concern. ARS Researchers at Boise, Idaho, in collaboration with the Bureau of Land Management, evaluated the efficacy of targeted cattle grazing for fuel breaks at sites distributed across the Great Basin region in Idaho, Nevada, and Oregon. Intensive but carefully managed cattle grazing reduced fuel height, loading, and connectivity while avoiding adverse impact to environment health within the fuel break areas. These fuel reductions effectively moderate fire behavior as demonstrated in three wildfires (Boulder Creek 2018, Beowawe 2020, and Welch Creek 2021) occurring at the Nevada site where targeted grazing fuel breaks reduced fire intensity and rate of spread, allowing firefighters to make more timely arrivals and apply better initial attack options to contain the fires to smaller acreages (1,029, 54, and 41 acres, respectively) than without fuel breaks. Additional validation continues, but it is increasingly clear that targeted grazing provides a unique opportunity for agricultural producers, private landowners, and public land managers to strategically reduce fine fuels and wildfire size and severity with a tool (livestock) that is already in place on all rangelands regardless of ownership and at a scope commensurate with the annual grass-wildfire problem.

U.S. DEPARTMENT OF AGRICULTURE

Northwest Watershed Research Center: Boise, ID