Stochastic soil water balance under seasonal climates

Feng, Xue; Porporato, Amilcare; Rodrı́guez-Iturbe, Ignacio

doi:10.1098/rspa.2014.0623

Cited by 51 publications

(61 citation statements)

References 33 publications

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“…Here, we will use the crossing of mean soil moisture

⟨ s ⟩

as proxy for the mean crossing of stochastic soil moisture trajectories, even while acknowledging that they are not exactly the same (Rodriguez‐Iturbe & Porporato, , Chapter 3). By averaging the soil water balance (Eqn S1), we have an approximation describing the time course of mean soil moisture

⟨ s ⟩

over the dry season (Laio et al ., ; Feng et al ., ), where the effect of the minimal runoff losses is assumed to be negligible for determining the mean soil moisture trajectory,

\frac{d ⟨ s ⟩}{d t} = \{\begin{matrix} \frac{λ_{d}}{italicγ} - η \frac{false⟨ s false⟩ - s_{normalw}}{s^{*} - s_{normalw}} & s_{normalw} < false⟨ s false⟩ \leq s^{*} \\ \frac{λ_{d}}{italicγ} - η & s^{*} < false⟨ s false⟩ \leq s_{1} \end{matrix},

where

η = E_{normalmax} / false(n Z_{r} false)

γ = n Z_{normalr} / {italicα}_{normald}

, and λ d and α d are the mean rainfall frequency and intensity during the dry season. The mean soil moisture during the wet season

⟨ s_{normalwet} ⟩

(Eqn ) serves as the initial value for Eqn (Fig.…”

Section: Methodsmentioning

confidence: 99%

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Reconciling seasonal hydraulic risk and plant water use through probabilistic soil–plant dynamics

Feng

Dawson

Ackerly

et al. 2017

Global Change Biology

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Current models used for predicting vegetation responses to climate change are often guided by the dichotomous needs to resolve either (i) internal plant water status as a proxy for physiological vulnerability or (ii) external water and carbon fluxes and atmospheric feedbacks. Yet, accurate representation of fluxes does not always equate to accurate predictions of vulnerability. We resolve this discrepancy using a hydrodynamic framework that simultaneously tracks plant water status and water uptake. We couple a minimalist plant hydraulics model with a soil moisture model and, for the first time, translate rainfall variability at multiple timescales - with explicit descriptions at daily, seasonal, and interannual timescales - into a physiologically meaningful metric for the risk of hydraulic failure. The model, parameterized with measured traits from chaparral species native to Southern California, shows that apparently similar transpiration patterns throughout the dry season can emerge from disparate plant water potential trajectories, and vice versa. The parsimonious set of parameters that captures the role of many traits across the soil-plant-atmosphere continuum is then used to establish differences in species sensitivities to shifts in seasonal rainfall statistics, showing that co-occurring species may diverge in their risk of hydraulic failure despite minimal changes to their seasonal water use. The results suggest potential shifts in species composition in this region due to species-specific changes in hydraulic risk. Our process-based approach offers a quantitative framework for understanding species sensitivity across multiple timescales of rainfall variability and provides a promising avenue toward incorporating interactions of temporal variability and physiological mechanisms into drought response models.

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“…Here, we will use the crossing of mean soil moisture

⟨ s ⟩

⟨ s ⟩

over the dry season (Laio et al ., ; Feng et al ., ), where the effect of the minimal runoff losses is assumed to be negligible for determining the mean soil moisture trajectory,

\frac{d ⟨ s ⟩}{d t} = \{\begin{matrix} \frac{λ_{d}}{italicγ} - η \frac{false⟨ s false⟩ - s_{normalw}}{s^{*} - s_{normalw}} & s_{normalw} < false⟨ s false⟩ \leq s^{*} \\ \frac{λ_{d}}{italicγ} - η & s^{*} < false⟨ s false⟩ \leq s_{1} \end{matrix},

where

η = E_{normalmax} / false(n Z_{r} false)

γ = n Z_{normalr} / {italicα}_{normald}

, and λ d and α d are the mean rainfall frequency and intensity during the dry season. The mean soil moisture during the wet season

