Forty-eight year decline and fragmentation of aspen (Populus tremuloides) in the South Warner Mountains of California

Aspen (Populus tremuloides Michaux) is a biologically significant component of landscapes in the western United States that has declined throughout its range since European settlement. We used historic (1946) and recent (1994) aerial photographs and a geographic information system (GIS) to compare the amount and fragmentation of aspen in the South Warner Mountains, California. The total area occupied by aspen declined by 24% during this 48-year period. Aspen stands were smaller and more numerous in 1994 than in 1946, contributing to greater overall fragmentation. Restoration of aspen in the South Warner Mountains is a high priority for land managers. The effectiveness of current and past management actions such as prescribed burning, conifer removal, and livestock exclusion should be assessed, and new strategies developed to reverse the decline and ensure the persistence of aspen. (C) 2004 Elsevier B.V. All rights reserved.