A 4000-YEAR RECORD OF WOODLAND VEGETATION FROM WIND RIVER CANYON, CENTRAL WYOMING

Plant macrofossil analyses of 16 radiocarbon-dated woodrat middens spanning the past 4000 years from the Wind River Canyon region in central Wyoming provide information concerning late Holocene development of juniper woodlands. The study sites are currently dominated by Juniperus osteosperma, with J. scopulorum present locally. Woodlands in the region were dominated by J. scopulorum from ca 4000 yr BP until at least 2800 yr BP. Juniperus osteosperma invaded and expanded before 2000 yr BP This expansion fits a regional pattern of J, osteosperma colonization and expansion in north central Wyoming during a relatively dry period between 2800 and 1000 yr BP. At the time the Wind River Canyon region was colonized by J. osteosperma, the species had populations 50-100 km to both the north and south. Long-distance seed dispersal was required for establishment in the study area. Genetic studies are necessary to identify source populations and regions.