期刊
ADVANCES IN WATER RESOURCES
卷 60, 期 -, 页码 110-120出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.advwatres.2013.07.008
关键词
Hydraulic lift; Root water uptake; Soil moisture; Stomatal conductance; Transpiration
资金
- National Science Foundation [NSF EAR-1013339, NSF-AGS-110227]
- United States Department of Agriculture [2011-67003-30222]
- United States Department of Energy (DOE) through the Office of Biological and Environmental Research (BER) - the Terrestrial Ecosystem Science (TES) program [DE-SC0006967]
- Binational Agricultural Research and Development (BARD) Fund [IS-4374-11C]
- University of Padova
- European Commission [FP7-ENV-2009-1- 244151]
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [1102227] Funding Source: National Science Foundation
- Division Of Earth Sciences
- Directorate For Geosciences [1013339] Funding Source: National Science Foundation
Understanding photosynthesis and plant water management as a coupled process remains an open scientific problem. Current eco-hydrologic models characteristically describe plant photosynthetic and hydraulic processes through ad hoc empirical parameterizations with no explicit accounting for the main pathways over which carbon and water uptake interact. Here, a soil-plant-atmosphere continuum model is proposed that mechanistically couples photosynthesis and transpiration rates, including the main leaf physiological controls exerted by stomata. The proposed approach links the soil-to-leaf hydraulic transport to stomatal regulation, and closes the coupled photosynthesis-transpiration problem by maximizing leaf carbon gain subject to a water loss constraint. The approach is evaluated against field data from a grass site and is shown to reproduce the main features of soil moisture dynamics and hydraulic redistribution. In particular, it is shown that the differential soil drying produced by diurnal root water uptake drives a significant upward redistribution of moisture both through a conventional Darcian flow and through the root system, consistent with observations. In a numerical soil drying experiment, it is demonstrated that more than 50% of diurnal transpiration is supplied by nocturnal upward water redistribution, and some 12% is provided directly through root hydraulic redistribution. For a prescribed leaf area density, the model is then used to diagnose how elevated atmospheric CO2 concentration and increased air temperature jointly impact soil moisture, transpiration, photosynthesis, and whole-plant water use efficiency, along with compensatory mechanisms such as hydraulic lift using several canonical forms of root-density distribution. (C) 2013 Elsevier Ltd. All rights reserved.
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