Interpreting Long-Term Trends in Blue Mountain Ecosystems from Repeat Photography

摘要

Photographs taken before 1925 were compared with photos taken as recently as 1992to interpret changes within ecosystems in the Blue Mountains of Oregon. Nearly all systems exhibited some degree of conversion from herbaceous to woody forms of vegetation. Nonforested ecosystems improved markedly except in the riparian-aquatic habitats. Forested ecosystems were stressed from stand stagnation, conversion from pine to fir, serious insect infestations, and crown fires. This project shows how these ecosystems have changed since the advent of settlement by nonendemic people. It was carried out to assist land managers and researchers to develop strategies to improve ecosystem stability and thereby provide for resource sustainability.