PARENT SESSION
Oral Session #15: Paleoecology and Climate Change.
Presiding: J. Betancourt
Monday, August 5. 1:00 PM to 3:45 PM. Graham Meeting Room, TCC.
Rapid and widespread vegetation responses to late-glacial climate change in the North Atlantic region.
Williams, John*,1, Post, David1, Cwynar, Les2, Lotter, Andre3, Levesque, Andre2, 1 National Center for Ecological Analysis and Synthesis, Santa Barbara, CA2 University of New Brunswick, Fredericton, New Brunswick, Canada3 University of Utrecht, Utrecht, The Netherlands
ABSTRACT- The increased risk of future rapid climate changes, due to anthropogenic modifications of the biosphere and atmosphere, has created interest in understanding the ability of natural systems to respond to abrupt climate change. However, vegetation responses to climate change at timescales of decades to centuries remain poorly understood, falling in a gap between the timescales typical of ecological study (days to years) and those typical of paleoecology (centuries to millennia). We have conducted a systematic survey of eleven lake sediment records from the North Atlantic region with 1) high-resolution records spanning the last deglaciation and 2) proxies for past vegetation composition (pollen) and climate (oxygen isotopes and chironomid assemblages). Cross-correlation analysis of the paired time series indicates significant cross-correlations between the vegetation and climate proxies at all sites. Vegetation response times are consistently <200 years and often <100 years, despite regional differences in physiography and species composition. Arboreal and non-arboreal plant taxa have similarly short response times. Our data synthesis thus suggests that widespread and nearly synchronized alterations in vegetation composition and plant distributions will quickly follow any future climate change, and that such responses will persist for several centuries after the initial perturbation. Vegetation responses to future climate change, however, will have to contend with other anthropogenic modifications to the landscape.
KEY WORDS: vegetation, climate, pollen