Changes in Forest Cover and its Diversity

Current forest cover of Europe differs not only from its past area or pattern, but also from Europe’s potential vegetation. This is a result of two main factors, i.e. climate changes and the anthropogenic influence. Both factors have affected tree species composition of forests, forest coverage, fragmentation, the structure of forest ecosystems, as well as their texture. Generally, they acted in opposite ways: while the easing of harsh climate after the last glaciation facilitated the re-colonisation of land by trees and further development of forest ecosystems, forest areas have been reduced and fragmented, and their structure and biodiversity diminished due to human activities. A reversal of the latter trend occurred during the last century in Europe, a process also called forest cover transition. It has been initiated and sustained by the decline of agriculture and population drift into urban areas. This trend has enabled both natural and artificial reforestation and/or afforestation, respectively. It is necessary to understand these changes because of their profound impact on both current forest management options and the water cycle. Various modes of impact may result from distinct ecophysiological responses of tress to the soil water content, interception and water channelling through forest canopies, coarse woody debris and surface humus layer, as well as structures and force fields created by tree roots and soil edaphone. Thus, projected scenarios of the development of European forests in the next decades imply multiple effects on the water cycle.