A review of approaches for evapotranspiration partitioning

Kool, Dilia; Agam, Nurit; Lazarovitch, Naftali; Heitman, Joshua L.; Sauer, Thomas J.; Ben‐Gal, Alon

doi:10.1016/j.agrformet.2013.09.003

Cited by 627 publications

(428 citation statements)

References 159 publications

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“…Then canopy transpiration could be determined by the difference of vapor exchange rate between the CK and DS plots. Among different partitioning methods (reviewed by Kool et al 2014), our approach should be a more accurate observation method to separate the components of E and T from ecosystem ET as it involves less disturbance of the original environmental conditions and avoids the influence of air advection or large eddies.…”

Section: Flux Measurementsmentioning

confidence: 99%

“…GEP and Re are two of the inherent ecosystem traits that are complexly influenced by various meteorological factors and species characteristics (Hall and Scurlock 1991;Yepez et al 2007). Because of the complex feedbacks between water balance and carbon budget and the difficulty in the accurate dividing of ecosystem mass fluxes (Kool et al 2014), limited attempt has been made to compare different calculation methods in estimating WUE responding to land use differences. Thus, a proper ecosystem mass fluxes divide method will largely prompt our mechanism understanding on WUE regulation process.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of evapotranspiration components and water-use efficiency among different land use patterns of temperate steppe in the Northern China pastoral-farming ecotone

Fan

et al. 2015

Int J Biometeorol

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Water-use efficiency (WUE), which links carbon and water cycles, is an important indicator of assessing the interactions between ecosystems and regional climate. Using chamber methods with and without plant removal treatments, we investigated WUE and evapotranspiration (ET) components in three ecosystems with different land-use types in Northern China pastoral-farming ecotone. In comparison, ET of the ecosystems with grazing exclusion and cultivating was 6.7 and 13.4 % higher than that of the ecosystem with free grazing. The difference in ET was primarily due to the different magnitudes of soil water evaporation (E) rather than canopy transpiration (T). Canopy WUE (WUEc, i.e., the ratio of gross primary productivity to T) at the grazing excluded and cultivated sites was 17 and 36 % higher than that at the grazing site. Ecosystem WUE (WUEnep, i.e., the ratio of net ecosystem productivity to ET) at the cultivated site was 34 and 28 % lower in comparison with grazed and grazing excluded stepped, respectively. The varied leaf area index (LAI) of different land uses was correlated with microclimate and ecosystem vapor/carbon exchange. The LAI changing with land uses should be the primary regulation of grassland WUE. These findings facilitate the mechanistic understanding of carbon-water relationships at canopy and ecosystem levels and projection of the effects of land-use change on regional climate and productivity.

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Section: Flux Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of evapotranspiration components and water-use efficiency among different land use patterns of temperate steppe in the Northern China pastoral-farming ecotone

Fan

et al. 2015

Int J Biometeorol

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“…Shuttleworth-Wallace model (S-W model) is the first model designed for ET partition, which is a physically-based combination model based on Penman-Monteith equation (Shuttleworth and Wallace, 1985). S-W model has also been regarded as an accurate model and the foundation of other ET partition models, which provides a validation for other models (Kool et al, 2014) and has been widely used (Hu et al, 2009;Iritz et al, 2001;Kato et al, 2004), while there have been no attempt in using S-W model to partition ET into its components at forests of China, which occupied an important portion in global forests (FAO, 2010). China has conducted eddy covariance measurements since 2003 at three forests along the north-south transect of Eastern China (NSTEC), which experiences apparent decreasing temperature and precipitation gradients with the increasing latitude .…”

Section: Introductionmentioning

confidence: 99%

“…Evapotranspiration (ET) of forest, an important component sustaining the forest water and energy balance , affects the global energy partition and then climate, whereas ET is comprised by multiple source water vapor fluxes such as evaporation from soil surface (E), transpiration by plant (T) and evaporation from the intercepted water by canopy (EI) (Kool et al, 2014), which are controlled by different biotic and physical processes (Scanlon and Kustas, 2012). Therefore, to fully clarify the role of each process in Yu et al (2013).…”

