Print PageShifts in plant phenology provide some of the strongest evidence for climate change, a signal that is consistent across both local and regional scales. Since temperature strongly influences the trajectory of vegetation dynamics through its impact on snow melt, patterns of vegetation growth serve to integrate such climatic data. In mountainous areas such as Yellowstone, snowmelt triggers the onset of spring and consequent dynamics of the growing season. Annual migration across the landscape in response to vegetation green up is a well-documented strategy among northern hemisphere ungulates and the fat stores acquired during this period are critical to overwinter survival, reproduction, and population dynamics. In order to understand the critical linkages between climate, vegetation, elk and wolves, we modeled how climate induced changes in temperature interact with the landscape characteristic to impact spatial and temporal patterns of grass phenology across the Greater Yellowstone Ecosystem (GYE). Using satellite derived vegetation data from 2000-2010 for the summer and winter range of the northern elk herd we tested several hypotheses to understand the impact of temperature on dynamics of summer green-up.
Results/Conclusions
We find that, under warmer conditions, the green wave progressed significantly faster, with high quality forage occurring at higher elevations compared to cool years. We also find that temperature influenced the spatial synchrony in the rate of green up among neighboring locations although the strength of this response was strongly influenced by landscape features. We also discuss consequences for changing green wave conditions for elk migration between the summer and winter range.
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