Vortrag, International Biogeographical Society meeting: Climate Change Biogeography, Évora, Portugal: 20.03.2018 - 24.03.2018
Climate change is a serious threat to the oceanic island flora. Accurate knowledge on precipitation change is missing due to high uncertainties in global climate models impeding their transfer to island climate conditions. Mountainous oceanic islands in the subtropics have a particular diverse climate because of the trade wind influence. For our model island La Palma (Canary Islands), we developed different precipitation scenarios to investigate potential future distribution changes of endemic species. Five possible scenarios of future precipitation changes were compared with current precipitation: (1) an increase of dry season length, (2) an increase of the inter-annual precipitation variability, (3) a divergence of precipitation extremes (dry areas get dryer, wet areas wetter), (4) a decrease of the mean annual precipitation (due to an increase in altitude of the trade wind cloud layer) and a scenario with (5) less precipitation for high elevations and more precipitation for low elevations (due to a decrease in altitude of the trade wind cloud layer). We combined these six scenarios with two temperature predictions based on RCP trajectories 4.5 and 8.5, respectively. These scenarios also incorporate an elevation-dependent temperature change because of a low elevation ocean buffer. Then, we calculated species distributions based on the current climate and projected them using the different scenarios. Furthermore, we analysed potential distances between current and future areas of similar environmental conditions on the island scale. We present small-scale precipitation scenarios as helpful tools to assess future challenges of endemic species in climatically complex areas like oceanic islands.