Watersheds Messenger Summer 2002 Vol. IX, No. 2 PDF ISSUE
Contributes to Fire Hazard
Severe wildfires continue to scorch the West, as they have in recent years. Congress has reacted by creating a National Fire Plan that attempts to address some of the factors contributing to the increasing costs of fire-fighting and loss of life and property. Included in the plan are funds for increased fire-fighting capacity, homeowner education and prescribed burning to reduce fuels.
The contribution of livestock to fire hazard is often overlooked, and livestock production continues unabated on public and private lands in the West. While climatic conditions such as extreme drought and high winds are key ingredients in any large blaze, past land management practices, including logging, fire suppression and livestock grazing, have exacerbated the situation by creating densely stocked timber stands that may be more vulnerable to high-intensity fires.
Historically throughout lower-elevation forest and grass ecosystems of the West, fires frequently burned stands with low-intensity blazes, although high-intensity fires may have existed prior to the intervention of white settlers.
Young seedlings and saplings of common tree species such as juniper and ponderosa pine are extremely vulnerable even to moderate levels of heat. As a consequence, low-intensity blazes tended to thin forest stands to create open timber stands dominated by a few widely spaced large trees.
Livestock grazing is frequently overlooked as a significant factor in changing forest stand condition and fire regimes. There is a substantial body of scientific literature that identifies livestock grazing as a major contributor to the alteration of historic fire regimes and a factor in fire hazard.
First, livestock grazing removes the grasses that compete with tree seedlings for water and nutrients. This favors the establishment of deep rooted trees and allows them to dominate the site.
Second, most tree species require bare soil for successful germination. Heavy grazing that removes the grassy understory of many forest sites and creates bare, disturbed soil sites that favor tree establishment has led to greater tree-stocking density.
Third, grazing removes the fine fuels such as grasses that help carry the low-intensity fires that once burned at regular intervals throughout much of the lower-elevation forest ecosystems of the West. This has permitted young saplings and trees to become established and recruited into the forest stand.
Fourth, by permitting a large number of small saplings to become established, competition for water among existing living trees is increased, making trees more vulnerable to insects and other pathogens. Under extreme drought, such trees are actually more flammable than dead trees since internal water content is often less than kiln dried lumber, yet due to the flammable resins found in living trees, drought-stressed trees often explode into flames upon contact with a fire.
Fifth, by contributing to the spread and persistence of fire-prone weedy species such as cheatgrass, livestock production has created far more acres of highly flammable plant communities in many parts of the West.
Despite the contribution of livestock grazing to the growing fire hazard in the West, livestock production on public lands continues unabated and is seldom altered to reduce the incidence or intensity of fires. Wildfires are yet another price to pay for livestock grazing in the West..
George Wuerthner is a Western Watersheds Project advisory board member who lives in Eugene, Oregon.