Influence of evaporation from the forest floor on evapotranspiration from the dry canopy

Daikoku, Kenichi; Hattori, Satoshi; Deguchi, Aiko; Aoki, Yu; Miyashita, Mari; Matsumoto, Kazuho; Akiyama, Junichi; Iida, S.; Toba, Tae; Fujita, Yuji; Ohta, Takeshi

doi:10.1002/hyp.7010

Cited by 30 publications

(20 citation statements)

References 58 publications

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“…Daikoku et al . () also reported that the seasonal variation in E soil measured by a closed chamber system was related strongly to D more than to available energy above the canopy in a broad‐leaved forest. Contributions of both D and R s to E soil in this study might be associated with the closed canopy of the KEW (LAI = 4.5–5.5), which may cause inhibition of mixing of air beneath the canopy by wind.…”

Section: Discussionmentioning

confidence: 99%

Inter‐annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Tsuruta

Kosugi

Takanashi

et al. 2016

Hydrological Processes

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This study was undertaken to evaluate the effects of climatic variability on inter‐annual variations in each component of evapotranspiration (ET) and the total ET in a temperate coniferous forest in Japan. We conducted eddy covariance flux and meteorological measurements for 7 years and parameterized a one‐dimensional multi‐layer biosphere‐atmosphere model (Kosugi et al., ) that partitions ET to transpiration (Tr), wet‐canopy evaporation (Ewet), and soil evaporation (Esoil). The model was validated with the observed flux data. Using the model, the components of ET were estimated for the 7 years. Annual precipitation, ET, Tr, Ewet, and Esoil over the 7 years were 1536 ± 334 mm, 752 ± 29 mm, 425 ± 37 mm, 219 ± 34 mm, and 108 ± 10 mm, respectively. The maximum inter‐annual fluctuation of observed ET was 64 mm with a coefficient of variance (CV) of 2.7%, in contrast to relatively large year‐to‐year variations in annual rainfall (CV = 20.1%). Tr was related to the vapour pressure deficit, incoming radiation, and air temperature with relatively small inter‐annual variations (CV = 8.2%). Esoil (CV = 8.6%) was related mainly to the vapour pressure deficit. Ewet was related to precipitation with large inter‐annual variations (CV = 14.3%) because of the variability in precipitation. The variations in Ewet were counterbalanced by the variations in Tr and Esoil, producing the small inter‐annual variations in total ET. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

Inter‐annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Tsuruta

Kosugi

Takanashi

et al. 2016

Hydrological Processes

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“…Forest floor evaporation. The E f was measured with three weighing lysimeters placed randomly in the study site (Kelliher et al, 1990;Schaap and Bouten, 1997;Daikoku et al, 2008). The lysimeter was a container of 0.2-m diameter filled with forest soil that was disturbed as little as possible.…”

Section: Measurementsmentioning

confidence: 99%

Partitioning of the total evapotranspiration in a Japanese cypress plantation during the growing season

et al. 2013

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We investigated the contribution of three evapotranspiration (ET) components including canopy interception (Ei), tree transpiration (Et) and forest floor evaporation (Ef) and identified the sources depth of evaporated water in a Japanese cypress stand. Monitoring primarily focused on the growing season of July–October 2011. In a 12 × 13 m plot with 28 trees with a DBH of 19.1 ± 3.9 cm, Ei was calculated as the difference between precipitation on an open field and precipitation under a canopy as the sum of throughfall and stemflow, and Et was measured using the Granier method. Ef was measured by weighing lysimeters. Total ET during the monitoring period was 446.3 mm, accounting for 47.5% of the total precipitation of 938.8 mm. Ei was the dominant evaporation flux and accounted for 53.6% of ET or 25.5% of rainfall, followed by Et with 33.7% of ET or 16.0% of rainfall. The average Et was 1.5 ± 0.6 mm d−1. It was well correlated with soil moisture at a depth of 5–15 cm, which reflected the forest properties, i.e. tree roots were exposed on the forest floor. Ef accounted for 12.7% of ET or 6.0% of rainfall with a daily mean of 0.55 ± 0.26 mm d−1, and was best correlated with soil moisture in the upper 5 cm of soil. These results can improve the understanding of water budget in forested watershed and also be used to build and validate hydrologic models for water resource managements. Copyright © 2013 John Wiley & Sons, Ltd.

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“…In order to assess responses of bulk canopy conductance to water to changes in soil water content, we estimate canopy conductance directly from the measured latent heat flux when conditions are suitable. We assume that the bulk canopy stomatal conductance to water vapour (expressed on a ground-area basis) can be estimated from the observed latent heat flux under conditions of a dry canopy surface conditions and negligible evaporation from the soil surface (such conditions are common in a Mediterranean climate; Daikoku et al, 2008). Bulk canopy stomatal conductance to water vapour, G c , was then estimated from the measured moisture flux, using simplified form of the Penman-Monteith equation assuming that stomatal and atmospheric transfer occur in series, as:…”

Section: Interpreting Fluxnet Datamentioning

confidence: 99%

Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO<sub>2</sub> and water fluxes through combined in situ measurements and ecosystem modelling

Keenan

García²,

Friend

et al. 2009

Biogeosciences

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Abstract. Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations.Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches.The effectiveness of two models, one a dynamic global vegetation model ("ORCHIDEE"), and the other a forest growth model particularly developed for Mediterranean simulations ("GOTILWA+"), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements.In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO 2 and water fluxes. However, accurate predictions of both CO 2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisCorrespondence to: T. Keenan (t.keenan@creaf.uab.es) ture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates.

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Influence of evaporation from the forest floor on evapotranspiration from the dry canopy

Cited by 30 publications

References 58 publications

Inter‐annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Inter‐annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Partitioning of the total evapotranspiration in a Japanese cypress plantation during the growing season

Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO<sub>2</sub> and water fluxes through combined in situ measurements and ecosystem modelling

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Influence of evaporation from the forest floor on evapotranspiration from the dry canopy

Cited by 30 publications

References 58 publications

Inter‐annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Inter‐annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Partitioning of the total evapotranspiration in a Japanese cypress plantation during the growing season

Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO&lt;sub&gt;2&lt;/sub&gt; and water fluxes through combined in situ measurements and ecosystem modelling

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Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO<sub>2</sub> and water fluxes through combined in situ measurements and ecosystem modelling