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The role of plant–soil feedbacks in stabilizing a reindeer‐induced vegetation shift in subarctic tundra

Author:
Egelkraut, Dagmar, Kardol, Paul, De Long, Jonathan R., Olofsson, Johan
Source:
Functional ecology 2018 v.32 no.8 pp. 1959-1971
ISSN:
0269-8463
Subject:
Betula nana, Potentilla, biomass, community structure, forbs, gamma radiation, habitats, herbivores, herding, landscapes, meadows, milking, nitrogen, nitrogen content, nutrient availability, plant communities, plant growth, plant response, reindeer, shrubs, soil, soil minerals, soil-plant interactions, tundra, Sweden
Abstract:
Herbivory can drive vegetation into different states of productivity and community composition, and these changes may be stable over time due to historical contingency effects. Interactions with abiotic and biotic soil components can contribute to such long‐term legacies in plant communities through stabilizing positive feedbacks. We studied the role of plant–soil feedbacks in maintaining vegetation changes caused by historical (~1350–1900 AD) reindeer herding in northern Sweden. These historical milking grounds (HMGs) consist of meadow plant communities formed in naturally nutrient‐poor heath or naturally nutrient‐rich shrub‐dominated vegetation and are still clearly visible in the landscape, a century after active use ceased. We selected two phytometer species: the forb Potentilla crantzii as representative of HMG vegetation, and the dwarf shrub Betula nana, as representative of control vegetation. We grew both species under glasshouse conditions on soils derived from replicated HMG and paired control plots, using live soils and sterilized (γ‐radiation)‐inoculated soils, to separate between biotic and abiotic soil effects. A net negative plant–soil feedback for B. nana biomass in its home (i.e., control) soil and a net positive feedback for P. crantzii in its home (i.e., HMG) soil in heath habitat was partly driven by the soil biotic community. However, abiotic differences in mineral nitrogen (N) concentrations between control and HMG soils were a stronger driver of differences in plant growth. Positive feedbacks maintaining a high mineral nutrient availability are thus important, especially in nutrient‐poor habitats. The positive plant responses to higher soil mineral N concentrations, combined with positive biotic plant–soil feedbacks, might shift the competitive balance in favour of typical HMG plant species, thereby contributing to stability of HMG plant communities. Our data indicate that herbivore‐driven changes in the interactions between plants and both biotic and abiotic components of the soil persist over long temporal scales. A plain language summary is available for this article.
Agid:
6083024