Submitted to: Proceedings Pinyon Juniper Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/17/1994
Publication Date: N/A
Interpretive Summary: Western juniper has expanded dramatically during the past 100 years on interior Pacific Northwest rangelands. The junipers compete with grasses and sagebrush, reducing both forage for livestock and habitat for wildlife. In this paper we review the potential causes of the juniper increases. The probable causes of the increase are: 1) reduction of Native American populations that actively used fire as a vegetation management tool, 2) th removal of fire fuels (forage) and resulting reduction in fire frequency as a result of heavy livestock grazing between 1880 and 1930, and 3) mild temperatures and above average precipitation during the late 1800's and early 1900's. Managing juniper on large areas will require the reintroduction of fire.
Technical Abstract: During the past 100 years there have been dramatic increases in western juniper (Juniperus occidentalis spp. occidentalis) in the western U.S.. Evidence for the increase come from descriptions of explorers and early settlers, old photographs, ring counts of existing trees, and pollen cores taken from pond sediments. A number of factors may have contributed to the western juniper expansion. Most probable among the contributing factors are: 1)reduction or removal of Native American populations that actively use fire as a vegetation management tool; 2)removal of fine fuels, and thus a decline in fire frequency as a result of heavy livestock grazing between 1880 and 1930; and 3)mild temperatures and above average precipitation during the late 1880s and early 1900s. Because young juniper (<50 yr. old) do not survive fires, most factors causing a reduction in fire frequency will tend to favor western juniper.