A review of whole-plant water use studies in tree

Abstract

Weighing lysimeters, large-tree potometers, ventilated chambers, radioisotopes, stable isotopes and an array of heat balance/heat dissipation methods have been used to provide quantitative estimates of whole-tree water use. A survey of 52 studies conducted since 1970 indicated that rates of water use ranged from 10 kg day(-1) for trees in a 32-year-old plantation of Quercus petraea L. ex Liebl. in eastern France to 1,180 kg day(-1) for an overstory Euperua purpurea Bth. tree growing in the Amazonian rainforest. The studies included in this survey reported whole-tree estimates of water use for 67 species in over 35 genera. Almost 90% of the observations indicated maximum rates of daily water use between 10 and 200 kg day(-1) for trees that averaged 21 m in height. The thermal techniques that made many of these estimates possible have gained widespread acceptance, and energy-balance, heat dissipation and heat-pulse systems are now routinely used with leaf-level measurements to investigate the relative importance of stomatal and boundary layer conductances in controlling canopy transpiration, whole-tree hydraulic conductance, coordinated control of whole-plant water transport, movement of water to and from sapwood storage, and whole-plant vulnerability of water transport to xylem cavitation. Techniques for estimating whole-tree water use complement existing approaches to calculating catchment water balance and provide the forest hydrologist with another tool for managing water resources. Energy-balance, heat dissipation and heat-pulse methods can be used to compare transpiration in different parts of a watershed or between adjacent trees, or to assess the contribution of transpiration from overstory and understory trees. Such studies often require that rates of water use be extrapolated from individual trees to that of stands and plantations. The ultimate success of this extrapolation depends in part on whether data covering short time sequences can be applied to longer periods of time. We conclude that techniques for estimating whole-tree water use have provided valuable tools for conducting basic and applied research. Future studies that emphasize the use of these techniques by both tree physiologists and forest hydrologists should be encouraged.

Multiscale remote-sensing retrieval in the evapotranspiration of Haloxylon ammodendron in the Gurbantunggut desert, China

“…At the plant scale, various measurement methods, including weighing lysimeters, ventilated chambers, radioisotopes, stable isotopes and heat balance/heat dissipation methods have been proven to be valuable tools for conducting basic and applied research (Wullschleger et al 1998). Sap flow instruments, the effective techniques to measure plant transpiration (Hatton et al 1995;Vertessy et al 1997), have been used to study the transpiration of Haloxylon ammodendron and Tamarix ramosissima in Taklimakan desert (Xu 2006;Xu et al 2008).…”

Axial and radial water transport and internal water storage in tropical forest canopy trees

“…Wullschleger et al 1998). Because sap flow is typically measured over a relatively narrow range of sapwood depth, usually close to the vascular cambium where flow is often, but not always, near maximal, the reliability of scaling from these measurements to whole-tree water use is constrained by uncertainty about radial profiles of sap flow, particularly in large trees with deep sapwood.…”

Fluxo de seiva xilemática em mamoeiro 'Golden' cultivado por microaspersão sobre copa: relações com as variáveis ambientais

“…Ainda, nesta figura, observam-se valores elevados de FS, em quantidades de radiação global bem baixas ou quase nulas. Tais respostas podem ser explicadas por meio da defasagem entre a transpiração do dossel (Dados não mostrados) e a resposta da temperatura nos sensores instalados na base do tronco do mamoeiro (Fase lag) (ZHANG et al, 1997;WULLSCHLEGER et al, 1998). Logo pela manhã, têm-se valores elevados de radiação global, sem haver sensibilidade na região das sondas.…”

“…Quando se efetuam determinações do movimento de água no tronco de plantas de menor porte, este é equivalente à transpiração do dossel (WULLSCHLEGER et al, 1998). Entretanto, em árvores, existe uma defasagem, ou seja, pode haver uma transpiração do dossel sem haver um imediato movimento de água no tronco (SCHULZE et al, 1985;PHILLIPS et al, 1997).…”