⟨ s_{normalwet} ⟩

(Eqn ) serves as the initial value for Eqn (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…In cases where the rainfall during the dry season is high enough to generate substantial runoff and invalidate the macroscopic approximation, an alternate, iterative approach to finding the trajectory of mean soil moisture should be used [e.g., the self‐consistent approximation in Feng et al . ()].…”

Section: Methodsmentioning

confidence: 99%

Reconciling seasonal hydraulic risk and plant water use through probabilistic soil–plant dynamics

Feng

Dawson

Ackerly

et al. 2017

Global Change Biology

Self Cite

View full text Add to dashboard Cite

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“…[] and Feng et al . [] for the case of seasonal changes in the ensemble soil moisture. The potential advantages provided by overcoming the closure problem would be remarkable in that the resulting equations are deterministic dynamical systems that naturally embed the effect of stochastic external forcing while being amenable to dynamical system analysis.…”

Section: The Challenge Of Stochastic Forcing and Nonlinear Interactionsmentioning

confidence: 99%

Ecohydrological modeling in agroecosystems: Examples and challenges

Porporato

Feng

Manzoni

et al. 2015

Water Resources Research

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Human societies are increasingly altering the water and biogeochemical cycles to both improve ecosystem productivity and reduce risks associated with the unpredictable variability of climatic drivers. These alterations, however, often cause large negative environmental consequences, raising the question as to how societies can ensure a sustainable use of natural resources for the future. Here we discuss how ecohydrological modeling may address these broad questions with special attention to agroecosystems. The challenges related to modeling the two-way interaction between society and environment are illustrated by means of a dynamical model in which soil and water quality supports the growth of human society but is also degraded by excessive pressure, leading to critical transitions and sustained societal growth-collapse cycles. We then focus on the coupled dynamics of soil water and solutes (nutrients or contaminants), emphasizing the modeling challenges, presented by the strong nonlinearities in the soil and plant system and the unpredictable hydroclimatic forcing, that need to be overcome to quantitatively analyze problems of soil water sustainability in both natural and agricultural ecosystems. We discuss applications of this framework to problems of irrigation, soil salinization, and fertilization and emphasize how optimal solutions for large-scale, long-term planning of soil and water resources in agroecosystems under uncertainty could be provided by methods from stochastic control, informed by physically and mathematically sound descriptions of ecohydrological and biogeochemical interactions.

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“…In the absence of precipitation, soil moisture remains below field capacity, so gravitational runoff and drainage in the rooting zone are negligible (Feng et al. , Dingman ). This model tracks total moisture and thus allows for redistribution within the rooting zone, for example through hydraulic lift or catenary subsurface flow, although we do not model these processes explicitly.…”

Section: Methodsmentioning

confidence: 99%

Tree water balance drives temperate forest responses to drought

Berdanier

Clark

2018

Ecology

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Intensifying drought is increasingly linked to global forest diebacks. Improved understanding of drought impacts on individual trees has provided limited insight into drought vulnerability in part because tree moisture access and depletion is difficult to quantify. In forests, moisture reservoir depletion occurs through water use by the trees themselves. Here, we show that drought impacts on tree fitness and demographic performance can be predicted by tracking the moisture reservoir available to trees as a mass balance, estimated in a hierarchical state-space framework. We apply this model to multiple seasonal droughts with tree transpiration measurements to demonstrate how species and size differences modulate moisture availability across landscapes. The depletion of individual moisture reservoirs can be tracked over the course of droughts and linked to biomass growth and reproductive output. This mass balance approach can predict individual moisture deficit, tree demographic performance, and drought vulnerability throughout forest stands based on measurements from a sample of trees.

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Stochastic soil water balance under seasonal climates

Cited by 51 publications

References 33 publications

Reconciling seasonal hydraulic risk and plant water use through probabilistic soil–plant dynamics

Reconciling seasonal hydraulic risk and plant water use through probabilistic soil–plant dynamics

Ecohydrological modeling in agroecosystems: Examples and challenges

Tree water balance drives temperate forest responses to drought

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