Montane conifer water use under more episodic and earlier snowmelt
Abstract
Snowmelt is a major source for soil water storage that supplies water for summer tree water use in the Mediterranean climate of the Sierra Nevada, California. Inter-annual differences in climate combined with topography (e.g. elevation, slope, and aspect) control the timing and amount of snow water inputs. Yet, few studies have explored how differences in the timing and magnitude of snowmelt affect tree water use in Mediterranean conifer forests. Here we combined sap flux, meteorological, and hydrological measurements on north and south aspects in the Sagehen Creek catchment (Sierra Nevada) to investigate the controls on how the timing of tree water use responds to the timing and magnitude of snowmelt. We found that tree water use prior to its seasonal peak in July was largely controlled by air temperature, and that cool and cloudy conditions during spring reduced tree water use at both north and south aspects. After its seasonal peak, tree water use was largely limited by soil moisture. In years with earlier snow disappearance, reductions in shallow soil moisture indicated an earlier peak of tree water use. Moreover, years with earlier snow disappearance had a greater number of days of tree water stress (i.e. days with soil moisture limitations) prior to minimum sap flux values typically reached in late September and October. Overall, our results suggest that earlier snowmelt will shift peaks of tree water use towards earlier in the growing season and increase the number of water-stressed days. Our results have applications in the use of land surface models to project future changes in montane conifer water use and in the management of forest and water resources in a warmer world.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H13H..02C
- Keywords:
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- 0740 Snowmelt;
- CRYOSPHERE;
- 1621 Cryospheric change;
- GLOBAL CHANGE;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1817 Extreme events;
- HYDROLOGY