MULTIDECADAL-TO-CENTENNIAL SCALE ECOLOGICAL DYNAMICS DURING TIMES OF ABRUPT HOLOCENE VEGETATION CHANGE

Quaternary paleoecology has provided valuable insight into millennial-scale responses of ecosystems to environmental change, whereas ecological processes operating at annual to decadal timescales have been an important focus of contemporary ecological studies. However, there is a significant gap in our understanding of ecological processes and ecosystem dynamics at intermediate timescales (i.e., multidecadal-to-centennial), and these timescales are especially relevant to understanding and potentially forecasting ecological changes that occur during and immediately following time periods of rapid environmental change. Recent developments in age–depth modeling, as well as improved techniques of paleoecological and paleoclimatic inference, are allowing richly detailed examinations of abrupt ecological transitions, including assessments of temporal synchroneity and lags in response of vegetation to changes in climate and disturbance with appropriate uncertainty estimates. Here I compare and contrast new and recently developed high-resolution analyses of vegetation, disturbance, and climate during several time periods of abrupt environmental change in the Holocene, using a network of records from peatlands in midcontinental and eastern North America. Focal ecological transitions include the mid-Holocene hemlock decline and late-Holocene changes in forest composition in the Great Lakes region and the Northeast. Results indicate differences in the relative timing of climatic, vegetation, and fire events across these ecological transitions, as well as similarities and differences in the characteristics of multidecadal changes in vegetation and fire. Patterns are used to develop hypotheses of underlying ecological dynamics (e.g., tree mortality, changes in recruitment), and highlight that similarly high resolution analyses across these and other time periods will significantly contribute to our understanding of the drivers, ecological processes, and spatiotemporal dynamics of past abrupt vegetation change.