期刊
ADVANCES IN WATER RESOURCES
卷 66, 期 -, 页码 32-42出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.advwatres.2014.01.006
关键词
Ecohydrology; Numerical modeling; Optimal leaf conductance; Photosynthesis; Root water uptake; Trees competition
资金
- University of Padova, Italy [WP4]
- US Department of Energy (DOE-BER) Terrestrial Ecosystem Sciences program [11-DE-SC-0006700, DE-SC0006967]
- US Department of Agriculture (USDA) [2011-67003-30222]
- National Science Foundation [NSF-EAR-1344703, NSF-AGS-1102227]
- Binational Agricultural Research and Development Fund [IS-4374-11C]
- European Union - EU
- Nicholas School of the Environment
- Pratt School of Engineering (Duke University, Durham, NC, USA)
- Directorate For Geosciences
- Div Atmospheric & Geospace Sciences [1102227] Funding Source: National Science Foundation
- Division Of Earth Sciences
- Directorate For Geosciences [1344703] Funding Source: National Science Foundation
- U.S. Department of Energy (DOE) [DE-SC0006967] Funding Source: U.S. Department of Energy (DOE)
Competition for water among multiple tree rooting systems is investigated using a soil-plant model that accounts for soil moisture dynamics and root water uptake (RWU), whole plant transpiration, and leaf-level photosynthesis. The model is based on a numerical solution to the 3D Richards equation modified to account for a 3D RWU, trunk xylem, and stomatal conductances. The stomatal conductance is determined by combining a conventional biochemical demand formulation for photosynthesis with an optimization hypothesis that selects stomatal aperture so as to maximize carbon gain for a given water loss. Model results compare well with measurements of soil moisture throughout the rooting zone, of total sap flow in the trunk xylem, as well as of leaf water potential collected in a Loblolly pine forest. The model is then used to diagnose plant responses to water stress in the presence of competing rooting systems. Unsurprisingly, the overlap between rooting zones is shown to enhance soil drying. However, the 3D spatial model yielded transpiration-bulk root-zone soil moisture relations that do not deviate appreciably from their proto-typical form commonly assumed in lumped eco-hydrological models. The increased overlap among rooting systems primarily alters the timing at which the point of incipient soil moisture stress is reached by the entire soil-plant system. (C) 2014 Elsevier Ltd. All rights reserved.
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