Landscape Influences on Recent Timberline Shifts in the Carpathian Mountains: Abiotic Influences Modulate Effects of Land-Use Change

摘要

Expected shifts in the upper forest limit of many mountain ranges due to anthropogenic climate change will likely be constrained by current and historical land-use practices. We used historical maps and Landsat satellite imagery to analyze timberline change for the entire Carpathian range in Eastern Europe. Our objectives were (1) to compare 19th and 20th century timberline elevations across regions differing in sociopolitical history and land-use trends; and (2) to quantify how land-use patterns and environmental influences were associated with changes in timberline position. Timberline changes across geopolitical regions were consistent with regional variations in re-settlement rates and population shifts following World War II. Important predictors for timberline rise were the mainly biophysical factors of slope steepness, timberline elevation, shrub cover, topographic curvature, aspect, and proximity to roads. For horizontal migration, important predictors were proximity to shepherd’s huts, elevation, population density, forest composition, and shrub cover. Overall, cultural influences were critical for understanding the response of Carpathian timberlines to global change, yet biophysical influences proved important where reforestation was already occurring. In mountain ranges with prevalent agricultural abandonment, forest migration associated with climate warming may lead to increased contrast in the forest-alpine ecotone between areas with and without intensive land-use.