Long-term effects of livestock grazing in western conifer forests

摘要

Livestock grazing in young regenerating forest is a common way of making beneficial use of ground vegetation. Grazing often continues until tree canopy closure reduces understory forage production to such a low level that grazing is no longer practical. Trees growing on poor sites or within a semi-arid climate zone often are slow to close canopy and may remain as grazeable open canopied forest throughout most of their lives. There is a strong tradition of forest grazing in the Pacific Northwestern, Rocky Mountain, and Southeastern conifer forests of the United States. Approximately one quarter of all forested land in the U.S. is grazed by livestock (USDA 1982).