Soil water content measurements deliver reliable estimates of water fluxes: A comparative study in a beech and a spruce stand in the Tharandt forest (Saxony, Germany)

Schwärzel, Kai; Menzer, Alexander; Clausnitzer, Falko; Spank, Uwe; Häntzschel, Janet; Grünwald, Thomas; Köstner, Barbara; Bernhofer, Christian; Feger, Karl‐Heinz

doi:10.1016/j.agrformet.2009.07.006

Cited by 68 publications

(67 citation statements)

References 55 publications

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“…Note that we focus in our study on the PET dynamics and that the absolute values could vary depending on the aerodynamic and roughness parameter of different vegetation covers. We further did not partition PET into evaporation and transpiration fluxes, since PET was primarily used as a proxy for potential soil evaporation rates, and evaporation and transpiration usually show a linear relationship in temperate regions (Renner et al, 2016;Schwärzel et al, 2009). To understand the potential atmospheric drivers for the soil water isotopic composition, we investigated the effect of antecedent con-ditions.…”

Section: Discussionmentioning

confidence: 99%

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Sprenger

Tetzlaff

Soulsby

2017

Hydrol. Earth Syst. Sci.

172

165

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Abstract. Understanding the influence of vegetation on water storage and flux in the upper soil is crucial in assessing the consequences of climate and land use change. We sampled the upper 20 cm of podzolic soils at 5 cm intervals in four sites differing in their vegetation (Scots Pine (Pinus sylvestris) and heather (Calluna sp. and Erica Sp)) and aspect. The sites were located within the Bruntland Burn longterm experimental catchment in the Scottish Highlands, a low energy, wet environment. Sampling took place on 11 occasions between September 2015 and September 2016 to capture seasonal variability in isotope dynamics. The pore waters of soil samples were analyzed for their isotopic composition (δ 2 H and δ 18 O) with the direct-equilibration method. Our results show that the soil waters in the top soil are, despite the low potential evaporation rates in such northern latitudes, kinetically fractionated compared to the precipitation input throughout the year. This fractionation signal decreases within the upper 15 cm resulting in the top 5 cm being isotopically differentiated to the soil at 15-20 cm soil depth. There are significant differences in the fractionation signal between soils beneath heather and soils beneath Scots pine, with the latter being more pronounced. But again, this difference diminishes within the upper 15 cm of soil. The enrichment in heavy isotopes in the topsoil follows a seasonal hysteresis pattern, indicating a lag time between the fractionation signal in the soil and the increase/decrease of soil evaporation in spring/autumn. Based on the kinetic enrichment of the soil water isotopes, we estimated the soil evaporation losses to be about 5 and 10 % of the infiltrating water for soils beneath heather and Scots pine, respectively. The high sampling frequency in time (monthly) and depth (5 cm intervals) revealed high temporal and spatial variability of the isotopic composition of soil waters, which can be critical, when using stable isotopes as tracers to assess plant water uptake patterns within the critical zone or applying them to calibrate traceraided hydrological models either at the plot to the catchment scale.

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Section: Discussionmentioning

confidence: 99%

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Sprenger

Tetzlaff

Soulsby

2017

Hydrol. Earth Syst. Sci.

172

165

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“…However, a study of two species (beech and spruce) in the Tharandt forest, Germany showed that soil water shortage led to a significant reduction in the transpiration rate of spruce, but not of beech (Schwärzel et al, 2009). Root distribution reduces the influence of soil water drought on plant transpiration, especially in deep-rooted species that have the ability to access and utilize deep soil water and groundwater overcoming soil drought without any significant changes in transpiration (Prieto et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Responses of shelterbelt stand transpiration to drought and groundwater variations in an arid inland river basin of Northwest China

Shen

Gao

et al. 2015

Journal of Hydrology

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s u m m a r yPlant water use characteristics and transpiration responses under dry conditions are considered essential for effective and sustainable ecosystem management in arid areas. This study was conducted to evaluate the response of shelterbelt stand transpiration to precipitation, soil drought and groundwater variations in an oasis-desert ecotone in the middle of the Heihe River Basin, China. Sap flow was measured in eight Gansu Poplar trees (Populus Gansuensis) with different diameter at breast height over three consecutive growing seasons (2012)(2013)(2014). The groundwater evapotranspiration via plant use was estimated by the White method with diurnal water table fluctuations. The results showed that precipitation increased the stand transpiration but not statistically significant (paired t-test, p > 0.05). The recharge of soil water by irrigation caused stand transpiration acceleration significantly (t-test, p < 0.05). Stand transpiration and canopy conductance increased by 27% and 31%, respectively, when soil water conditions changed from dry to wet. Canopy conductance decreased logarithmically with vapor pressure deficit, while there was no apparent relationship between canopy conductance and solar radiation. The sensitivity of canopy conductance to vapor pressure deficit decreased under dry soil conditions. Groundwater evapotranspiration (0.6-7.1 mm day À1) was linearly correlated with stand transpiration (1.1-6.5 mm day À1 ) (R 2 = 0.71), and these two variables had similar variability. During the drought period, approximately 80% of total stand transpiration came from groundwater evapotranspiration. This study highlighted the critical role of irrigation and groundwater for shelterbelt, and might provide the basis for the development of water requirement schemes for shelterbelt growth in arid inland river basins.

