Vortragsreihe Ökologie und Umweltforschung SS 2009

Plant-plant interactions & biodiversity - and their connection to the restoration of degraded sites

Vortrag im Rahmen des GCE (eingeladen durch Beierkuhnlein).

Positive interactions between plants and their knock-on effects on the functioning of ecosystems are receiving increasing attention in ecological research. In addition, biodiversity-ecosystem functioning experiments have often found positive effects of mixtures of species with different functional traits on ecosystem productivity and nutrient cycling. The challenge now is to address the question of how relevant positive interactions found in biodiversity experiments are under different environmental settings. It could be that environmental factors such as the availability of nutrients override any positive biodiversity effects in one habitat, whereas in other habitats the effects act synergistically.

According to the stress gradient hypothesis (Callaway XX), positive interactions between plants should increase, as one move from a less stressed to a highly stressed (harsh) environment. In my group we are testing positive interactions (usually found in mesic grassland biodiversity experiments) across nutrient stress gradients both in the field and in controlled glasshouses and climate chambers to see if they become stronger under nutrient stress. In the case of more positive interactions and concomitant positive effects on functioning of ecosystems, this should prove to be very useful in applying to degraded ecosystem needing restoration (such as ex-mining sites, eutrophic sites. The particular focus is on N2-fixing plants and their positive effects on neighbours as modulated by the diversity of the mixtures, and we use stable isotope techniques to investigate these questions.

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