A fast–slow model of banded vegetation pattern formation in drylands

Gandhi, Punit; Bonetti, Sara; Iams, Sarah; Porporato, Amilcare; Silber, Mary

doi:10.1016/j.physd.2020.132534

Cited by 15 publications

(25 citation statements)

References 48 publications

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“…This is common practice in the study of stripe patterns (e.g. (Gandhi et al 2020;Klausmeier 1999; Sherratt 2016)) as outcomes are similar to those obtained on a two-dimensional spatial domain. However, it is important to emphasise that this may lead to an overestimation of a pattern's resilience to increases in environmental stress, as it cannot capture the break-up of banded patterns into spot patterns (Sewalt and Doelman 2017;Siero et al 2015).…”

Section: Model Detailssupporting

confidence: 61%

Species coexistence in resource-limited patterned ecosystems is facilitated by the interplay of spatial self-organisation and intraspecific competition

Eigentler

2020

Preprint

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The exploration of mechanisms that enable species coexistence under competition for a sole limiting resource is widespread across ecology. One classical example is the coexistence of herbaceous and woody species in self-organised dryland vegetation patterns. Previous theoretical investigations have explained this phenomenon by making strong assumptions on the differences between grasses and trees (e.g. contrasting dispersal behaviours or different functional responses to soil moisture). Motivated by classical theory on Lotka-Volterra competition models, I argue that the interplay between interspecific and intraspecific competition can explain species coexistence without relying on such assumptions. I use an ecohydrological reaction-advection-diffusion system that captures the interactions of two plant species with an explicitly modelled resource to show that coexistence is facilitated by strong intraspecific competition of the species superior in its colonisation abilities, if its competitor's local average fitness is higher. The inclusion of a spatial self-organisation principle yields significant differences from the nonspatial case in which strong intraspecific competition of the locally superior species enables coexistence. Results presented in this paper also capture the empirically observed spatial species distribution in single bands of vegetation and propose differences in plants' dispersal behaviour as its cause.

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Section: Model Detailssupporting

confidence: 61%

Species coexistence in resource-limited patterned ecosystems is facilitated by the interplay of spatial self-organisation and intraspecific competition

Eigentler

2020

Preprint

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“…The present study is limited in scope to rainfall with fixed intervals between identical showers of constant intensity. However, the proposed framework is well suited to investigate the effects on vegetation patterns of rainfall seasonality, stochasticity, intermittency and intensity, topics which have been previously examined with phenomenological treatments of storm‐scale processes (Baudena, von Hardenberg, & Provenzale, 2013; D'Odorico et al, 2006; Gandhi et al, 2019; Kletter et al, 2009; Ursino & Contarini, 2006). Indeed, the model modifications that would be necessary to explore rainfall seasonality, intermittency and stochasticity are trivial, namely, adjusting the wait intervals between storm events.…”

Section: Discussionmentioning

confidence: 99%

“…The modification slows the rates of biomass growth and decay while soil moisture is limited, reflecting drought‐adaptations in desert vegetation. The model forms a broad suite of vegetation patterns and is the basis for an extensive modelling literature exploring the dynamics of these patterns (Baartman, Temme, & Saco, 2018; Dagbovie & Sherratt, 2014; Gandhi et al, 2019; Pueyo, Kéfi, Alados, & Rietkerk, 2008; Saco, Willgoose, & Hancock, 2007).…”

Section: Methodsmentioning

confidence: 99%

“…Loss of vegetation cover in drylands is known to risk irreversible desertification (Kéfi et al, 2007; Rietkerk, Dekker, De Ruiter, & van de Koppel, 2004). For the globally distributed suite of dryland ecosystems where vegetation forms regular spatial patterns (Bromley, Brouwer, Barker, Gaze, & Valentine, 1997; Deblauwe, Barbier, Couteron, Lejeune, & Bogaert, 2008; Penny, Daniels, & Thompson, 2013), such ecological collapse may be preceded by changes in the spatial pattern of vegetation (Gandhi, Bonetti, Iams, Porporato, & Silber, 2019; Guttal & Jayaprakash, 2007; HilleRisLambers, Rietkerk, van den Bosch, Prins, & de Kroon, 2001; Rietkerk et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…By contrast, high‐intensity storms generate runoff across the whole hillslope, resulting in more uniform infiltration fields within vegetated areas, as shown in Figure S1. Recently, Gandhi et al (2019) used a timescale separation approach to simulate rainfall and storm responses on their appropriate timescales; however, this study retained a phenomenological representation of overland flow and infiltration.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sensitivity of dryland vegetation patterns to storm characteristics

Crompton

Thompson

2021

Ecohydrology

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Ecohydrological phenomena are o ften multiscale in nature, with behavioTur that emerges from the interaction of tightly coupled systems having characteristic timescales that differ by orders of magnitude. Models address these differences using timescale separation methods, where each system is held in psuedo‐steady state while the other evolves. When the computational demands of solving the ‘fast’ system are large, this strategy can become numerically intractable. Here, we use emulation modelling to accelerate the simulation of a computationally intensive ‘fast’ system: overland flow. We focus on dryland ecosystems in which storms generate overland flow, on timescales of 101 − 2 s. In these ecosystems, overland flow delivers crucial water inputs to vegetation, which grows and disperses ‘slowly’, on timescales of 107 − 9 s. Emulation allows for a physically realistic treatment of flow, advancing on phenomenological descriptions used in previous studies. Resolving the within‐storm processes reveals novel dynamics, including new transition pathways from patchy vegetation to desertification, that are specifically controlled by storm processes.

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