Changes in forest cover in Sudety Mountains during the last 250 years: patterns, drivers, and landscape-scale implications for nature conservation
Historical ecology gives a reference point to explain the contemporary state of particular ecosystems as well as entire landscapes. In this study, we examined the quantitative changes in forest cover in the central part of the Sudety Massif (area ca. 1,120 km<sup>2</sup>) during the last 250 years. The information regarding forest patch distribution and its changes was derived by comparison of maps from 1747 and the 1970s drawn at scales of 1:33,000 and 1:25,000, respectively. To examine the effect of environmental variables (topography and soil conditions) and human population density on forest patch distribution and its changes (afforestation, deforestation), a set of 100 circular plots with a diameter of 1 km was established. The influence of explanatory variables was examined using regression tree methods. Changes at the level of the entire landscape were tested using a set of 25 landscape windows (5 × 5 km each). We found that the overall forest cover increased to 36.4% in the twentieth century from 30.4% in the middle of the eighteenth century. The ancient forests constituted 59% of the total forest area existing more recently. The forests in the eighteenth century occurred mostly on steep slopes, deep valley bottoms, and summits. The land relief explains more than half of the total variation in forest distribution (<em>R</em><sup>2</sup> = 0.56). The effects of soil type and human population density were negligible. The contemporary forest pattern results from both land relief and the historical pattern of human population density in the middle of the eighteenth century (<em>R</em><sup>2</sup> = 0.64), while the effect of soil type was negligible. The pattern of deforestation (<em>R</em><sup>2</sup> = 0.53) and afforestation (<em>R</em><sup>2</sup> = 0.36) results from both land relief as well as recent and nineteenth-century human population density. About 83% of the recent forest area is in physical contact with patches of the ancient forest, which provides an optimistic outlook for the migration of ancient forest species into new areas. Furthermore, changes in landscape structure reveal increased connectivity among forest patches, with potential benefits for the migration of forest species with long-range dispersal.