Section: Introductionmentioning

confidence: 99%

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Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Zhu

et al. 2015

Ecological Indicators

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The ratio of transpiration to evapotranspiration (T/ET) Forest a b s t r a c t Evapotranspiration (ET), which is comprised by evaporation from soil surface (E), transpiration (T) and evaporation from the intercepted water by canopy (EI), plays an important role in maintaining global energy balance and regulating climate. Quantifying the spatiotemporal variations of T/ET (the ratio of T to ET) can improve our understandings on the role of vegetation ecophysiological processes in climate regulation. Using eddy covariance measurements at three forest ecosystems (Changbaishan temperate broad-leaved Korean pine mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ) and Dinghushan subtropical evergreen mixed forest (DHS)) in north-south transect of Eastern China (NSTEC), we run the revised Shuttleworth-Wallace model (S-W model), validated its performance with the water vapor fluxes measured at two layers, and quantified the spatiotemporal variations of T/ET. The S-W model performed well in simulating ET and T/ET. The mean value of annual T/ET at three forests during the observation period all exceeded 0.6. The diurnal variation of canopy stomal conductance (G c ) dominated that of T/ET. The seasonal dynamics of T/ET was mainly shaped by that of leaf area index (LAI), vapor pressure deficit (VPD) and air temperature (T a ) through altering G c and the portion that the energy absorbed by canopy (P EC ) at temperate forest (CBS), while the seasonal dynamics of T/ET at subtropical forests (QYZ and DHS) were mainly affected by T a , net radiation, VPD, and soil water content through altering G c and soil surface conductance (G s ). The variation of mean annual G c governed the interannual varaition and spatial variation of T/ET. Therefore, forests in Eastern China played an important role in regulating climate through T and G c primarily affected the spatial and temproal variations of the role of forest T in regulating climate.

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Accounting for vegetation height and wind direction to correct eddy covariance measurements of energy fluxes over hilly crop fields

et al. 2015

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As agricultural hilly watersheds are widespread throughout the world, there is a strong need for reliable estimates of land surface fluxes, especially evapotranspiration, over crop fields on hilly slopes. In order to obtain reliable estimates from eddy covariance (EC) measurements in such conditions, the current study aimed at proposing adequate planar fit tilt corrections that account for the combined effects of topography, wind direction, and vegetation height on airflow inclinations. EC measurements were collected within an agricultural hilly watershed in northeastern Tunisia, throughout the growth cycles of cereals, legumes, and pasture. The wind had two dominant directions that induced upslope and downslope winds. For upslope winds, the airflows were parallel to the slopes and slightly came closer to the horizontal plane when vegetation grew. For downslope winds, over fields located in the lee of the rim top, the airflows were almost horizontal over bare soil and came closer to the topographical slope when vegetation grew. We therefore adjusted the planar fit tilt correction on EC measurements according to vegetation height and by discriminating between upslope and downslope winds. This adjusted tilt correction improved the energy balance closure in most cases, and the obtained energy balance closures were similar to that reported in the literature for flat conditions. We conclude that EC data collected within crop fields on hilly slopes can be used for monitoring land surface fluxes, provided planar fit tilt corrections are applied in an appropriate manner.

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A review of approaches for evapotranspiration partitioning

Cited by 627 publications

References 159 publications

Comparison of evapotranspiration components and water-use efficiency among different land use patterns of temperate steppe in the Northern China pastoral-farming ecotone

Comparison of evapotranspiration components and water-use efficiency among different land use patterns of temperate steppe in the Northern China pastoral-farming ecotone

Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Accounting for vegetation height and wind direction to correct eddy covariance measurements of energy fluxes over hilly crop fields

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