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abstracts
Antiquity and turnover of North American terrestrial ecosystems since the Last Glacial Maximum
Yao Liu, Simon Brewer, Stephen T. Jackson
We assessed i) antiquity existing ecosystems, and ii) patterns of appearance, persistence, and disappearance of ecosystems since the Last Glacial Maximum. These questions are particularly important for understanding environmental controls of ecosystem properties and the persistence of terrestrial plant ecosystems under future global change scenarios. We undertook two complementary approaches, multivariate analysis and receiver operating characteristic (ROC) analysis, to objectively identify plant ecosystem types from fossil pollen assemblages records over the past 21,000 years in the Neotoma Paleoecology Database. We identified and mapped the transitions of ecosystem types at individual sites in the database to investigate the spatial and temporal pattern of ecosystem turnover in North America.
Our results show that: i) All ecosystems are sensitive to environmental change of the magnitude experienced since the last glacial period; ii) At time scales of decades to millennia, changes in ecosystems generally correlate with changes in climate. The mean ecosystem turnover rate in North America through time showed the same pattern as the magnitude of climate change through the glacial-interglacial period, including abrupt climatic events such as the Younger Dryas at 11-12k BP and the gigadrought at 4.2k BP. The timing of origination and duration of different ecosystems at different places shows some systematic pattern. iii) Ecosystems in some areas persist longer than in other areas. These findings from paleoecological records help us assess the historical range of environmental conditions under which ecosystems are maintained, and identify critical environmental conditions beyond which modern ecosystems may not sustain.
Yao Liu, Department of Botany, University of Wyoming,1000 E. University Ave., University of Wyoming, Laramie, WY, 82071, United States, yliu11@uwyo.edu
Simon Brewer, University of Wyoming, Department of Botany, United States
Stephen T. Jackson, University of Wyoming, Department of Botany, United States
Session: F2: Regional Climate Dynamics
Download Talk:
> YSM09_OralB_YaoLiu.pdf
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