David Pyke

Population biology, fire and restoration ecology of arid and semiarid plants in the Intermountain West and development of protocols to assess ecoysystem status.

Little is known about the basic demographic characteristics of many native species that dominate plant communities in the Intermountain West. In addition, many of these plant communities have deteriorated to such an extent that exotic weedy plants now dominate. My research program focuses on understanding the germination, establishment, survival and reproduction of native plants and of invasive exotic plants.

These basic demographic parameters are measured relative to typical climatic fluctuations and land use practices (e.g., grazing, prescribed and wild fires, herbicide applications). We are currently investigating effectiveness of wildfire rehabilitation projects that are commonly applied on public lands to halt the spread of invasive plants or to stabilize soils. Climate, soil and land use play a major role in success of these efforts, but this has never been examined on a regional level. We hope to develop predictive models to aid management decisions regarding applying these techniques on lands.

The sagebrush steppe exists in a dynamic relationship with fire. However, invasive annual grasses such as cheatgrass, threaten the ecosystem goods and services of this ecosystem by changing fire regimes throughout the region. We study the responses of sagebrush steppe plants after fuel treatments (prescribed fire, mowing, herbicide) to determine if these land uses may cause these ecosystems to cross a threshold that converts them from native plant communities to exotic annual grasslands. We are collaborate with a multi-investigator project called SageSTEP ( www.sagestep.org ) to address these questions.

Status of ecosystems is often difficult to consistently evaluate. Using both qualitative and quantitative indicators of soil stability, hydrologic function and biotic integrity, I am collaborating with other scientists to develop protocols for use by federal agencies to determine status of rangeland ecosystems in the United States.