Fire, Vegetation, and Ecosystem Processes in Yellowstone National Park.

Large scale disturbances such as fire and insect outbreaks are projected to become more frequent and intense in coming decades as a result of climate change. Our current research in Yellowstone examines the interactions between these disturbances and important ecosystem processes. We focus on the following topics: (1) the ways in which past disturbances influence the likelihood and severity of future disturbances (e.g., do severe pine beetle attacks make forest fires more likely?), (2) fire-induced changes in the pathways followed by nitrogen (a key plant nutrient) through different parts of the ecosystem, (3) long-term changes in the species composition, density, and age of tree stands as forests respond to changes in fire frequency, and (4) mathematical models that quantify the effects of different fire regimes on the flow of carbon  

Climate is an important consideration in many of our research efforts. Drought-weakened trees are typically more susceptible to insect attacks, and warmer winters may increase overwinter beetle survival. Fire frequency is also driven primarily by regional climate, and fire-induced changes in soil nitrogen may influence the rate at which trees grow.  

Our team has conducted research in Yellowstone for many years, and we use data from our past work to help predict how the structure and development of Yellowstone's forests will change in the future. Some of our studies have examined projected long-term trends in forest structure that could influence the severity of future climate changes. For example, if more frequent fires lead to a net increase in the amount of carbon released from plant tissue as carbon dioxide, then they may contribute to the increased atmospheric carbon dioxide concentrations responsible for global warming.