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Crist, Patrick J
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Critical slowing down as early warning for the onset of collapse in mutualistic communities
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Tipping points are crossed when small changes in external conditions cause abrupt unexpected responses in the current state of a system. In the case of ecological communities under stress, the risk of approaching a tipping point is unknown, but its stakes are high. Here, we test recently developed critical slowing-down indicators as early-warning signals for detecting the proximity to a potential tipping point in structurally complex ecological communities. We use the structure of 79 empirical mutualistic networks to simulate a scenario of gradual environmental change that leads to an abrupt first extinction event followed by a sequence of species losses until the point of complete community collapse. We find that critical slowing-down indicators derived from time series of bio- masses measured at the species and community level signal the proximity to the onset of community collapse. In particular, we identify specialist species as likely the best-indicator species for mon- itoring the proximity of a community to collapse. In addition, trends in slowing-down indicators are strongly correlated to the timing of species extinctions. This correlation offers a promising way for map- ping species resilience and ranking species risk to extinction in a given community. Our findings pave the road for combining theory on tipping points with patterns of network structure that might prove useful for the management of a broad class of ecological networks under global environmental change.
resilience | critical transition | mutualism | ecological networks | pollinator decline
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Climate Science Documents
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Cross-scale Drivers of Natural Disturbances Prone to Anthropogenic Amplification: The Dynamics of Bark Beetle Eruptions
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Biome-scale disturbances by eruptive herbivores provide valuable insights into species interactions, ecosystem function, and impacts of global change. We present a conceptual framework using one system as a model, emphasizing interactions across levels of biological hierarchy and spatiotemporal scales. Bark beetles are major natural disturbance agents in western North American forests. However, recent bark beetle population eruptions have exceeded the frequencies, impacts, and ranges documented during the previous 125 years. Extensive host abundance and susceptibility, concentrated beetle density, favorable weather, optimal symbiotic associations, and escape from natural enemies must occur jointly for beetles to surpass a series of thresholds and exert widespread disturbance. Opposing feedbacks determine qualitatively distinct outcomes at junctures at the biochemical through landscape levels. Eruptions occur when key thresholds are surpassed, prior constraints cease to exert influence, and positive feedbacks amplify across scales. These dynamics are bidirectional, as landscape features influence how lower-scale processes are amplified or buffered. Climate change and reduced habitat heterogeneity increase the likelihood that key thresholds will be exceeded, and may cause fundamental regime shifts. Systems in which endogenous feedbacks can dominate after external forces foster the initial breach of thresholds appear particularly sensitive to anthropogenic perturbations.
Keywords: thresholds, plant-insect interactions, landscape disturbance, forest management, anthropogenic change
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Climate Science Documents
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Crowley 1957.pdf
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TRB Library
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COO-CVA
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Croy, Steve
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Culbreth Tissues.pdf
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COO-CVA
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Cultural Landscapes
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Landscapes, the visible features of an area like mountains or rivers or skylines, house an abundant of riches and dynamic relationships. They can range from thousands of acres of farm land to an historic seaport, from a Civil War battlefield to the pristine wilderness of some of our most cherished national parks. There are natural landscapes and human-dominated landscapes and cultural landscapes.
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Integrating Cultural Resource Preservation at a Landscape Level
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Cultural Resources Fellowship
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Cultural Landscapes Screenshot
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Cultural Landscapes Screenshot
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Cumberland - Southern Appalachian Climate Change Vulnerability Species Assessments
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These results are a compilation of climate change vulnerability assessments in the southeastern portion of the LCC, covering the area from southern West Virginia, south to Alabama, west to eastern Kentucky and Tennessee. Hyperlinks to additional information are separated into two additional spreadsheets, one for aquatic and subterranean, and another for terrestrial species.
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Assessing Vulnerability of Species and Habitats to Large-scale Impacts
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Vulnerability Assessment Foundational Data by Subregion
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Cummings 1991.pdf
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