An analysis of soil moisture dynamics using multi-year data from a network of micrometeorological observation sites

Miller, G. R.; Baldocchi, Dennis; Law, B. E.; Meyers, Tilden P.

doi:10.1016/j.advwatres.2006.10.002

Cited by 71 publications

(68 citation statements)

References 41 publications

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“…At this site, the discrepancy between measured throughout the whole soil profile and the upper soil profile there was due to the lower soil layers (60 -140 cm) contributing a larger amount of water to daily water depletion relative to the upper layers (10 -60 cm) when was low (Meiresonne et al 2003, Warren et al 2005. These results suggest that great care should be taken when one is comparing T and ET EC to soil water dynamics measured from the upper soil profile even after correcting for root profile distribution (Miller et al 2007). However, some of the differences in soil water storage measured throughout the whole soil profile and the upper soil profile are expected to be dampened by water hydraulically redistributed by deep roots (Warren et al 2007).…”

Section: Contributions Of Soil Water Storage To Et: Whole Profile Vermentioning

confidence: 91%

“…Therefore, accurately defining the relationships between soil water content and water fluxes from the soil and the vegetation is fundamental to improving hydrologic modeling. However, to date the majority of field investigations have relied on monitoring the first 10 -40 cm soil profile to characterize whole stand soil water depletion and water use, whereas the rooting zone is usually much deeper (Warren et al 2005, Miller et al 2007.…”

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confidence: 99%

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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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Section: Contributions Of Soil Water Storage To Et: Whole Profile Vermentioning

confidence: 91%

mentioning

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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“…average climate and soil texture, and biotic characteristics including soil saturation thresholds at which vegetation can influence soil water losses. However, the shapes of analytical soil moisture pdfs are generally not consistent with observations when literature values for model parameters are used (Miller et al, 2007). Analytical pdfs have never been directly compared to empirical pdfs derived from measurements beyond the point scale.…”

Section: Introductionmentioning

confidence: 89%

“…Few studies have directly confronted the governing equations of the stochastic soil 20 water balance model with observed soil moisture data and fewer have attempted to optimize model parameters to best fit soil moisture observations. Miller et al, (2007) calibrated soil moisture pdfs to project vegetation stress in a changing climate. Chen et al, (2008) related evapotranspiration observations at the stand scale to soil moisture values using a Bayesian inversion approach, and Volo et al, (2014) calibrated the soil moisture loss curve to investigate effects of irrigation scheduling and precipitation on soil moisture dynamics and plant stress.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic inference of ecohydrological parameters using observations from point to satellite scales

Bassiouni¹,

Higgins²,

Still³

et al. 2017

Preprint

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Abstract. Ecohydrological parameters that describe vegetation controls on soil moisture dynamics are not easy to measure at hydrologically meaningful scales and site-specific values are rarely available. We hypothesize that sufficient information required to determine these ecohydrological parameters is encoded in empirical probability density functions (pdfs) of soil 10 saturation, and that this information can be extracted through inverse modeling of the commonly used stochastic soil water balance. We developed a generalizable Bayesian inference approach to estimate soil saturation thresholds at which plants control soil water losses, based only on soil texture, rainfall and soil moisture data at point, footprint, and satellite scales. The optimal analytical soil saturation pdfs were statistically consistent with empirical pdfs and parameter uncertainties were on average under 10 %. Parameter estimates were most constrained for scales and locations at which soil water dynamics are 15 more sensitive to the fitted ecohydrological parameters of interest. The algorithm convergence was most successful and the best goodness-of-fit statistics were obtained at the satellite scale. Robust and accurate results were obtained with as little as 75 daily observations randomly sampled from the full records, demonstrating the advantage of analyzing soil saturation pdfs instead of time series. A sensitivity analysis showed that estimates of soil saturation thresholds at which plants control soil water losses were not sensitive to soil depth and near-surface observations are valuable to characterize ecohydrological 20 factors driving soil water dynamics at ecosystem scales. This work combined modeling and empirical approaches in ecohydrology and provided a simple framework to obtain analytical descriptions of soil moisture dynamics at a range of spatial scales that are consistent with soil moisture observations.

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“…It is however necessary to exclude these sites, as the absolute values and dynamics of soil moisture in the uppermost layers can differ greatly from the conditions at greater depths (Miller et al, 2007). For each site, the suitability of SWC measurements was determined through a subjective assessment of the SWC 15 curves.…”

Section: Estimated Through Model Calibrationmentioning

confidence: 99%

Testing an optimality-based model of rooting zone water storage capacity in temperate forests

Speich¹,

Lischke²,

Zappa³

2017

Preprint

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Abstract. Rooting zone water storage capacity ! is a crucial parameter in models of hydrology, ecosystem gas exchange 10 and vegetation dynamics. Despite its importance, this parameter is still poorly constrained and subject to high uncertainty.We tested the analytical, optimality-based model of effective rooting depth proposed by Guswa (2010) with regard to its applicability for parameterizing ! in temperate forests. The model assumes that plants dimension their rooting systems in order to maximize net carbon gain. Results from this model were compared against values obtained by calibrating a local water balance model against latent heat flux and soil moisture observations from 15 eddy covariance sites. To increase the 15 applicability of the rooting depth model, we provide a numerical approximation of its underlying probabilistic soil moisture model.The calibration and validation of the local water balance model showed that the concept of a single rooting zone storage capacity was appropriate at most temperate and cold sites, but not at Mediterranean sites and for very coarse soils. At a majority of sites, the estimates of ! are generally in good agreement. However, mismatches were found in stands dominated 20 by Norway spruce, especially at high elevations. These mismatches were attributed to the fact that the model does not consider rooting depth limitations due to oxygen stress and low soil temperature. Also, it is not clear whether the rooting behavior of pines on coarse soils is captured properly. Nevertheless, the overall good agreement suggests that this model may be useful for generating estimates of rooting zone storage capacity for both hydrological and ecological applications.Another potential use is the dynamic parameterization of the rooting zone in process-based models, which greatly increases 25 the reliability of transient climate-impact assessment studies.

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An analysis of soil moisture dynamics using multi-year data from a network of micrometeorological observation sites

Cited by 71 publications

References 41 publications

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

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

Probabilistic inference of ecohydrological parameters using observations from point to satellite scales

Testing an optimality-based model of rooting zone water storage capacity in temperate forests

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