Der Rückgang von lichten Waldstrukturen und Waldlücken und die Auswirkungen auf Vegetation und Bestäuber

The decline of sparse forest structures and forest gaps and the effects on vegetation and pollinators // Forest gaps are considered as small natural features with large ecological roles. In the Danube valley near Passau, forest gaps decreased by 88 % between 1945 and 2020. The abandonment of historical and recent forms of forest use as well as anthropogenic nutrient depositions from atmosphere are identified as the causes. Our study confirms this because of a significantly increased Ellenberg indicator values for soil nutrients in the vegetation. Red List species in vegetation and specialised bees declined. The effects of climate change were clearly visible in the change of species composition of the wild bee community. Our experiments have shown that the overgrowth of forest gaps has a negative impact on the pollination function, from flower supply to flower visitation to seed set. For this reason, nature conservation in forests that still harbour organisms typical of light forests should focus more on the preservation and new creation of forest gaps.