Discovery of fairy circles in Australia supports self-organization theory

@article{Getzin2016DiscoveryOF,
  title={Discovery of fairy circles in Australia supports self-organization theory},
  author={Stephan Getzin and Hezi Yizhaq and Bronwyn Bell and Todd E. Erickson and Anthony C. Postle and Itzhak Katra and Omer Tzuk and Yuval R. Zelnik and Kerstin Wiegand and Thorsten Wiegand and Ehud Meron},
  journal={Proceedings of the National Academy of Sciences},
  year={2016},
  volume={113},
  pages={3551 - 3556}
}
Significance Pattern-formation theory predicts that vegetation gap patterns, such as the fairy circles of Namibia, emerge through the action of pattern-forming biomass–water feedbacks and that such patterns should be found elsewhere in water-limited systems around the world. We report here the exciting discovery of fairy-circle patterns in the remote outback of Australia. Using fieldwork, remote sensing, spatial pattern analysis, mathematical modeling, and pattern-formation theory we show that… 

Figures from this paper

Spatial Self-Organization of Ecosystems: Integrating Multiple Mechanisms of Regular-Pattern Formation.
TLDR
Evidence is found that spotted and gapped vegetation patterns generated by ants, termites, and other subterranean animals are globally widespread, locally important for ecosystem functioning, and consistent with models of intraspecific territoriality.
A theoretical foundation for multi-scale regular vegetation patterns
TLDR
A general theoretical foundation for self-organization of social-insect colonies is provided, validated using data from four continents, which demonstrates that intraspecific competition between territorial animals can generate the large-scale hexagonal regularity of these patterns.
Fairy circles reveal the resilience of self-organized salt marshes
TLDR
It is shown that transient fairy circle patterns in intertidal salt marshes can both infer the underlying ecological mechanisms and provide a measure of resilience and imply that the emergence of transient patterns can identify the ecological processes underlying pattern formation and the factors determining the ecological resilience of salt marsh ecosystems.
Edaphic properties enable facilitative and competitive interactions resulting in fairy circle formation
TLDR
The evidence is consistent with an emergent vegetation pattern explanation for the origins of fairy circles and that the circles are more closely associated with a highly connective edaphic environment, rather than with particular biota.
Fairy circle landscapes under the sea
TLDR
A model explaining the formation of fairy circles and patterns in seagrasses along the Mediterranean coast reveals that the different seascapes observed hold diagnostic power as to the proximity of seagRass meadows to extinction points that can be used to identify ecosystems at risks.
Ecohydrological interactions within “fairy circles” in the Namib Desert: Revisiting the self‐organization hypothesis
Vegetation patterns such as rings, bands, and spots are recurrent characteristics of resource‐limited arid and semiarid ecosystems. One of the most recognizable vegetation patterns is the millions of
Fairy circles or ghosts of termitaria? Pavement termites as alternative causes of circular patterns in vegetation of desert Australia
TLDR
Although it is accepted that water redistribution occurs between bare and vegetated areas in Australian desert grasslands, there is evidence that bare patches are subterranean termitaria, both active and inactive (abandoned).
Bridging ecology and physics: Australian fairy circles regenerate following model assumptions on ecohydrological feedbacks
So‐called fairy circles (FCs) comprise a spatially periodic gap pattern in arid grasslands of Namibia and north‐west Western Australia. This pattern has been explained with scale‐dependent
Contrasting Global Patterns of Spatially Periodic Fairy Circles and Regular Insect Nests in Drylands
Numerical analysis of spatial pattern is widely used in ecology to describe the characteristics of floral and faunal distributions. These methods allow attribution of pattern to causal mechanisms by
The shaping role of self-organization: linking vegetation patterning, plant traits and ecosystem functioning
TLDR
It is demonstrated that scale-dependent feedback is driving irregular spatial pattern formation of vegetation in self-organized salt marsh ecosystems dominated by Scirpus mariqueter, and this work helps to link between the so-far largely unconnected fields of self-organization theory and trait-based, functional ecology.
...
...

References

SHOWING 1-10 OF 48 REFERENCES
Pattern-formation approach to modelling spatially extended ecosystems
Are Namibian “Fairy Circles” the Consequence of Self-Organizing Spatial Vegetation Patterning?
TLDR
It is concluded that fairy circles are likely to be an emergent arid-grassland phenomenon that forms as a consequence of peripheral grass resource-competition and that the consequent barren circle may provide a resource-reservoir essential for the survival of the larger peripheral grasses and provides a habitat for fossicking fauna.
Adopting a spatially explicit perspective to study the mysterious fairy circles of Namibia
TLDR
Analysis of the spatial patterns of fairy circles obtained from representative 25-ha aerial images of north-west Namibia supports the hypothesis that fairy circles are self-organized vegetation patterns that emerge from positive biomass-water feedbacks involving water transport by extended root systems and soil-water diffusion.
Gradual regime shifts in fairy circles
TLDR
It is shown that transitions between alternative stable states in spatially extended ecosystems are not necessarily abrupt; cascades of local shifts between a multitude of stable states, composed of patterned and uniform domains, can result in global regime shifts that proceed gradually.
The Biological Underpinnings of Namib Desert Fairy Circles
TLDR
The sand termite Psammotermes allocerus generates local ecosystems, so-called fairy circles, through removal of short-lived vegetation that appears after rain, leaving circular barren patches, which results in the formation of rings of perennial vegetation that facilitate termite survival and locally increase biodiversity.
Spatial decoupling of facilitation and competition at the origin of gapped vegetation patterns.
TLDR
This study contributes to the growing awareness that combined facilitative and competitive plant interactions can induce landscape-scale patterns and shape the two-way feedback loops between environment and vegetation.
Microtopography alters self‐organized vegetation patterns in water‐limited ecosystems
[1] In terrestrial systems limited by water availability the spatial distribution of vegetation can self-organize into a mosaic of vegetated patches and bare soil. Spatially extensive competition for
Periodic versus scale-free patterns in dryland vegetation
TLDR
Using a spatially explicit mathematical model for vegetation dynamics in water-limited systems, a general mechanism for global competition is unraveled: fast spatial distribution of the water resource relative to processes that exploit or absorb it.
Regular pattern formation in real ecosystems.
Self‐Organization of Vegetation in Arid Ecosystems
TLDR
The results show that self-organized vegetation patterns observed in arid ecosystems might all be the result of spatial self-organization, caused by one single mechanism: water infiltrates faster into vegetated ground than into bare soil, leading to net displacement of surface water to vegetated patches.
...
...