Modeling hydraulic redistribution and ecosystem response to droughts over the Amazon basin using Community Land Model 4.0 (CLM4)

Hydraulic redistribution is the process of soil water transport through the low‐resistance pathway provided by plant roots. It has been observed in field studies and proposed to be one of the processes that enable the Amazon rainforest to resist periodical dry spells without experiencing water limit...

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Bibliographic Details
Published in:Journal of geophysical research. Biogeosciences 2014-11, Vol.119 (11), p.2130-2143
Main Authors: Yan, Binyan, Dickinson, Robert E.
Format: Article
Language:English
Subjects:
Amazon
CLM
Computational fluid dynamics
Drought
drought response
Droughts
Evapotranspiration
Fluid flow
hydraulic redistribution
Hydraulics
Mathematical models
Moisture content
Parametrization
Plants (organisms)
Rain
Rainforests
Soil water
Vegetation
Water availability
Water transport
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Summary:Hydraulic redistribution is the process of soil water transport through the low‐resistance pathway provided by plant roots. It has been observed in field studies and proposed to be one of the processes that enable the Amazon rainforest to resist periodical dry spells without experiencing water limitations. How and to what extent hydraulic redistribution may increase vegetation resistance to longer or more severe droughts than seasonal dryness have not been investigated yet, which is the focus of this study. The artificially prolonged drought produced by the rainfall exclusion experiment is used as an example of long drought, and the 2005 drought is used as a severe drought. The parameterization of hydraulic redistribution proposed by Ryel et al. (2002) was incorporated into the Community Land Model version 4 (CLM4). Three paired numerical experiments were conducted, one set using the default model (CTL) and the other using the model with considerations of hydraulic redistribution (HR). Results show that the vegetation response (including evapotranspiration, biomass, and leaf area index (LAI)) to dryness of all the three types is better captured with hydraulic redistribution incorporated. Plants are more resistant to dryness when hydraulic redistribution increases plant water availability and thus facilitates their growth. When a drought is long lasting, the vegetation response is delayed by hydraulic redistribution. Therefore, if a drought ends earlier than permanent damage is made, the magnitude of vegetation response will be lowered by this mechanism, i.e., the vegetation will be more resistant to dryness. Key Point Hydraulic redistribution enables plants to resist dryness
ISSN:2169-8953
2169-8961
DOI:10.1002/2014JG002694