Drier, darker and more fertile: 140 years of plant habitat change driven by land-use intensification

摘要

Questions Land-use change is a key driver of biodiversity change. Delayed biotic responses to land-use change impede the establishment of causal links between specific anthropogenic changes and resulting biodiversity change. Therefore, we aimed at investigating changes to plant species pools: (a) at time scales long enough to encompass past land-use changes, even changes that have ceased from collective memory; and (b) at spatial scales wide enough to encompass landscape-wide changes to habitat quantity and quality. Location Denmark, 10 regions in the range 54 degrees 3 '-56 degrees 7 ' N and 10 degrees 4 '-12 degrees 4 ' E. Methods We assessed changes to regional plant species pools over ca 140 years by comparing high-quality legacy data to recent re-surveys in ten Danish regions. To identify anthropogenic drivers of plant compositional change, we assessed ecological properties of winning and losing plant species and compared observed biotic changes to land-cover data spatially and temporally matching the regional flora data. Results Winner species were strongly associated with shaded, fertile, well-drained conditions. Loser species were associated with open, infertile conditions with either moist or xeric soils. The major land-use changes driving biotic change were: (a) drainage of moist and wet biotopes; (b) active afforestation and passive scrub overgrowth due to ceased grazing; and (c) landscape-wide increased nutrient availability. However, the magnitude of increase or decrease in the area of a land-cover type was a poor predictor of the number of habitat-associated winner or loser species. This suggests that degradation of extant biotopes and/or low quality of new biotopes limits plant species richness, in particular of habitat specialists. Conclusions We demonstrate a displacement of plant ecospace towards mesic, shaded and fertile conditions, with profound effects on plant diversity, and mainly driven by intensified agricultural/silvicultural use of the landscape matrix, which has strongly affected the main plant habitats in scattered semi-natural fragments.