Vortrag (eingeladen), Biologische Zentrum Klein Flottbek, University of Hamburg, Hamburg: 20.05.2015
High elevation islands, especially in the tropics and subtropics, are global hotspots of plant diversity. Owing to their isolation and strong environmental gradients their exceptional position in terms of diversity results in large parts from in-situ speciation, leading to the evolution of endemic species. Thus, understanding the underlying drivers of diversity and the disturbances that shape them may offer fundamental insights into general ecological processes. However, patterns and processes are often scale-dependent. Thus, the talk will aim at crossing scales from local to global, also bridging between disciplines such as island biogeography, island ecology, disturbance ecology and invasion ecology. On the global scale, the talk will attempt a tentative classification of high elevation islands, and discuss possible drivers of island treeline formation using an innovative sampling approach (GoogleEarth). On the regional to local scale a focus will be put on the drivers of spatial patterns of species richness and endemism, and assess the impact of major human-mediated disturbances (introduced herbivores, fire, roads) on the endemic flora of our model island La Palma, Canary Islands. Due to the continental-scale environmental gradients on the landscape scale of a medium-sized oceanic island, it is justifiable to call La Palma a climatic mini-continent, highlighting that the insights gained here might be relevant for other non-insular systems.