Format: ORAL

Sabine Rumpf1

1 Department of Environmental Sciences, University of Basel, Switzerland

Mountain ecosystems remain comparatively natural and harbor disproportionately high levels of biodiversity. Yet, they are warming about twice as fast as the global average and are additionally affected by nitrogen depositions from the lowlands. Recent warming caused individuals of plant species already previously present to grow taller, and the overall plant community height increased. This increase of community height is, however, not only driven by intraspecific trait variation. The composition of plant species communities changed as well. A few plant species increased substantially in abundance at the expense of the majority of species which decreased in abundance. In addition, species shift their ranges to higher elevations to track the climatic conditions they are adapted to. Taller-growing nutriphilous and thermophilic species from lower elevations seem to profit by shifting their distributions faster than the less competitive, more specialized and unique flora of higher elevations. These trends led together to a significant greening of the European Alps above the tree line. Yet, the vast majority of species is lagging behind recent trends, implying that even if climate change was halted now, its effects were likely to continue. Climate warming is, however, not slowing down but is rather accelerating. Potentially increasing lags might therefore become too large to overcome in the future, resulting in species extirpations. These local to regional extirpations might be reinforced by more competitive and faster shifting neophytes that start to arrive and spread in mountain ecosystems. Predicting these future responses of alpine plant species to global change is crucial to conserve global biodiversity. For accurately predicting the future it is, however, inevitable to first understand the past and its legacy effects.