Mapping Mixed Mountain Shrub Communities to Support WLCI Conservation Planning and Effectiveness Monitoring of Habitat Treatments
Photo of mule deer standing on crest of hill in mixed mountain shrub habitat.

Mule deer in mountain shrub habitat. Mixed mountain shrub communities are critical habitat for mule deer in the WLCI region.

Project Partners

Wyoming Game and Fish Department

National Park Service

Bureau of Land Management

U.S. Fish and Wildlife Service

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Why are Mixed Mountain Shrublands Important to the WLCI?

The mixed mountain shrub community is one of five priority habitat types identified by WLCI partners that provide crucial habitat for focal wildlife species. Information on the condition and distribution of priority habitats and of wildlife populations that rely on these habitats are needed to inform resource planning. The current extent and condition of mixed mountain shrub patches is unknown in most of the WLCI region; thus, trends in their condition and mechanisms driving those conditions are also unknown. Mapping efforts, which began in 2012, include currant, gooseberry, and sumac species, “true” mountain mahogany and curl-leaf mountain mahogany, chokecherry, antelope bitterbrush, and snowberry. WLCI habitat conservation projects aim to preserve or improve condition in these priority habitats.

How Can Better Maps of Mixed Mountain Shrublands Help With Conservation Planning?

Maps and other information from this work help to support WLCI partners with conservation planning and effectiveness monitoring of habitat treatments. Treatments in mixed mountain shrublands are designed to enhance crucial winter and transition habitat for mule deer and include mowing, aeration, seeding, burning, and herbicide applications. The USGS continues to improve its approaches to mapping and modeling vegetation to support our ongoing mountain shrub and mule deer research.

Findings to Date

  • Monitoring data from selected stands indicate an overall decline in mixed mountain shrub communities.
  • Hypothesized causes of decline range from persistent drought to herbivory and, possibly, factors associated with increased energy resource development.

Study Objectives

  • Map and measure the distribution and current condition of mixed mountain shrub communities.
  • Evaluate potential effects of habitat treatments, weather-related trends, increased energy resource development, and other change agents.
  • Ground truth existing vegetation within the mixed mountain shrub study area.
  • Use statistics, digitization, modified knowledge-based classification, and other approaches for mapping vegetation within the study area.
  • Present map products to cooperators and provide support for using the maps in their decision-making.
  • Iteratively ground truth map products to improve them and use them to design a monitoring system.

Mixed mountain shrub patches that have been mapped in the Big Piney–La Barge area of Wyoming. Click to enlarge.

How Were Mixed Mountain Shrub Communities Mapped?

USGS scientists recorded the presence of mixed mountain shrub communities in the Big Piney-La Barge Area identified in the Wyoming Range Mule Deer Habitat Plan. We selected this area to take advantage of existing assessment and monitoring data acquired by WLCI partners. To map mountain shrub patches in the field, we used two methods─either the patch boundaries were walked while marking the patch polygon with a global positioning system (GPS) unit, or patches were hand drawn on topographic maps while attributing an associated GPS point with photographic documentation. We estimated shrub density and browse intensity for each shrub patch. Using field and remotely sensed satellite imagery, we built models of site (habitat) suitability for mountain shrub occurrence to test our ability to expand our mapped area. We assessed shrub community condition of mountain mahogany in 45 locations randomly selected from transitional and crucial mule deer winter range stratified by distance from well pads. We measured herbivory of mountain mahogany leaders in early spring and developed and implemented a protocol to evaluate mountain mahogany establishment dates, growth and to reconstruct browsing histories. We quantified shrub foliar cover, density, herbivory, mortality, and age and size class structure.

Photo of small shrub and measuring stick.
Photo of mountain mahogany beside book for comparison.
Photo of researcher taking measurements in mixed mountain shrub habitat.

We measured the height and other shrub characteristics in order to assess the health, structure, and species composition of mixed mountain shrub patches across the landscape. Baseline data can provide a benchmark for later comparisons.

Intensively browsed mountain mahogany near La Barge, Wyo. Measuring and monitoring browsing in mixed mountain shrub communities will provide information on the effects of ungulate herbivory on these communities.

Researchers assessed shrub community condition of mountain mahogany in 45 locations throughout the Big Piney-La Barge area of Wyoming.