Dynamics of evapotranspiration partitioning in a semi-arid forest as affected by temporal rainfall patterns

Raz‐Yaseef, Naama; Yakir, Dan; Schiller, G.; Cohen, Shabtai

doi:10.1016/j.agrformet.2012.01.015

Cited by 172 publications

(113 citation statements)

References 58 publications

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“…S3). A similar pattern was previously reported in forests in water-limited regions (Helman et al, 2017b;Raz-Yaseef et al, 2012;Williams et al, 2012). ET higher than rainwater supply indicates that trees use water stored in deep soil layers during wet years in the subsequent dry years (e.g., 2006 andRaz-Yaseef et al, 2012;Barbeta et al, 2015).…”

Section: Annual-basis Comparisonssupporting

confidence: 66%

“…A similar pattern was previously reported in forests in water-limited regions (Helman et al, 2017b;Raz-Yaseef et al, 2012;Williams et al, 2012). ET higher than rainwater supply indicates that trees use water stored in deep soil layers during wet years in the subsequent dry years (e.g., 2006 andRaz-Yaseef et al, 2012;Barbeta et al, 2015). Thus, the transfer of surplus rainwater from previous years should also be taken into consideration when adjusting the model with available water through the f WA and f WD , which are currently calculated only with the seasonal rainfall.…”

Section: Annual-basis Comparisonsmentioning

confidence: 82%

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A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO<sub>2</sub> uptake in Mediterranean environments

et al. 2017

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Abstract. Estimations of ecosystem-level evapotranspiration (ET) and CO 2 uptake in water-limited environments are scarce and scaling up ground-level measurements is not straightforward. A biophysical approach using remote sensing (RS) and meteorological data (RS-Met) is adjusted to extreme high-energy water-limited Mediterranean ecosystems that suffer from continuous stress conditions to provide daily estimations of ET and CO 2 uptake (measured as gross primary production, GPP) at a spatial resolution of 250 m. The RS-Met was adjusted using a seasonal water deficit factor (f WD ) based on daily rainfall, temperature and radiation data. We validated our adjusted RS-Met with eddy covariance flux measurements using a newly developed mobile lab system and the single active FLUXNET station operating in this region (Yatir pine forest station) at a total of seven forest and non-forest sites across a climatic transect in Israel (280-770 mm yr −1 ). RS-Met was also compared to the satelliteborne MODIS-based ET and GPP products (MOD16 and MOD17, respectively) at these sites.Results show that the inclusion of the f WD significantly improved the model, with R = 0.64-0.91 for the ET-adjusted model (compared to 0.05-0.80 for the unadjusted model) and R = 0.72-0.92 for the adjusted GPP model (compared to R = 0.56-0.90 of the non-adjusted model). The RS-Met (with the f WD ) successfully tracked observed changes in ET and GPP between dry and wet seasons across the sites. ET and GPP estimates from the adjusted RS-Met also agreed well with eddy covariance estimates on an annual timescale at the FLUXNET station of Yatir (266 ± 61 vs. 257 ± 58 mm yr −1 and 765 ± 112 vs.748 ± 124 gC m −2 yr −1 for ET and GPP, respectively). Comparison with MODIS products showed consistently lower estimates from the MODIS-based models, particularly at the forest sites. Using the adjusted RS-Met, we show that afforestation significantly increased the water use efficiency (the ratio of carbon uptake to ET) in this region, with the positive effect decreasing when moving from dry to more humid environments, strengthening the importance of drylands afforestation. This simple yet robust biophysical approach shows promise for reliable ecosystem-level estimations of ET and CO 2 uptake in extreme high-energy waterlimited environments.

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Section: Annual-basis Comparisonssupporting

confidence: 66%

Section: Annual-basis Comparisonsmentioning

confidence: 82%

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO<sub>2</sub> uptake in Mediterranean environments

et al. 2017

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“…After the period of high water availability, the soil began to dry, and both the temperature and air vapor pressure deficit increased, creating conditions that are adverse to gas exchange (D' Ambrosio et al 2006, Mahouachi 2009). Soil water can be retained longer in forests than in agroforests, due to the higher density of plants, lower surface runoff and reduced water loss by evaporation, since less solar radiation can reach the ground (Eastham et al 1988, McDonald et al 2002, Silva et al 2011, Raz-Yaseef et al 2012. It is therefore possible that in SF the higher density of trees and reduced transpiration rates during the dry season were the main responsible factors for the greater soil water content in this system 50 days after the final rainfall, compared to AGP.…”

Section: Discussionmentioning

confidence: 99%

Ecophysiology of deciduous plants grown at different densities in the semiarid region of Brazil

Mendes¹,

Lacerda²,

Fernandes³

et al. 2013

Theor. Exp. Plant Physiol.

