Science Findings, Issue 141, April 2012. A Closer Look: Decoupling the Effects of Prescribed Fire and Grazing on Vegetation in a Ponderosa Pine Forest

摘要

Scientists have had little information about how prescribed fire and cattle grazingcommon practices in many Western ponderosa pine forestsaffect plant abundance and reproduction in the forest understory. Pacific Northwest Research Station scientists began to explore how these practices affect vegetation in a five-year study of postfire vegetation in eastern Oregon ponderosa pine forests where cattle have been routinely pastured from late June or early July through early to mid August. For this area of eastern Oregon, they found that excluding cattle grazing during peak growing season increased native plant cover and grass flowering capability in ungrazed areas compared to grazed areas. Because vegetation was measured prior to releasing cattle on the land, the study's results tend to reflect lasting grazing impacts rather than simple consumption. Findings indicate that excluding cattle in areas that had been exposed to long-term grazing had more effect on vegetation than reintroducing frequent fire to the landscape.