Abstract
A central issue in ecology is to understand how species respond to climate change and to predict consequences for community composition and ecosystem functioning. Climate warming causes shifts of species distributions towards the pole, but it is unclear why some species become extremely abundant in new habitats and others not. Plant invasiveness may be caused by a variety of factors. From the perspective of top-down control, the release from natural enemies and subsequent evolution of increased competitive ability are the most prominent hypotheses to explain invasiveness. Plant abundance can be controlled by both above- and belowground enemies. However, enemy release and evolution of invasive plants have been rarely, if ever, considered from a combined above-belowground approach. My aim is to examine how release from above- and belowground enemies influences the evolution and invasiveness of plant species that expand their range from warm into previously cold climate regions. My general hypothesis is that differences in plant abundances between southern species in their new habitats, as well as between southern species in new and original habitats, are caused by differences in mobility between plants, their natural enemies and the predators of the enemies. In order to test my general hypothesis I will relate plant traits of successful and non-successful invaders from southern Europe into The Netherlands to metabolic costs invested in growth and defence in both the original and new habitats. The invaders will be compared with related plant species that are not invasive and with related plant species that are native in the invaded habitats. Furthermore, spatially explicit models will be developed to test spatio-temporal dynamics of plant release from above- or belowground enemies, and their consequences for plant invasiveness in the new habitats. The results will enable me to explain and predict plant invasions due to climate warming.
Netherlands