Abstract Detail



Paleobotany

Carroll , Hannah M [1], Wanamaker, Alan D [2], Clark, Lynn [3], Wilsey, Brian [1].

Ambrosia and Artemisia pollen can distinguish between vegetation types at broad spatial scales.

Vegetation distributions at regional to subcontinental scales are a result of the interaction between climate, dispersal, disturbance, and competition over millennia. These complex processes serve to create distinct regions of potential habitat which change dramatically over geologic time in response to both external and internal forcings. The communities present in any given habitat, at any given time, are both responding to and driving changes at localized scales that translate into broad patterns of distribution. While individual species may interact in mutually beneficial or antagonistic ways, or anything in between, ultimately their distribution is driven by climate tolerance. Known tolerances are widely used to understand past climate, but can also be employed to reconstruct past ecoregion boundaries. Two common genera, Ambrosia and Artemisia, are widely distributed and overlap for much of their range, but respond very differently to temperature and moisture gradients. They are both present in the majority of pollen datasets, are readily distinguishable, and among the standard taxa reported in contributions to the Neotoma Paleoecology Database and the North American Pollen Database. We obtained 538 surface pollen records and 793 modern pre-European settlement pollen records (250 – 500 cal BP) from the Neotoma Paleoecology Database and calculated the ratio of Ambrosia to Artemisia in each EPA Level III ecoregion of the North American midcontinent which borders the Great Plains. We show that the ratio of Ambrosia to Artemisia pollen successfully distinguishes between ecoregions at regional to subcontinental scales in both surface pollen and modern pre-European settlement pollen across the North American midcontinent. The Ambrosia to Artemisia ratio can be used to improve delineations of past ecoregion boundaries and aid in distinguishing between vegetation types.


1 - Iowa State University, Ecology, Evolution, and Organismal Biology, 2200 Osborn Dr, 251 Bessey Hall, Ames, Iowa, 50011, United States
2 - Iowa State University, Geological and Atmospheric Sciences, 2237 Osborn Dr , 151 Science, Ames, Iowa, 50011, United States
3 - Iowa State University, Department Of Ecology, Evolution, And Organismal Biology, 251 Bessey Hall, 2200 Osborn Dr., Ames, IA, 50011, United States

Keywords:
Paleoecology
prairie
ecotone
ecoregion
paleoclimate.

Presentation Type: Oral Paper
Number: 0005
Abstract ID:974
Candidate for Awards:Isabel Cookson Award


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