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Effects of interactions between anthropogenic stressors and recurring perturbations on ecosystem resilience and collapse |
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| Authors: | David A Keith Doug H Benson Ian R C Baird Laura Watts Christopher C Simpson Martin Krogh Sarsha Gorissen Jose R Ferrer-Paris Tanya J Mason |
| Institution: | 1. Centre for Ecosystem Science, University of New South Wales, Sydney, New South Wales, Australia;2. Australian Institute of Botanical Science, Royal Botanic Gardens, Sydney, New South Wales, Australia;3. Independent conservation biologist, Katoomba, New South Wales, Australia;4. Centre for Ecosystem Science, University of New South Wales, Sydney, New South Wales, Australia
Australian Institute of Botanical Science, Royal Botanic Gardens, Sydney, New South Wales, Australia;5. Centre for Ecosystem Science, University of New South Wales, Sydney, New South Wales, Australia NSW Department of Planning and Environment, Parramatta, New South Wales, Australia;6. NSW Department of Planning and Environment, Parramatta, New South Wales, Australia;7. School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia |
| Abstract: | Insights into declines in ecosystem resilience and their causes and effects can inform preemptive action to avoid ecosystem collapse and loss of biodiversity, ecosystem services, and human well-being. Empirical studies of ecosystem collapse are rare and hampered by ecosystem complexity, nonlinear and lagged responses, and interactions across scales. We investigated how an anthropogenic stressor could diminish ecosystem resilience to a recurring perturbation by altering a critical ecosystem driver. We studied groundwater-dependent, peat-accumulating, fire-prone wetlands known as upland swamps in southeastern Australia. We hypothesized that underground mining (stressor) reduces resilience of these wetlands to landscape fires (perturbation) by diminishing groundwater, a key ecosystem driver. We monitored soil moisture as an indicator of ecosystem resilience during and after underground mining. After landscape fire, we compared responses of multiple state variables representing ecosystem structure, composition, and function in swamps within the mining footprint with unmined reference swamps. Soil moisture declined without recovery in swamps with mine subsidence (i.e., undermined), but was maintained in reference swamps over 8 years (effect size 1.8). Relative to burned reference swamps, burned undermined swamps showed greater loss of peat via substrate combustion; reduced cover, height, and biomass of regenerating vegetation; reduced postfire plant species richness and abundance; altered plant species composition; increased mortality rates of woody plants; reduced postfire seedling recruitment; and extirpation of a hydrophilic animal. Undermined swamps therefore showed strong symptoms of postfire ecosystem collapse, whereas reference swamps regenerated vigorously. We found that an anthropogenic stressor diminished the resilience of an ecosystem to recurring perturbations, predisposing it to collapse. Avoidance of ecosystem collapse hinges on early diagnosis of mechanisms and preventative risk reduction. It may be possible to delay or ameliorate symptoms of collapse or to restore resilience, but the latter appears unlikely in our study system due to fundamental alteration of a critical ecosystem driver. Efectos de las interacciones entre los estresantes antropogénicos y las perturbaciones recurrentes sobre la resiliencia y el colapso de los ecosistemas |
| Keywords: | ecosystem collapse fire groundwater hydrology Newnes Plateau Shrub Swamp peatland red list of ecosystems regime shift underground mining cambio de régimen colapso ecosistémico hidrología de aguas subterráneas lista roja de ecosistemas minería subterránea pantano arbustivo de la meseta Newnes turbera 生态系统崩溃 稳态转变 泥炭地 纽恩高原灌木沼泽 火灾 地下采矿 地下水水文学 生态系统红色名录 |