Long‐term effects of prairie restoration on plant community structure and native population dynamics |
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| Authors: | Charlotte C. Trowbridge Amanda Stanley Thomas N. Kaye Peter W. Dunwiddie Jennifer L. Williams |
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| Affiliation: | 1. Department of Geography, University of British Columbia, Vancouver BC, Canada;2. Wilburforce Foundation, Seattle, WA, U.S.A.;3. Institute for Applied Ecology, Corvallis, OR, U.S.A.;4. Department of Biology, University of Washington, Seattle, WA, U.S.A.;5. Department of Geography and Biodiversity Research Centre, University of British Columbia, Vancouver BC, Canada |
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| Abstract: | The key to restoring degraded grassland habitats is identifying feasible and effective techniques to reduce the negative impacts of exotic species and promote self‐sustaining native populations. It is often difficult to extend monitoring of restoration efforts to evaluate long‐term success, but doing so is essential to understanding how initial outcomes change over time. To assess how initial treatment effects persist, we revisited degraded patches of Pacific Northwest prairie habitat 6 years after experimental restoration efforts ceased. We evaluated plant community composition to determine the lasting effects of supplemental native seeding and disturbance treatments (burning, mowing, and herbicide to reduce exotic species). We tracked the persistence of seeded species and measured spread of their populations to evaluate suitability of species for restoration and the ability of the habitat to support native plant populations. We found that plots that received supplemental seeding continued to exhibit higher richness of native species than those left unseeded, and that both seeding and disturbance treatments could positively influence native species abundance over the long term. The initially observed effects of disturbance treatments on reducing exotic grass abundance had diminished, highlighting the importance of long‐term monitoring and ongoing control of exotic species. Nevertheless, these treatments significantly influenced the population trajectories of 4 out of 8 seeded native species. There was evidence of spatial advance of most seeded species. Results from extended monitoring confirm that dispersal limitation of native species and difficulties maintaining the reduction of exotic grasses continue to be major barriers to success in restoration of invaded grasslands. |
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| Keywords: | invasive grasses native seeding plant diversity population spread prairies restoration success seed limitation |
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