Estimates of tree root water uptake from soil moisture profile dynamics

Jackisch, Conrad; Knoblauch, S.; Blume, Theresa; Zehe, Erwin; Hassler, Sibylle K.

doi:10.5194/bg-2019-466

Cited by 4 publications

(10 citation statements)

References 23 publications

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Section: Discussionmentioning

confidence: 99%

“…The rootwater algorithm (Jackisch and Mälicke, 2020) fits a model to the daily variations of SWC in a given soil layer to calculate root water uptake. In the original publication, the authors consider a model fit of NSE > 0.5 as indicative of most reliable RWU estimates (Jackisch et al, 2020). Our RWU calculations did not always meet this criterion, with some values of NSE < 0.5 notably in early summer (before DoY 120 in 2017, or DoY 170 in 2018) and late summer (after DoY 220 in 2018) (Fig.3), meaning that processes other than root water uptake (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Bréda et al, 1995 in an oak site, Bréda et al, 2002 in an ash forest). It is however not systematic and, for instance, a regular, not increasing, and minimal contribution of soil layers below 170 cm depth was reported in a Beech forest along a mild summer in Germany (Jackisch et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…In a methods comparison (Guderle and Hildebrandt, 2015), this approach using daily SWC oscillations proved to be the best regarding a combination of criteria: the quality of estimations and lesser induced error due to moisture sensor accuracy (the calibration error). Consequently, we focused on this method, and calculated RWU at our site from SWC measurements with the python package rootwater (Jackisch and Mälicke, 2020). This algorithm analyses daily fluctuations in SWC and takes into account possible hydraulic redistribution, a mechanism by which water is moved via the root system from moister to drier soil layers (Caldwell et al, 1998; Ishikawa and Bledsoe, 2000; Neumann and Cardon, 2012).…”

Section: Methodsmentioning

confidence: 99%

“…For selected days, a reference daily moisture profile was built, based on the SWC values at sunset/sunrise, and linear interpolations. The reference reflects “perfect” RWU over daytime and diffusion over night time (Jackisch et al, 2020). The theoretical step shape profile was then compared to the observed profile thanks to an evaluation of the Nash-Sutcliffe efficiency (NSE, Nash and Sutcliffe, 1970).…”

Section: Methodsmentioning

confidence: 99%

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Contribution of deep soil layers to the transpiration of a temperate deciduous forest: quantification and implications for the modelling of productivity

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et al. 2022

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Climate change is imposing drier atmospheric and edaphic conditions on temperate forests. Here, we investigated how subsoil (down to 300 cm) water extraction contributed to the provision of water in the Fontainebleau-Barbeau temperate oak forest over two years, including the 2018 record drought. Deep water provision was key to sustain canopy transpiration during drought, with layers below 150 cm contributing up to 60% of the transpired water in August 2018, despite their very low density of fine roots. We further showed that soil databases used to parameterize ecosystem models clearly underestimated the amount of water extractable from the soil by trees. The consensus database established for France gave an estimate of 207 mm for the soil water holding capacity (SWHC) at our study site, when our estimate based on the analysis of soil water content measurements was 1.9 times higher, reaching 390+/-17 mm. Running the CASTANEA forest model with the database-derived SWHC yielded a 350 gC m-2 y-1 average underestimation of annual gross primary productivity under Global Change Biology For Review Only current climate, reaching up to 700 gC m-2 y-1 under climate change scenario RCP8.5. Correctly estimating SWHC is a challenge for accurate simulations of the carbon cycle in a changing climate and we showed that subsoil SWC measurements are needed for this.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Contribution of deep soil layers to the transpiration of a temperate deciduous forest: quantification and implications for the modelling of productivity

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First Evidence of Correlation Between Evapotranspiration and Gravity at a Daily Time Scale From Two Vertically Spaced Superconducting Gravimeters

Carrière

Loiseau

Champollion

et al. 2021

Geophysical Research Letters

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Evapotranspiration (ET) is a key variable to understanding eco-hydrosystems because it links water, carbon, and energy cycles (Fisher, 2014). ET is a major component of the water cycle, accounting for approximately 70% of precipitated water at the continental scale (Fisher et al., 2017;Oki & Kanae, 2006). Several approaches exist for estimating ET, but large uncertainties persist and estimates remain difficult to validate, particularly at large scale (Müller & Bolte, 2009;Verstraeten et al., 2008). New approaches for estimating ET are crucially needed to improve our understanding of related processes.Gravimetry is a geophysical method that measures the gravitational acceleration field (g). During the last decades, progress has led to the development of devices that can now achieve precision of a few nm/s 2 and obtain highly accurate temporal monitoring (Van Camp et al., 2006). These advances now allow to study the dynamics of ET. Data from the GRACE (Gravity Recovery and Climate Experiment) satellite have been used to study ET (Long

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Embracing fine-root system complexity to improve the predictive understanding of ecosystem functioning

Wang

McCormack

Ricciuto

et al. 2022

Preprint

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Projecting the functioning of the biosphere requires a holistic consideration of whole-ecosystem processes. Although improving leaf and canopy processes has been the focus of ecosystem model development since the 1970s, the arbitrary homogenization of fine-root systems into a single pool is at odds with observations. This discrepancy has increased in the last two decades as accelerated conceptual and empirical advances have revealed functional differentiation and cooperation conferred by the hierarchical structure of fine-root orders and associations with mycorrhizal fungi in fine-root systems. To close this model-data gap, we propose a 3-pool structure comprising Transport and Absorptive fine roots with Mycorrhizal fungi (TAM) to model vertically resolved fine-root systems across organizational and spatial-temporal scales. A comparison of TAM to the single fine-root structure in a state-of-the-art Earth System Model using the big-leaf approach demonstrates robust impacts on carbon cycling in temperate forests, lending further quantitative support to the empirical and theoretical basis for TAM. Strong support in both theory and practice therefore suggests a move beyond the useful but incorrect paradigm of single-pool homogenization, echoing a broad trend of embracing ecological complexities in terrestrial ecosystem modelling. Although challenges lay ahead towards realizing TAM in ecologically realistic demography models simulating emergent functioning from pattern and diversity, adoption of TAM by both modelers and empiricists holds promise to build a better predictive understanding of ecosystem functioning in the context of global change.

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Estimates of tree root water uptake from soil moisture profile dynamics

Cited by 4 publications

References 23 publications

Contribution of deep soil layers to the transpiration of a temperate deciduous forest: quantification and implications for the modelling of productivity

Contribution of deep soil layers to the transpiration of a temperate deciduous forest: quantification and implications for the modelling of productivity

First Evidence of Correlation Between Evapotranspiration and Gravity at a Daily Time Scale From Two Vertically Spaced Superconducting Gravimeters

Embracing fine-root system complexity to improve the predictive understanding of ecosystem functioning

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