Abstract:

Treatments of prescribed fire and chaining have been widely applied across the Great Basin since the mid 20th century in an effort to reduce pinyon and juniper cover and stimulate understory growth. Treatment efforts often result in altered vegetation structure and composition relative to untreated areas. A few studies have examined short-term effects of chaining and prescribed fire treatments, but this study examined long-term changes in vegetation cover, tree survivorship, and tree establishment multiple decades after historical treatments. This study revisited sites of woodland treatments that were originally sampled over 30 years ago. An emphasis was placed on tree recovery because it is an easily interpretable measure of treatment success.

Changes in vegetation composition were evaluated by collecting vegetation cover, soil depth, and soil texture data at plots within four chaining sites treated in 1958, 1962, 1968, and 1969 and originally sampled in 1971. The same data were collected at five prescribed burn sites treated in 1975 and originally sampled in 1976. Tree age data were collected at every chaining and prescribed fire plot by sampling increment cores and stem cross sections.

Although prescribed fires more closely met resource management goals of the mid 20th century, managers may find the practice too risky when considering current environmental conditions and management concerns. Prescribed burning was more successful than chaining for removing trees, maintaining understory communities, and causing reduced post-treatment tree establishment. However, cheatgrass ( Bromus tectorum ) was present at prescribed fire sites and not chaining sites. The great increases of tree cover in the untreated areas of this study indicate fuel loads are much larger than when the prescribed fires were conducted in 1975. The risk of an escaped fire becoming a conflagration has increased since then, as has the risk of cheatgrass invasion.

Funding provided by: US Department of Interior Bureau of Land Management

Project duration: September, 2007 - August, 2010

Presentations:

Bristow, N., Weisberg, P., and R. Tausch. 2010. Differential recovery of sagebrush steppe Pinyon-Juniper type vegetation multiple decades after treatments of prescribed fire and chaining.Wildland Shrub Symposium, Logan, Utah, oral presentation.

Bristow, N., Weisberg P., and R. 2008. Tausch. Succession over 30 years following natural and anthropogenic disturbance in Great Basin pinyon-juniper woodlands. Annual Meeting of the International Association for Landscape Ecology. Madison , WI, poster presentation.