Nonlinear interactions between climate, landscape structure, and plant migration.
Gray, Stephen*,1, Betancourt, Julio1, Jackson, Stephen2, 1 USGS Desert Laboratory, Tucson, AZ, USA2 University of Wyoming, Laramie, WY, USA
ABSTRACT- Long-duration tree-ring chronologies and other high-resolution proxy archives suggest that the climate of western North America is characterized by highly non-stationary behavior. More specifically, western climate tends to switch between persistent hot/dry and cool/wet regimes over decadal to centennial timescales. When combined with fossil woodrat middens, these records show that persistent climatic regimes paced plant migrations throughout the Holocene via their role in promoting or suppressing disturbances. Moreover, decadal to centennial climate variability modulates the frequency of dispersal events and the distance they cover, as well as probability of a seed reaching a suitable location on the landscape. Switching between different climatic regimes may also alternately increase or decrease the probability of survival and reproduction after arrival in a new habitat. The resulting progression of Holocene plant migrations is often one of "fits and starts" marked by multiple long-distance dispersal events and backfilling rather than a steady wave-like progression. If we hope to predict the outcome of future plant migrations, we must first develop forecast models that can accommodate non-stationary climate and potential nonlinear interactions between habitat structure and climate over landscape to regional scales.
Key words: paleoecology, climate, migrations, nonlinearity
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