Topographic controls on spatial patterns of conifer transpiration and net primary productivity under climate warming in mountain ecosystems
Article first published online: 7 OCT 2009
Copyright © 2009 John Wiley & Sons, Ltd.
Volume 2, Issue 4, pages 541–554, December 2009
How to Cite
Tague, C., Heyn, K. and Christensen, L. (2009), Topographic controls on spatial patterns of conifer transpiration and net primary productivity under climate warming in mountain ecosystems. Ecohydrol., 2: 541–554. doi: 10.1002/eco.88
- Issue published online: 26 NOV 2009
- Article first published online: 7 OCT 2009
- Manuscript Accepted: 27 JUL 2009
- Manuscript Received: 12 DEC 2008
- alpine ecosystems;
- net primary productivity;
- climate change;
- hydrologic modelling;
- Sierra Nevada
The response of forests to a warmer climate depends upon the direct impacts of temperature on forest ecophysiology and indirect effects related to a range of biogeophysical processes. In alpine regions, reduced snow accumulation and earlier melt of seasonal snowpacks are expected hydrologic consequences of warming. For forests, this leads to earlier soil moisture recharge, and may increase summer drought stress. At the same time, increased air temperature alters plant net primary productivity. Most models of climate change impacts focus either on hydrologic behaviour or ecosystem structure or function. In this study we address the interactions between them. We use a coupled model of eco-hydrologic processes to estimate changes in evapotranspiration and vegetation productivity under temperature warming scenarios. Results from Yosemite National Park, in the California Sierra Nevada, suggest that for most snow-dominated elevations, the shift in the timing of recharge is likely to lead to declines in productivity and vegetation water use, even with increased water-use efficiency associated with elevated atmospheric CO2 concentrations. The strength of this effect, however, depends upon interactions between several factors that vary substantially across elevation gradients, including the initial timing of melt relative to the summer growing season, vegetation growth, and the extent to which initial vegetation is water-limited or temperature-limited. These climate-driven changes in vegetation water use also have important implications for summer streamflow. Results from this analysis provide a framework that can be used to develop strategic measurement campaigns and to extrapolate from local measurements of vegetation responses to watershed scale patterns. Copyright © 2009 John Wiley & Sons, Ltd.