Increased snow cover causes a shift towards negative neighbor interactions in tundra plant communities.
(English)Manuscript (preprint) (Other academic)
Gradients of increasing environmental harshness are associated with a shift from negative to positive interactions between plants. In alpine ecosystems, the severity of the environment generally increases with altitude and positive interactions between neighboring plants dominate at higher altitudes, while negative interactions dominate at lower altitudes. Similar shifts occur along local topographic gradients, where positive interactions predominate on exposed ridges, while negative interactions are more common in protected habitats. In a recent experiment, it was found that earlier snow-melt caused a shift towards more positive interactions between neighboring plants. This result suggests that differences in the duration of snow cover are responsible for differences in interactions between plants within such habitats. We examined this hypothesis by investigating the effect of longer-lasting snow cover on the intensity and direction of interactions between plants along an environmental gradient from exposed ridges with little natural snow cover to more sheltered fens and heathlands. We recorded a shift from positive interactions with neighbors on exposed ridges to negative interactions with neighbors in heathlands and fens. In accordance with previous studies, the increased snow cover resulted in more negative netinteractions between plants, but the effect was similar in all habitats. Other factors such as nutrient availability, soil humidity or wind exposure might explain these differences between habitats with respect to plant–plant interactions. These results improve our understanding of how abiotic conditions shape species interactions and thus add to our ability to predict how interactions between plants, and thus the composition of plant communities, will change in response to climate change.
IdentifiersURN: urn:nbn:se:umu:diva-30413OAI: oai:DiVA.org:umu-30413DiVA: diva2:282797
Submitted manuscript.2009-12-222009-12-212009-12-22Bibliographically approved