Ranking Forest Effects on Snow Storage: A Decision Tool for Forest Management

Forests modify snow accumulation and ablation rates as well as overall snow storage amounts and durations, with multiple processes acting simultaneously and often in different directions. To synthesize complex forest-snow relations and help guide near-term management decisions, we present a decision tree. The framework is based on a hypothesized hierarchy of processes and associated variables that predict forest effects on snow storage. In locations with high wind speeds, forests enhance snow storage magnitude and duration relative to open areas. Where wind speeds are low, and winter and spring air temperatures are colder, forests diminish snow storage magnitude but enhance duration. Where air temperatures are warmer, forests diminish both snow magnitude and duration. Forest structure and aspect are secondary influences. We apply the decision tree framework to map the influence of forests on snow storage under historic climate conditions across the western United States, but this decision tree is applicable in any region with forests and snow. This framework provides practitioners a first-step evaluation to guide management decisions that consider where and how forests can be managed to optimize in situ water storage alongside other objectives, such as reducing wildfire hazard. This framework also articulates geospatial hypotheses, in order of anticipated importance, to be tested in future investigations of forest-snow-climate relations.

Automated summary

The study presents a decision tree framework based on forest-snow relations, predicting the impact of forests on snow storage based on different combinations of wind speeds and air temperatures. The framework provides a reference for management decisions, optimizing water storage in forests and reducing wildfire hazard.