Wildfire, drought, and insects are reshaping forests in the Western United States in a manner that is being exacerbated by warming temperatures. Disturbance events such as these can significantly alter the amount of land that is covered by forest in an area or region. Consequently, changes in forest cover from disturbance can impact water runoff conditions leading to dangerous flooding, erosion, and water quality issues. These events can be costly for society. In response, many land managers are using forest thinning and prescribed burning practices to reduce disturbance impacts, especially those that are caused by high-severity wildfire. In contrast to the wealth of research on the advantages of forest thinning for reducing high-severity [...]
Summary
Wildfire, drought, and insects are reshaping forests in the Western United States in a manner that is being exacerbated by warming temperatures. Disturbance events such as these can significantly alter the amount of land that is covered by forest in an area or region. Consequently, changes in forest cover from disturbance can impact water runoff conditions leading to dangerous flooding, erosion, and water quality issues. These events can be costly for society. In response, many land managers are using forest thinning and prescribed burning practices to reduce disturbance impacts, especially those that are caused by high-severity wildfire. In contrast to the wealth of research on the advantages of forest thinning for reducing high-severity fires and their immediate impacts, much less is known about the long-term implications of these changes on forest function. Current research has only a limited understanding of how forest structure alters snow accumulation and melt, and in turn, how these snow dynamics feed back into forest structure to influence ecosystem function. Quantifying the relationships between forest structural heterogeneity (i.e. differences in tree size and distribution), snowpack development, and snowpack persistence (i.e. the length of time snow remains on the ground) are key for understanding the potential for forest management to influence water availability and safeguard future forest ecosystems.
The proposed work seeks to answer the following research questions: 1) How do wildfire and forest management practices which reduce high-severity fire risk influence snow accumulation, persistence, and forest function? 2) How will these impacts vary through time under warmer and dryer conditions that are projected for the Southwestern United States?
To answer these questions, the research team will measure snowpack dynamics and ecosystem function in forests that have experienced wildfire, been subject to forest thinning, and those that have been left undisturbed. This information will be used to determine what type of forest canopy structure not only reduces the risk of large wildfires, but also increases the function of the forest ecosystem. Model simulations will help to determine the impact of various scenarios in the face of a changing climate. Results of this work will develop best practices and management tools for forest managers. These findings can be incorporated into future strategies aimed at reducing tree competition for water under higher temperatures.