Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?

Causes of over-dispersed barren "fairy circles" that are often surrounded by ca. 0.5 m tall peripheral grasses in a matrix of shorter (ca. 0.2 m tall) grasses in Namibian grasslands remain mysterious. It was hypothesized that the fairy circles are the consequence of self-organizing spatial...

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Autores principales:	Michael D Cramer, Nichole N Barger
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/32962f8b0eb249a1baa8c90e28339d4e
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spelling	oai:doaj.org-article:32962f8b0eb249a1baa8c90e28339d4e2021-11-18T08:59:27ZAre Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?1932-620310.1371/journal.pone.0070876https://doaj.org/article/32962f8b0eb249a1baa8c90e28339d4e2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23976962/?tool=EBIhttps://doaj.org/toc/1932-6203Causes of over-dispersed barren "fairy circles" that are often surrounded by ca. 0.5 m tall peripheral grasses in a matrix of shorter (ca. 0.2 m tall) grasses in Namibian grasslands remain mysterious. It was hypothesized that the fairy circles are the consequence of self-organizing spatial vegetation patterning arising from resource competition and facilitation. We examined the edaphic properties of fairy circles and variation in fairy circle size, density and landscape occupancy (% land surface) with edaphic properties and water availability at a local scale (<50 km) and with climate and vegetation characteristics at a regional scale. Soil moisture in the barren fairy circles declines from the center towards the periphery and is inversely correlated with soil organic carbon, possibly indicating that the peripheral grass roots access soil moisture that persists into the dry season within fairy circles. Fairy circle landscape occupancy is negatively correlated with precipitation and soil [N], consistent with fairy circles being the product of resource-competition. Regional fairy circle presence/absence is highly predictable using an empirical model that includes narrow ranges of vegetation biomass, precipitation and temperature seasonality as predictor variables, indicating that fairy circles are likely a climate-dependent emergent phenomenon. This dependence of fairy circle occurrence on climate explains why fairy circles in some locations may appear and disappear over time. Fairy circles are only over-dispersed at high landscape occupancies, indicating that inter-circle competition may determine their spacing. We conclude 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.Michael D CramerNichole N BargerPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 8, p e70876 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Michael D Cramer Nichole N Barger Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
description	Causes of over-dispersed barren "fairy circles" that are often surrounded by ca. 0.5 m tall peripheral grasses in a matrix of shorter (ca. 0.2 m tall) grasses in Namibian grasslands remain mysterious. It was hypothesized that the fairy circles are the consequence of self-organizing spatial vegetation patterning arising from resource competition and facilitation. We examined the edaphic properties of fairy circles and variation in fairy circle size, density and landscape occupancy (% land surface) with edaphic properties and water availability at a local scale (<50 km) and with climate and vegetation characteristics at a regional scale. Soil moisture in the barren fairy circles declines from the center towards the periphery and is inversely correlated with soil organic carbon, possibly indicating that the peripheral grass roots access soil moisture that persists into the dry season within fairy circles. Fairy circle landscape occupancy is negatively correlated with precipitation and soil [N], consistent with fairy circles being the product of resource-competition. Regional fairy circle presence/absence is highly predictable using an empirical model that includes narrow ranges of vegetation biomass, precipitation and temperature seasonality as predictor variables, indicating that fairy circles are likely a climate-dependent emergent phenomenon. This dependence of fairy circle occurrence on climate explains why fairy circles in some locations may appear and disappear over time. Fairy circles are only over-dispersed at high landscape occupancies, indicating that inter-circle competition may determine their spacing. We conclude 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.
format	article
author	Michael D Cramer Nichole N Barger
author_facet	Michael D Cramer Nichole N Barger
author_sort	Michael D Cramer
title	Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
title_short	Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
title_full	Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
title_fullStr	Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
title_full_unstemmed	Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
title_sort	are namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/32962f8b0eb249a1baa8c90e28339d4e
work_keys_str_mv	AT michaeldcramer arenamibianfairycirclestheconsequenceofselforganizingspatialvegetationpatterning AT nicholenbarger arenamibianfairycirclestheconsequenceofselforganizingspatialvegetationpatterning
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Are Namibian "fairy circles" the consequence of self-organizing spatial vegetation patterning?

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