Comparative Rates of Western Juniper Afforestation in South-Central Oregon and the Role of Anthropogenic Disturbance*

نویسندگان

  • Peter T. Soulé
  • Paul A. Knapp
  • Henri D. Grissino-Mayer
چکیده

We examine changes in canopy cover for adult western juniper from the 1960s to 1994 in central Oregon using repeat aerial photography. We compare changes at four sites with a land-use history of minimal anthropogenic disturbance to changes on adjacent sites that have a disturbance history more typical of central Oregon rangelands. Canopy cover increased at all sites, but afforestation on sites with domestic livestock grazing was greater. The potential driving forces common to all sites include a long fire-free interval, early twentiethcentury favorable climatic conditions, biological inertia, and atmospheric CO2 enrichment.

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تاریخ انتشار 2003