Changing forest water yields in response to climate warming: Results from long-term experimental watershed sites across North America
Abstract
Climate warming is projected to affect forest catchment water yields, but effects may vary among biomes. We hypothesized that catchments where water yields have varied relatively little in response to climate warming would be more resilient to warming effects than other types of catchments are. To test this hypothesis, we examined the variability in historical catchment water yields at long-term experimental watershed sites across Canada and the United States. Using the theoretical framework of the Budyko curve, which estimates catchment evaporation as a function of catchment dryness, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation was defined as a catchment's change in actual ET divided by P (AET/P) coincident with a shift from a cool to warm period. Elasticity was defined as the ratio of inter-annual variation in potential ET divided by P (PET/P, the dryness index) to inter-annual variation in actual ET divided by P (AET/P, the evaporative index). Deviation in water yields was related to elasticity. Alpine sites showed greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer sites included catchments with lowest elasticity and had stable to higher water yields, deciduous sites included catchments with intermediate elasticity and had stable to lower water yields, and mixed forests included catchments with highest elasticity and had stable water yields. For all forest types, there was a tendency for elasticity to converge to 1.0 with forest age. Both forest type and age were determinants of elasticity, which leads to resilience of catchment water yields to climate warming.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.H14C..04J
- Keywords:
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- 1803 HYDROLOGY Anthropogenic effects;
- 1860 HYDROLOGY Streamflow;
- 1884 HYDROLOGY Water supply