A theoretical foundation for multi-scale regular vegetation patterns

Corina E. Tarnita, Juan A. Bonachela, Efrat Sheffer, Jennifer A. Guyton, Tyler C. Coverdale, Ryan A. Long, Robert M. Pringle

Research output: Contribution to journalLetter

36 Citations (Scopus)

Abstract

Self-organized regular vegetation patterns are widespread and thought to mediate ecosystem functions such as productivity and robustness, but the mechanisms underlying their origin and maintenance remain disputed. Particularly controversial are landscapes of overdispersed (evenly spaced) elements, such as North American Mima mounds, Brazilian murundus, South African heuweltjies, and, famously, Namibian fairy circles. Two competing hypotheses are currently debated. On the one hand, models of scale-dependent feedbacks, whereby plants facilitate neighbours while competing with distant individuals, can reproduce various regular patterns identified in satellite imagery. Owing to deep theoretical roots and apparent generality, scale-dependent feedbacks are widely viewed as a unifying and near-universal principle of regular-pattern formation despite scant empirical evidence. On the other hand, many overdispersed vegetation patterns worldwide have been attributed to subterranean ecosystem engineers such as termites, ants, and rodents. Although potentially consistent with territorial competition, this interpretation has been challenged theoretically and empirically and (unlike scale-dependent feedbacks) lacks a unifying dynamical theory, fuelling scepticism about its plausibility and generality. Here we provide a general theoretical foundation for self-organization of social-insect colonies, validated using data from four continents, which demonstrates that intraspecific competition between territorial animals can generate the large-scale hexagonal regularity of these patterns. However, this mechanism is not mutually exclusive with scale-dependent feedbacks. Using Namib Desert fairy circles as a case study, we present field data showing that these landscapes exhibit multi-scale patterning-previously undocumented in this system-that cannot be explained by either mechanism in isolation. These multi-scale patterns and other emergent properties, such as enhanced resistance to and recovery from drought, instead arise from dynamic interactions in our theoretical framework, which couples both mechanisms. The potentially global extent of animal-induced regularity in vegetation-which can modulate other patterning processes in functionally important ways-emphasizes the need to integrate multiple mechanisms of ecological self-organization.

LanguageEnglish
Pages398-401
Number of pages4
JournalNature
Volume541
Issue number7637
Early online date18 Jan 2017
DOIs
Publication statusPublished - 19 Jan 2017

Fingerprint

self organization
vegetation
social insect
animal
intraspecific competition
termite
ecosystem function
satellite imagery
rodent
ant
desert
drought
productivity
ecosystem
continent

Keywords

  • climate-change ecology
  • theoretical ecology
  • community ecology
  • ecosystem ecology
  • ecological modelling

Cite this

Tarnita, C. E., Bonachela, J. A., Sheffer, E., Guyton, J. A., Coverdale, T. C., Long, R. A., & Pringle, R. M. (2017). A theoretical foundation for multi-scale regular vegetation patterns. Nature, 541(7637), 398-401. https://doi.org/10.1038/nature20801
Tarnita, Corina E. ; Bonachela, Juan A. ; Sheffer, Efrat ; Guyton, Jennifer A. ; Coverdale, Tyler C. ; Long, Ryan A. ; Pringle, Robert M. / A theoretical foundation for multi-scale regular vegetation patterns. In: Nature. 2017 ; Vol. 541, No. 7637. pp. 398-401.
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Tarnita, CE, Bonachela, JA, Sheffer, E, Guyton, JA, Coverdale, TC, Long, RA & Pringle, RM 2017, 'A theoretical foundation for multi-scale regular vegetation patterns' Nature, vol. 541, no. 7637, pp. 398-401. https://doi.org/10.1038/nature20801

A theoretical foundation for multi-scale regular vegetation patterns. / Tarnita, Corina E.; Bonachela, Juan A.; Sheffer, Efrat; Guyton, Jennifer A.; Coverdale, Tyler C.; Long, Ryan A.; Pringle, Robert M.

In: Nature, Vol. 541, No. 7637, 19.01.2017, p. 398-401.

Research output: Contribution to journalLetter

TY - JOUR

T1 - A theoretical foundation for multi-scale regular vegetation patterns

AU - Tarnita, Corina E.

AU - Bonachela, Juan A.

AU - Sheffer, Efrat

AU - Guyton, Jennifer A.

AU - Coverdale, Tyler C.

AU - Long, Ryan A.

AU - Pringle, Robert M.

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N2 - Self-organized regular vegetation patterns are widespread and thought to mediate ecosystem functions such as productivity and robustness, but the mechanisms underlying their origin and maintenance remain disputed. Particularly controversial are landscapes of overdispersed (evenly spaced) elements, such as North American Mima mounds, Brazilian murundus, South African heuweltjies, and, famously, Namibian fairy circles. Two competing hypotheses are currently debated. On the one hand, models of scale-dependent feedbacks, whereby plants facilitate neighbours while competing with distant individuals, can reproduce various regular patterns identified in satellite imagery. Owing to deep theoretical roots and apparent generality, scale-dependent feedbacks are widely viewed as a unifying and near-universal principle of regular-pattern formation despite scant empirical evidence. On the other hand, many overdispersed vegetation patterns worldwide have been attributed to subterranean ecosystem engineers such as termites, ants, and rodents. Although potentially consistent with territorial competition, this interpretation has been challenged theoretically and empirically and (unlike scale-dependent feedbacks) lacks a unifying dynamical theory, fuelling scepticism about its plausibility and generality. Here we provide a general theoretical foundation for self-organization of social-insect colonies, validated using data from four continents, which demonstrates that intraspecific competition between territorial animals can generate the large-scale hexagonal regularity of these patterns. However, this mechanism is not mutually exclusive with scale-dependent feedbacks. Using Namib Desert fairy circles as a case study, we present field data showing that these landscapes exhibit multi-scale patterning-previously undocumented in this system-that cannot be explained by either mechanism in isolation. These multi-scale patterns and other emergent properties, such as enhanced resistance to and recovery from drought, instead arise from dynamic interactions in our theoretical framework, which couples both mechanisms. The potentially global extent of animal-induced regularity in vegetation-which can modulate other patterning processes in functionally important ways-emphasizes the need to integrate multiple mechanisms of ecological self-organization.

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KW - theoretical ecology

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KW - ecological modelling

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Tarnita CE, Bonachela JA, Sheffer E, Guyton JA, Coverdale TC, Long RA et al. A theoretical foundation for multi-scale regular vegetation patterns. Nature. 2017 Jan 19;541(7637):398-401. https://doi.org/10.1038/nature20801