Climate, grazing and plant interactions : Does climate and grazing shape plant interactions in alpine environments?

Increased knowledge of plant interactions is important for our understanding of how ecosystems will respond to climate changes. Using four common low-herb and three tall- herb species as phytometers I measured the net outcome of plant interactions in an alpine environment by a neighbour removal experiment. Grazing and climate were tested as explanatory factors for differences in the outcome of plant interactions, with two altitudes representing different climates. The most important finding in this experiment is that competition is the dominating interaction among plants in this habitat, regardless of plant size, climate and grazing. Climatic exposure and grazing only influenced tall-herb species while low-herbs were mainly limited by competition, presumably for light. These results are important since facilitative interactions and net facilitation in plant communities are often reported to become more common in severe climates