Analytical approach to relate evapotranspiration, canopyatmosphere coupling level, and water deficit sensitivity

Martínez-Maldonado, Fabio Ernesto; Marin, Fábio Ricardo

doi:10.1590/1678-4499.20220198

Cited by 2 publications

(3 citation statements)

References 31 publications

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“…Previous studies have shown that as Ω decreased, the linear regression correlation between g a and g c increased, indicating a stronger coupling effect between the canopy and atmosphere (Jiao et al, 2018; Zhang et al, 2016). Ω is a vital signal to evaluate the coupling degree between canopy and atmosphere, and the closer Ω is to 0, the more sensitive stomatal behaviour is to atmospheric environmental factors (Maldonado & Marin, 2023). Smaller decoupling coefficients indicate that transpiration rates are more influenced by VPD than R n , while larger Ω suggests the opposite (Fu et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Variation in canopy conductance of Cunninghamia lanceolata forest and its response to environmental factors after an extreme rainfall event

Xing,

Cheng,

Yang

et al. 2024

Hydrological Processes

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Canopy conductance (gc) is a crucial parameter in simulating evapotranspiration and modulating water exchange, but its variation mechanism has regional uncertainties and complex environmental co‐controls. In addition, the effect of extreme rainfall on gc cannot be ignored under the changing climate. Here, we investigated the variation and environmental controls on gc and the effect of extreme rainfall events in a Cunninghamia lanceolata forest across the subtropical area of Southern China. In July 2020, an extreme rainstorm hit the source area of the Xin'an River, with the cumulative rainfall on July 7 and 8 reaching 216.6 mm. The thermal diffusion probe method was used to measure the density of sap flow, and the environmental factors such as air temperature (Ta), net solar radiation (Rn) and soil water content (SWC) were monitored during the growing seasons of 2020 and 2021. Ultimately, gc obtained by the Penman‐Monteith equation was adopted since the result from the Köstner equation was overestimated. gc showed a unimodal curve on the diurnal scale, and this characteristic was more obvious after the extreme rainfall. Daily gc appeared a fluctuating pattern with a maximum in summer. gc was simultaneously affected by Ta, Rn, water vapour pressure difference (VPD), SWC, among which Ta was the most significant driving factor at both the diurnal and daily timescales. The regulation of Ta, VPD and SWC on gc had obvious thresholds, and the most definite response mode was VPD (2020: 1.25 kPa; 2021: 0.95 kPa). SWC and Ta were the dominant factors after the rainfall period, and the promotion effect of VPD on post‐rainy days turned to inhibition effect on typical sunny days. These findings will further reveal the water exchange mechanism between atmosphere and vegetation and impacts of environmental factors in subtropical coniferous forests, especially after the extreme rainfall events.

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Section: Discussionmentioning

confidence: 99%

Variation in canopy conductance of Cunninghamia lanceolata forest and its response to environmental factors after an extreme rainfall event

Xing,

Cheng,

Yang

et al. 2024

Hydrological Processes

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“…The lowest values (omega ~ 0.6) were also observed mainly in the vegetative and tuber bulking stages. These lower Ω values are indicative that ET and GPP were mainly controlled by VPD and Rc (Aires et al, 2008;Jarvis and Mcnaughton, 1986;Martinez Maldonado and Marin, 2023;Nassif et al, 2014) under rainfed conditions of the RF site. Both omega and the correlation coefficient (r) had a similar trend of variation along crop growth.…”

Section: Et-gpp Coupling and The Omega Rolementioning

confidence: 94%

“…The high Ra between leaf surfaces and the air above the canopy indicates a lower diffusivity of water vapor from the leaves that makes ET more strongly controlled by incoming radiation and less dependent on stomatal conductance and canopy resistance (Jarvis, 1985;Jarvis and Mcnaughton, 1986;McNaughton and Jarvis, 1991;Steduto and Hsiao, 1998;Sutherlin et al, 2019a;Zhang et al, 2016). This omega Ω→1 gives to potato canopy a greater advantage because the transpiration is not affected by the stomatal conductance and the water fluctuations in the soil (Sutherlin et al 2019b;Martinez Maldonado and Marin 2023). As a result of tightly coupled carbon and water fluxes, and no canopy resistance restrictions for fluxes potato ecosystem became more efficient in increasing its capacity to optimize carbon gains to water losses as the crop growth progressed (Katul et al 2010b), a situation observed in the daily pattern of IWUE being strongly influenced by the LAI and the growth stages (Beer et al 2009).…”

Section: Et-gpp Coupling and The Omega Rolementioning

confidence: 99%

Carbon and water vapor exchanges coupling in irrigated and rainfed Andean potato (Solanum tuberosum subsp. andigenum) agroecosystems

Martínez-Maldonado,

Castaño-Marín,

Góez-Vinasco

et al. 2023

Preprint

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We studied the response of net ecosystem carbon exchange (NEE) to water availability conditions by detailing the dynamics of H2O and CO2 exchanges between the canopy and atmosphere of three different potato water regimes cropping systems [full irrigation (FI), deficit irrigation (DI) and rainfed (RF)]. Through the eddy covariance method, we measured carbon and water fluxes and determined the inherent water use efficiency (IWUE) as a conceptual frame for comparing diurnal cycles of carbon and water and quantifying their coupling/decoupling degree. Surface resistances and the omega (Ω) factor were computed to know the degree of canopy control over carbon and water fluxes. Additionally, leaf area index (LAI) and specific leaf area (SLA) were measured over the cropping systems. The highest sink activity at the FI site (NEE= −311.96 ± 12.82 g C m−2) was due to the larger canopy, with high autotrophic activity and low internal resistance which supported a highly coupled and synchronized ET – GPP exchange represented in the higher IWUE (4.7 mg C kPa s-1 kg-1 H2O). The lower sink capacity at the DI site (NEE= −17.3 ± 4.6 g C m−2) and the net carbon source activity from the RF (NEE = 187.21 ± 3.84 g C m−2) are consequences of a smaller area for water and carbon exchange, and a low IWUE (2.3 and 1.01 mg C kPa s-1 kg-1 H2O, respectively) from decoupled and desynchronized carbon and water exchange caused by unbalanced restrictions on ET and GPP fluxes.

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Analytical approach to relate evapotranspiration, canopyatmosphere coupling level, and water deficit sensitivity

Cited by 2 publications

References 31 publications

Variation in canopy conductance of Cunninghamia lanceolata forest and its response to environmental factors after an extreme rainfall event

Variation in canopy conductance of Cunninghamia lanceolata forest and its response to environmental factors after an extreme rainfall event

Carbon and water vapor exchanges coupling in irrigated and rainfed Andean potato (Solanum tuberosum subsp. andigenum) agroecosystems

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