Canopy greenness, atmospheric aridity, and large rain events jointly regulate evapotranspiration partitioning in a temperate semiarid shrubland

Hao, Shaorong; Jia, Xin; Mu, Yanmei; Zha, Tianshan; Qin, Shugao; Liu, Peng; Tian, Yun; Qi, Jiandong; Zhao, Hongxian; Li, Xinhao

doi:10.1016/j.agrformet.2023.109425

Cited by 9 publications

(10 citation statements)

References 66 publications

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“…However, the value reported here was low compared to that reported for spruce forests in Russia (i.e., 0.80; Liu P. et al, 2022;Liu Y. J. et al, 2022). These comparisons suggest that differences in site conditions, measurement methods, and spatial scales can contribute to minor variations in reported T/ET-values (Scott and Biederman, 2017;Hao et al, 2023). Unlike the first hypothesis, long-term trends, even in areas of massive tree mortality, T/ET may be less affected during the transition, disturbance-to-recovery period, as uncovered during the first eight years of our study.…”

Section: Variability In Et and T/etcontrasting

confidence: 74%

“…Adjusting ET (or T/ET) for energy balance closure is controversial (Rungee et al, 2019;Mu et al, 2022) and was, thus, not considered here. Also, an imperfect energy balance closure had negligible influence on the temporal patterns observed in either ET or T/ET (Hao et al, 2023).…”

Section: Flux and Hydrometeorological Measurementsmentioning

confidence: 94%

“…Energy inputs usually constrained the variation in ET in highlatitudinal regions of the world (Launiainen, 2010). Atmospheric drought, soil water availability, and precipitation were the principal factors affecting variations in T/ET in shrub-, grass-, and woodlands, where water shortages are more likely to occur (Scott et al, 2021;Hao et al, 2023). Canopy characteristics, i.e., canopy structure and amount of functional leaf area, are also responsible for a share of the observed seasonal and interannual variations in ET and T/ET in undisturbed ecosystems (Zhou et al, 2016;Mu et al, 2022;Hao et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

“…Atmospheric drought, soil water availability, and precipitation were the principal factors affecting variations in T/ET in shrub-, grass-, and woodlands, where water shortages are more likely to occur (Scott et al, 2021;Hao et al, 2023). Canopy characteristics, i.e., canopy structure and amount of functional leaf area, are also responsible for a share of the observed seasonal and interannual variations in ET and T/ET in undisturbed ecosystems (Zhou et al, 2016;Mu et al, 2022;Hao et al, 2023). However, prior studies of disturbed sites have attributed year-to-year variations in water vapor fluxes to forest-related factors, including canopy greenness (Jin et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Evapotranspiration and its partitioning during and following a mountain pine beetle infestation of a lodgepole pine stand in the interior of British Columbia, Canada

Hao,

Jia,

Zhao

et al. 2024

Front. For. Glob. Change

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IntroductionMassive tree mortality events in western Canada due to widespread infestation by mountain pine beetle (MPB) are expected to impact local-to-regional evapotranspiration (ET) dynamics during and after a disturbance. How ecosystem-level ET and its components may vary with canopy-tree mortality (treefall) and subsequent understory recovery remains unclear.MethodsWe used 10 years of continuous eddy-covariance and remote-sensing data (2007–2016) and machine-learning models based on random forest and xgboost to determine forest- and climate-driven effects at temporal scales appropriate for a lodgepole pine-dominated stand following a major, five-year MPB disturbance initiated in the summer of 2006.ResultsTotal annual ET over the 10 years ranged from 207.2 to 384.6 mm, with annual plant transpiration (T) contributing to 57 ± 5.4% (mean ± standard deviation) of annual ET. Annual ET initially declined (2007–2011) and then increased (2011–2016), with ET and T/ET increasing at statistically non-significant rates of approximately 3.2 and 1.2% per year from 2007 to 2016. Air temperature (Ta) and vapor pressure deficit (VPD) were the most important predictors of seasonal variation in ET and T/ET during the 10-year period, with high Ta, VPD, and photosynthetically active radiation (PAR) causing ET and T/ET to increase. Annual ET increased with both increasing spring Ta and decreasing VPD. Annual T/ET was shown to increase with increasing VPD and decrease with increasing volumetric soil water content at a 5-cm depth (VWC5). Enhanced vegetation index (EVI, an indicator of canopy greenness) lagged T and overstory tree mortality, whereas previous- and current-year values of EVI were shown to be poor predictors of annual ET and T/ET.Discussion and conclusionsThese findings suggest that the promotion of climate factors on forest ecosystem-level water vapor fluxes may offset reductions promoted by MPB outbreaks. Climate processes affected water vapor fluxes more than biotic factors, like stand greenness, highlighting the need to include climate-regulatory mechanisms in predictive models of ET dynamics during and subsequent to stand disturbance. Climate and forest-greenness effects on water vapor fluxes need to be explored at even longer time scales, e.g., at decadal scales, to capture long-drawn-out trends associated with stand disturbance and its subsequent recovery.

