Herbicides

For background information and additional context, please see our Tree Mortality and Fire page.

In the Coast Range, a lack of markets for low-value hardwoods has resulted in some forest managers using selective chemicals to individually treat and kill those trees. As with SOD, herbicide-related fire risk changes through time and depends on the proximity of herbicide-killed trees to homes and community infrastructure. Herbicide treatments do contribute to fuel loading, yet they offer the unique advantage of being targeted in location and extent (compared with bark beetles, wildfire, and SOD, for instance); this can increase accessibility for subsequent treatment or removal of dead trees, or suppression response, if there is an unwanted ignition in an herbicide-treated stand. Herbicide-related fuels will dissipate with time (as shown in the graphic below) and typically have only one pulse event unlike sustained mortality from sudden oak death, drought, or bark beetles.

Valachovic, Y.S., Lee, C.A., Scanlon, H., Varner, J.M., Glebocki, R., Graham, B.D. and Rizzo, D.M., 2011. Sudden oak death-caused changes to surface fuel loading and potential fire behavior in Douglas-fir-tanoak forests. Forest Ecology and Management, 261(11), pp.1973-1986. http://www.fs.fed.us/psw/publications/uesd/psw.2011.valachovic.SODcausedchanges.FEM.pdf