Physiology on a Landscape Scale: Plant-Animal Interactions1

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Physiology on a Landscape Scale: Plant-Animal Interactions
From  WARREN P. PORTER,2* JOHN L. SABO,3† CHRISTOPHER R. TRACY,* O. J. REICHMAN,† AND NAVIN RAMANKUTTY‡
SYNOPSIS. We explore in this paper how animals can be affected by variation in climate, topography,
vegetation characteristics, and body size. We utilize new spatially explicit state-of-the-art models that incorporate
principles from heat and mass transfer engineering, physiology, morphology, and behavior that have
been modified to provide spatially explicit hypotheses using GIS. We demonstrate how temporal and spatial
changes in microclimate resulting from differences in topography and vegetation cover alter animal energetics,
and behavior. We explore the impacts of these energetic predictions on elk energetics in burned and
unburned stands of conifer in winter in Yellowstone National Park, chuckwalla lizard distribution limits in
North America, California Beechey Ground squirrel and Dusky Footed woodrat mass and energy requirements
and activity patterns on the landscape, their predator prey interactions with a rattlesnake, Crotalus
viridis, and shifts in that food web structure due to topographic and vegetative variation. We illustrate how
different scales of data/observation provide different pieces of information that may collectively define the
real distributions of a species. We then use sensitivity analyses of energetic models to evaluate hypotheses
about the effects of changes in core temperature (fever) global climate (increased air temperature under a
global warming scenario) and vegetation cover (deforestation) on winter survival of elk, the geographic
distribution of chuckwallas and the activity overlap of predator and prey species within a subset of commonly
observed species in a terrestrial food web. Variation in slope and aspect affect the spatial variance
in solar radiation incident on the ground, hence ground surface temperature, at the same elevation, same
hourly 2 m air temperatures, and wind speeds. We illustrate visually how spatial effects and landscape
heterogeneity make statistical descriptions of animal responses problematic, since multiple distributions of
their responses to climate, topography, and vegetation on the landscape can yield the same descriptive
statistics, especially at high (30 m) resolution. This preliminary analysis suggests that the model has farreaching
implications for hypothesis testing in ecology at a variety of spatial and temporal scales