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Section: Variability In Et and T/etcontrasting

confidence: 74%

Section: Flux and Hydrometeorological Measurementsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evapotranspiration and its partitioning during and following a mountain pine beetle infestation of a lodgepole pine stand in the interior of British Columbia, Canada

Hao,

Jia,

Zhao

et al. 2024

Front. For. Glob. Change

Self Cite

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“…Rainfall events in arid and semiarid regions are discontinuous, highly variable, and largely unpredictable with respect to frequency and intensity in total rainfall amount, and they are key determinants of ecological and plant physiological processes ( Sun et al., 2015 ; Dietrich and Kahmen, 2019 ; Iqbal et al., 2021 ). Further, global climate change appears to increase rainfall patterns’ variability, which would has a more significant influence on vegetation’s survival and water use than its annual and seasonal amount ( Hao et al., 2023 ; Ni et al., 2023 ). Accordingly, research has focused on discontinuous rainfall events of varied amounts rather than seasonal or annual precipitation ( Huang and Zhang, 2016 ; Iqbal et al., 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Responses of sap flow density of two shrub species to rainfall classes on the semiarid Loess Plateau of China

Fang,

Lu,

Liu

et al. 2023

Front. Plant Sci.

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IntroductionRainfall events can determine a cascade of plant physiological and ecological processes, and there is considerable interest in the way that rainfall modifies plant water flux dynamics.MethodsThe sap flow density (SF) of the planted species of Vitex negundo and Hippophae rhamnoides, on the Loess Plateau of China was monitored using the heat balance method from 2015 to 2017.Results and discussionThe results showed that SF responded differently to rainfall classes because of the changing meteorological and soil water content (SWC) conditions. For class 1: 0.2–2 mm, SF increased by 14.36–42.93% for the two species, which were mainly attributable to the effect of solar radiation and vapor pressure deficit after rainfall. For class 2: 2–10 mm, SF remained nearly stable for V. negundo and decreased for H. rhamnoides because of the relative humidity’s effect. For class 3: > 10 mm, SF increased significantly because of increased SWC and the increasing response to solar radiation. The increased percentage of SF was relatively higher for V. negundo when rainfall was less than 20 mm, while the value was higher for H. rhamnoides when rainfall was greater than 10 mm. Further, V. negundo’s water potential increased at the soil–root interface (ψ0) and ψL, indicating that the plant, which has shallower roots and a coarser of leaf and bark texture, considered as anisohydric species and used precipitation-derived upper soil water to survive. The relatively consistent ψL and ψ0 for H. rhamnoides, which has deep roots and leathery leaves, indicated that this species was considered as isohydric species and insensitive to the slight change in the soil water status. The differed response patter and water use strategies between the two species showed that species as V. negundo are more susceptible to frequent, but small rainfall events, while larger, but less frequent rainfall events benefit such species as H. rhamnoides. This study quantified the effect of environmental factors for SF variation. The results could help formulate a selection process to determine which species are more suitable for sustainable management in the afforestation activities under the context of more frequent and intense rainfall events.

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Stronger control of surface conductance by soil water content than vapor pressure deficit regulates evapotranspiration in an urban forest in Beijing, 2012–2022

Li,

Zha,

Black

et al. 2024

Agricultural and Forest Meteorology

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Canopy greenness, atmospheric aridity, and large rain events jointly regulate evapotranspiration partitioning in a temperate semiarid shrubland

Cited by 9 publications

References 66 publications

Evapotranspiration and its partitioning during and following a mountain pine beetle infestation of a lodgepole pine stand in the interior of British Columbia, Canada

Evapotranspiration and its partitioning during and following a mountain pine beetle infestation of a lodgepole pine stand in the interior of British Columbia, Canada

Responses of sap flow density of two shrub species to rainfall classes on the semiarid Loess Plateau of China

Stronger control of surface conductance by soil water content than vapor pressure deficit regulates evapotranspiration in an urban forest in Beijing, 2012–2022

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