PJB-2012-82
CANOPY TRANSPIRATION RESPONSE TO ENVIRONMENTAL VARIATIONS IN PLATYCLADUS ORIENTALIS: PROPERTIES AND MODELLING
LEI HAN1,2, KANGNING HE2*, XINGBO HU2 AND DONG ZHANG2
Abstract
Regrowth of tall, dense forests consumes more water, with the result that catchment yield may decline and even soil desiccation occurred especially in the semi-arid Loess Plateau of China. In this study, meteorological measurements combined with sap flow techniques provided a low-cost option to study the rates of water uptake by individual trees of Platycladus orientalis response to environmental factors on a continuous basis. A series of environmental control functions: vapour pressure deficit, solar radiation and air temperature were used to characterize canopy transpiration (Ec). A Jarvis-type model, modified to directly estimate the Ec rather than canopy conductance, explained 89% of the variation observed in Ec. Cross validation shows that this model provided good predictions of canopy transpiration for P. orientalis. Such a methodology offers a reasonable estimation of water use in the determination of water balance for land water resources planning, vegetation management and impact assessments of rehabilitation.
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