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Physiological differences in the Cordia oncocalyx tree growing at different densities in two distinct areas were investigated.An agrosilvopastoral system (AGP) and a secondary forest (SF) were studied. Under both types of land-use, C. oncocalyx presented a relative frequency of approximately 50%, and absolute densities of 670 and 80 individuals per hectare, respectively. Net photosynthesis (A), stomatal conductance (g s ), and transpiration (E) were measured, and the SPAD index was recorded in sun leaves from the canopy and shade leaves from the lower canopy, in both the wet and dry seasons. We quantified the dry biomass of leaves and fruit on a per-tree basis at the end of the wet season. Net photosynthesis was higher in shaded leaves in the AGP in the wet season, reaching an average of 4.8 µmol m -2 s -1 against 3.2 µmol m -2 s -1 under SF. As trees began to shed their leaves at the beginning of the dry season and more radiation reached the shaded leaves, there was an increase in SF for A, depending on the intensity of light reaching the leaves. In the sun leaves, gas exchange was similar for the land-use systems during the wet season, but stronger in AGP than under SF during the dry season. This happened when the leaves in AGP retained more relative water content during a period of low gravimetric levels of the soil water. The lower tree density in AGP promoted a higher SPAD index and dry biomass in both the sun and shaded leaves, and allowed greater A, E and g s rates in the sun leaves at the beginning of the dry period.

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“…The intensified storms have been shown to increase soil water holding by deeper infiltration. This soil water is less susceptible to evaporation, thus the increased storm intensity may increase the water availability for shrub/tree dominated microsites (Raz-Yaseef et al, 2012), but this depends on soil texture and rainfall intensity and needs further investigation for other areas.…”

Section: The Effects At Plot Scalementioning

confidence: 99%

“…At the same time, ET has two distinct components (E and T ), which are controlled by different mechanisms. Partitioning ET is important not only for better understanding the water budget but also in predicting the biogeochemical fluxes driven by hydrological variations (e.g., Wang et al, 2010b;Raz-Yaseef et al, 2012). To efficiently use the limited water resources in drylands, we need to maximize the productive water loss (T ) and minimize the unproductive water loss (E) .…”

Section: Evapotranspiration Partitionmentioning

confidence: 99%

Dryland ecohydrology and climate change: critical issues and technical advances

Wang

D’Odorico

Evans

et al. 2012

Hydrol. Earth Syst. Sci.

261

135

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Abstract. Drylands cover about 40 % of the terrestrial land surface and account for approximately 40 % of global net primary productivity. Water is fundamental to the biophysical processes that sustain ecosystem function and food production, particularly in drylands where a tight coupling exists between ecosystem productivity, surface energy balance, biogeochemical cycles, and water resource availability. Currently, drylands support at least 2 billion people and comprise both natural and managed ecosystems. In this synthesis, we identify some current critical issues in the understanding of dryland systems and discuss how arid and semiarid environments are responding to the changes in climate and land use. The issues range from societal aspects such as rapid population growth, the resulting food and water security, and development issues, to natural aspects such as ecohydrological consequences of bush encroachment and the causes of desertification. To improve current understanding and inform upon the needed research efforts to address these critical issues, we identify some recent technical advances in terms of monitoring dryland water dynamics, water budget and vegetation water use, with a focus on the use of stable isotopes and remote sensing. These technological advances provide new tools that assist in addressing critical issues in dryland ecohydrology under climate change.

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Dynamics of evapotranspiration partitioning in a semi-arid forest as affected by temporal rainfall patterns

Cited by 172 publications

References 58 publications

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO<sub>2</sub> uptake in Mediterranean environments

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO<sub>2</sub> uptake in Mediterranean environments

Ecophysiology of deciduous plants grown at different densities in the semiarid region of Brazil

Dryland ecohydrology and climate change: critical issues and technical advances

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Dynamics of evapotranspiration partitioning in a semi-arid forest as affected by temporal rainfall patterns

Cited by 172 publications

References 58 publications

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO&lt;sub&gt;2&lt;/sub&gt; uptake in Mediterranean environments

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO&lt;sub&gt;2&lt;/sub&gt; uptake in Mediterranean environments

Ecophysiology of deciduous plants grown at different densities in the semiarid region of Brazil

Dryland ecohydrology and climate change: critical issues and technical advances

Contact Info

Product

Resources

About

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO<sub>2</sub> uptake in Mediterranean environments

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO<sub>2</sub> uptake in Mediterranean environments