Abstract
In response to increased wildfires across the United States, the U.S. Forest Service (Forest Service) must have the necessary tools to make defendable, consistent, and effective
management decisions. Wildfire activity has increased due to heavy fuel loads, drier
climates, and longer growing seasons. This research investigates the Forest Service's legal
challenges while adapting management practices and understanding what tools might help
improve decision-making.
High-intensity wildfires can burn a vast amount (>75%) of forest canopies and consume live
and dead vegetation on the forest floor. The volatilization of organic matter can significantly
alter soil characteristics, creating conditions that can increase surface erosion and debris
flows and cause landslides. These processes can affect downstream sedimentation and affect
water quality. Management decisions about whether to enter these landscapes and what the
impacts are have been informed by research dedicated to studying impacts from activities
like post-fire salvage logging. Post-fire salvage logging aims to recover the economic loss
from a catastrophic wildfire. Ground-based logging activities have been shown to increase
erosion risk, and considerations must be made to minimize logging effects on erosion risk
because of legal requirements necessitating environmental review.
In response to the need to estimate erosion and attempts to minimize negative impacts in
forest environments, the Forest Service has developed the Forest Service-Water Erosion
Prediction Project (FS-WEPP) suite of tools for use in forest landscapes including post-fire
forest environments. The WEPP model has been heavily validated in agricultural and
rangeland settings and is increasingly validated in disturbed forest environments, including
mechanical salvage logging in post-fire settings. This study compares hillslope sediment
delivery from salvage logging operations implemented to recover economic loss of timber
resources and compares results with previously collected data obtained after the 2015 North
Star Fire in eastern Washington. Given the complexity of hillslope erosion processes, the
focus was to change the total ground cover based on field-observed values and simulate
increasing total ground cover. This research demonstrated that the WEPP model could
simulate erosion within a coefficient of variance of 47% for logging skid trails and within a
variance of 44% for treated logging skid trails. Using the WEPP model to make decisions about post-fire environments and estimating potential impacts from salvage logging
operations on erosion can be a helpful analysis when deciding which areas to log. However,
continued improvement of tools like the WEPP model in conjunction with other methods
quantifying erosion risk will be vital to keeping a defensible approach to environmental
review and avoiding costly litigation.