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“…These two techniques give comparable results on shallow soil, but ET EC is usually larger than ET SM on deep soils with the differences accentuated during drought (Wilson et al 2001, Oishi et al 2008). The observed discrepancies were often attributed to the uncertainty in scaling-up of soil moisture measurements within the entire soil profile (Schwarzel et al 2009, Oishi et al 2010, and so we also compared ET SM estimated from the upper soil profile with ET SM estimated from the whole soil profile. The third method, water table fluctuation (ET WT ), is based on water level drawdown due to plant uptake and rebound due to underlying gradients in water head (White 1932).…”

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confidence: 99%

“…Furthermore, to evaluate the effects of periodic drought and better predict the impacts of climate change on ecosystem functions from plantations, it is critical to evaluate the response of each of the hydrologic components (Bond et al 2008. Components of forest water loss may be determined by measuring the simultaneous differences between eddy covariance measurements (ET EC ) and tree sapflow (e.g., Oren et al 1998, Schwarzel et al 2009). These two measures can then be compared with soil water content dynamics (Warren et al 2005) and with soil evaporation (Raz-Yaseef et al 2010a).…”

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confidence: 99%

A Comparison of Three Methods to Estimate Evapotranspiration in Two Contrasting Loblolly Pine Plantations: Age-Related Changes in Water Use and Drought Sensitivity of Evapotranspiration Components

Domec¹,

Sun²,

Noormets³

et al. 2012

Forest Science

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Increasing variability of rainfall patterns requires detailed understanding of the pathways of water loss from ecosystems to optimize carbon uptake and management choices. In the current study we characterized the usability of three alternative methods of different rigor for quantifying stand-level evapotranspiration (ET), partitioned ET into tree transpiration (T), understory transpiration, interception, and soil evaporation (E S ) and determined their sensitivity to drought, and evaluated the reliability of soil moisture measurements by taking into account deep soil moisture dynamic. The analyses were conducted in an early-and in a mid-rotation stand of loblolly pine, the predominant species of southern US forest plantations. The three alternative methods for estimating ET were the eddy covariance measurements of water vapor fluxes (ET EC ), the water table fluctuation (ET WT ), and the soil moisture fluctuation (ET SM ). On annual and monthly scales, the three methods agreed to within 10 -20%, whereas on a daily scale, the values of ET SM and ET EC differed by up to 50% and ET SM and ET WT differed by up to 100%. The differences between the methods were attributed to root water extraction below measurement depth and to the sampling at different spatial scales. Regardless of the method used, ET at the early-rotation site was 15-30% lower than that at the mid-rotation site. The dry years did not affect ET at the mid-rotation site but reduced significantly ET at the early-rotation site. Soil moisture trends revealed the importance of measuring water content at several depths throughout the rooting zone because less than 20% of the water is stored in the top 30 cm of soil. Annually, E S represented approximately 9 and 14% of ET EC at the mid-rotation site and the early-rotation site, respectively. At the mid-rotation site, T accounted for approximately 70% of ET EC . Canopy interception was estimated to be 5-10% of annual precipitation and 6 -13% of total ET EC . At the early-rotation site, T accounted for only 35% of ET EC . At this site, transpiration from subdominant trees and shrubs represented 40 -45% of ET EC , indicating that understory was a significant part of the water budget. We concluded that the eddy covariance method is best for estimating ET at the fine temporal scale (i.e., daily), but other soil moisture and water table-based methods were equally reliable and cost-effective for quantifying seasonal ET dynamics. FOR. SCI. 58(5):497-512.Keywords: eddy covariance, loblolly pine, Pinus taeda, sapflow, soil moisture probes, water table L OBLOLLY PINE (PINUS TAEDA L.) REPRESENTS ONE-HALF OF THE STANDING PINE VOLUME in the southern United States (11.7 million ha) and is by far the single most commercially important forest tree species for the region, with more than 1 billion seedlings planted annually (McKeand et al. 2003). More than 1 million ha of intensively managed loblolly pine plantations are found along the lower coastal plain in eastern North Carolina. Large areas of the North Carolina...

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Soil water content measurements deliver reliable estimates of water fluxes: A comparative study in a beech and a spruce stand in the Tharandt forest (Saxony, Germany)

Cited by 68 publications

References 55 publications

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Soil water stable isotopes reveal evaporation dynamics at the soil–plant–atmosphere interface of the critical zone

Responses of shelterbelt stand transpiration to drought and groundwater variations in an arid inland river basin of Northwest China

A Comparison of Three Methods to Estimate Evapotranspiration in Two Contrasting Loblolly Pine Plantations: Age-Related Changes in Water Use and Drought Sensitivity of Evapotranspiration Components

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