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RESEARCH PRODUCT

Influence of Two N-Fixing Legumes on Plant Community Properties and Soil Nutrient Levels in an Alpine Ecosystem

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Abstract Low nitrogen (N) supply is a limiting factor for plant growth in most terrestrial ecosystems. N-fixing legumes therefore have the potential to facilitate surrounding vegetation by increasing soil N levels. This effect should be especially pronounced in low-productivity habitats where ambient soil N levels are low, such as in alpine areas. We examined whether plant species composition, community diversity measures, and soil N levels differed with and without the presence of two alpine legumes, Oxytropis lapponica (Wahlenb.) Gay and Astragalus alpinus L., in a Dryas octopetala heath at Finse, Norway. Species composition and richness differed between plots with and without Oxytropis in one of two study sites, as other plant species were positively associated with the legume. None of the measured community properties differed between plots with and without the presence of Astragalus. The contrasting influence of the two legume species corresponds to our findings of higher soil N levels below Oxytropi...