Spatial patterns and dynamic responses of arctic food webs corroborate the exploitation ecosystems hypothesis (EEH)
| Autor: | Üllar Rammul, Hans Olav Hygen, Bernt Johansen, Jonas Dahlgren, Michael Schneider, Doris Grellmann, Lauri Oksanen, Tarja Oksanen, Johan Olofsson, Maano Aunapuu |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Food Chain
Population Dynamics Foxes Plant Development Biology complex mixtures Models Biological Charadriiformes Mustelidae Animals Ecosystem Biomass Trophic cascade Ecology Evolution Behavior and Systematics Falconiformes Population Density Biomass (ecology) Herbivore Ecology Arctic Regions Arvicolinae Norway fungi food and beverages Feeding Behavior Food web Tundra Hawks Productivity (ecology) Fertilization Predatory Behavior Terrestrial ecosystem |
| Zdroj: | The American naturalist. 171(2) |
| ISSN: | 1537-5323 |
| Popis: | According to the exploitation ecosystems hypothesis (EEH), productive terrestrial ecosystems are characterized by community-level trophic cascades, whereas unproductive ecosystems harbor food-limited grazers, which regulate community-level plant biomass. We tested this hypothesis along arctic-alpine productivity gradients at the Joatka field base, Finnmark, Norway. In unproductive habitats, mammalian predators were absent and plant biomass was constant, whereas herbivore biomass varied, reflecting the productivity of the habitat. In productive habitats, predatory mammals were persistently present and plant biomass varied in space, but herbivore biomass did not. Plant biomass of productive tundra scrublands declined by 40% when vegetation blocks were transferred to predation-free islands. Corresponding transfer to herbivore-free islands triggered an increase in plant biomass. Fertilization of an unproductive tundra heath resulted in a fourfold increase in rodent density and a corresponding increase in winter grazing activity, whereas the total aboveground plant biomass remained unchanged. These results corroborate the predictions of the EEH, implying that the endotherm community and the vegetation of the North European tundra behaves dynamically as if each trophic level consisted of a single population, in spite of local co-occurrence of20 plant species representing different major taxonomic groups, growth forms, and defensive strategies. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|