Shaded fuel break in Plumas National Forest, Lassen County, California	Fuel break in Mendocino National Forest, Lake County, California	Fuel break in Santa Monica Mountains National Recreation Area, Ventura County, California

This project investigates the role of pre-fire fuel reduction manipulation projects on the invasion of nonnative plants. These projects generally include mechanical fuel reduction treatments designed to control fire behavior, break up landscape fuels, and improve access for fire suppression. They vary in design from linear features such as fuel breaks and fire lines, to large, thinned areas with some remaining overstory canopy cover, sometimes referred to as shaded fuel breaks. Fuel breaks are an increasingly important component of state and federal fuels management programs, such as the National Fire Plan and the Healthy Forest Initiative. Unfortunately, an unexpected result of some pre-fire fuel manipulation projects may be the introduction of nonnative invasive plants. Fuel breaks may promote the establishment of nonnative invasive plants by disturbing soils, increasing light levels, and changing soil nutrients and hydrology. Fuel break maintenance activities, such as thinning and prescribed burning, also may provide disturbance regimes that favor invasive species. Equipment may disperse the seeds of nonnative plants into fuel breaks during construction and maintenance. The establishment of alien plants within fuel treatments is a serious concern because many treated areas extend into remote, pristine wildland areas. If alien species can establish a seed source in fuel breaks, adjacent wildland areas might become be more susceptible to widespread invasion, particularly following wide spread disturbances such as natural or prescribed fires. This study is designed to answer the following questions: Do nonnative plants become established within fuel breaks? Are some types of fuel breaks less likely to support nonnative species? Do fuel breaks promote the invasion of nonnative plants into adjacent wildland areas after disturbances such as fire? We hope this work will provide information to resource and fire managers that will help them design, construct, and maintain fuel breaks that are less likely to promote the spread of nonnative plants. If you would like to be added to a mailing list to receive technical reports and additional information about this study, please email Kyle Merriam.

This study is funded by the Joint Fire Science Program