The influence of man-induced land-use change on the upper forest limit in the Romanian Carpathians

The Romanian Carpathians are an important part of Europe’s mountain areas, the actual pattern of forest cover reflecting a long history of land-use practices and management. In the present work, we analyse the recent changes (1945–2018) in the upper forest cover along the 37 mountain units using old topographic maps and Sentinel-2A high-resolution satellite images in order to quantify several spatial indicators related to the upper forest cover and upper forest limit changes. In order to understand the regional variation, we have tested the correlations between the location of the upper forest limit, the local topography and the geographical position. Furthermore, with a view to evaluate the upper forest limit change according to its potential climatic limit, the 10 °C July isotherm was estimated based on WorldClim climate data. In addition, the situations inside and outside the major protected areas were also analysed and discussed so as to assess the possible regional differences as related to human effects. The results revealed a continued downward shift in the mountain areas located below the 1600 m a.l.s., but significant advancement above these values, indicating regional differences in land-use intensity and land management. This study is aimed to increase further knowledge as to the upper forest limit in the European mountains and to provide a baseline for modelling future potential change according to the environmental and anthropogenic variability in the area.