Ecological memory is central to how ecosystems respond to disturbance and is maintained by two types of legacies – information and material. Species life-history traits represent an adaptive response to disturbance and are an information legacy; in contrast, the abiotic and biotic structures (such as seeds or nutrients) produced by single disturbance events are material legacies. Disturbance characteristics that support or maintain these legacies enhance ecological resilience and maintain a “safe operating space” for ecosystem recovery. However, legacies can be lost or diminished as disturbance regimes and environmental conditions change, generating a “resilience debt” that manifests only after the system is disturbed. Strong effects of ecological memory on post-disturbance dynamics imply that contingencies (effects that cannot be predicted with certainty) of individual disturbances, interactions among disturbances, and climate variability combine to affect ecosystem resilience. We illustrate these concepts and introduce a novel ecosystem resilience framework with examples of forest disturbances, primarily from North America. Identifying legacies that support resilience in a particular ecosystem can help scientists and resource managers anticipate when disturbances may trigger abrupt shifts in forest ecosystems, and when forests are likely to be resilient.
Bibliographical noteFunding Information:
This work arose from an oral session – at the 2014 annual meeting of the Ecological Society of America – organized by JFJ and MGT. All authors contributed ideas and text to the final manuscript. Support to individual authors was provided by: Bonanza Creek Long-Term Ecological Research (to JFJ and MCM), Joint Fire Science Program (grant 11-1-1-7 to MGT, GRIN 12-3-10 to BJH); Natural Science and Engineering Research Council of Canada (RGPIN 341774-20 to JFJ); Strategic Environmental Research and Development Program (project RC-2109 to JFJ and MCM); US Geological Survey's Ecosystems and Climate & Land Use Change mission areas, Western Mountain Initiative (to CDA); US National Park Service–George Melendez Wright Climate Change Fellowship (to BJH); US National Science Foundation (DEB-EF-0622770 to RKM and MRM, IIA-0966472 and ARC-1023669 to PEH); and the Wilderness Research Foundation (to LEF).
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