The life cycle and life span of Namibian fairy circles.

In Namibia of southwestern Africa, the sparse grasslands that develop on deep sandy soils under rainfall between 50 and 100 mm per annum are punctuated by thousands of quasi-circular bare spots, usually surrounded by a ring of taller grass. The causes of these so-called "fairy circles" are...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autor principal: Walter R Tschinkel
Formato: article
Lenguaje:EN
Publicado: Public Library of Science (PLoS) 2012
Materias:
R
Q
Acceso en línea:https://doaj.org/article/eb44c3e2debf438aa22e255027f4bc68
Etiquetas: Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
id oai:doaj.org-article:eb44c3e2debf438aa22e255027f4bc68
record_format dspace
spelling oai:doaj.org-article:eb44c3e2debf438aa22e255027f4bc682021-11-18T07:14:18ZThe life cycle and life span of Namibian fairy circles.1932-620310.1371/journal.pone.0038056https://doaj.org/article/eb44c3e2debf438aa22e255027f4bc682012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22761663/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203In Namibia of southwestern Africa, the sparse grasslands that develop on deep sandy soils under rainfall between 50 and 100 mm per annum are punctuated by thousands of quasi-circular bare spots, usually surrounded by a ring of taller grass. The causes of these so-called "fairy circles" are unknown, although a number of hypotheses have been proposed. This paper provides a more complete description of the variation in size, density and attributes of fairy circles in a range of soil types and situations. Circles are not permanent; their vegetative and physical attributes allow them to be arranged into a life history sequence in which circles appear (birth), develop (mature) and become revegetated (die). Occasionally, they also enlarge. The appearance and disappearance of circles was confirmed from satellite images taken 4 years apart (2004, 2008). The frequency of births and deaths as a fraction of the total population of circles allowed the calculation of an approximate turnover rate, and from this, an estimate of circle lifespan. Lifespan appeared to vary with circle size, with small circles averaging about 24 years, and larger ones 43-75 years. Overall lifespan averaged about 41 yr. A second, independent estimate of lifespan was made by revisiting circles 2 to 9 years after their clear status had been confirmed. This resulted in a lifespan estimate of about 60 years. Any causal explanation of fairy circles must include their birth, development and death, their mean lifespan and the variation of their features under different conditions.Walter R TschinkelPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 6, p e38056 (2012)
institution DOAJ
collection DOAJ
language EN
topic Medicine
R
Science
Q
spellingShingle Medicine
R
Science
Q
Walter R Tschinkel
The life cycle and life span of Namibian fairy circles.
description In Namibia of southwestern Africa, the sparse grasslands that develop on deep sandy soils under rainfall between 50 and 100 mm per annum are punctuated by thousands of quasi-circular bare spots, usually surrounded by a ring of taller grass. The causes of these so-called "fairy circles" are unknown, although a number of hypotheses have been proposed. This paper provides a more complete description of the variation in size, density and attributes of fairy circles in a range of soil types and situations. Circles are not permanent; their vegetative and physical attributes allow them to be arranged into a life history sequence in which circles appear (birth), develop (mature) and become revegetated (die). Occasionally, they also enlarge. The appearance and disappearance of circles was confirmed from satellite images taken 4 years apart (2004, 2008). The frequency of births and deaths as a fraction of the total population of circles allowed the calculation of an approximate turnover rate, and from this, an estimate of circle lifespan. Lifespan appeared to vary with circle size, with small circles averaging about 24 years, and larger ones 43-75 years. Overall lifespan averaged about 41 yr. A second, independent estimate of lifespan was made by revisiting circles 2 to 9 years after their clear status had been confirmed. This resulted in a lifespan estimate of about 60 years. Any causal explanation of fairy circles must include their birth, development and death, their mean lifespan and the variation of their features under different conditions.
format article
author Walter R Tschinkel
author_facet Walter R Tschinkel
author_sort Walter R Tschinkel
title The life cycle and life span of Namibian fairy circles.
title_short The life cycle and life span of Namibian fairy circles.
title_full The life cycle and life span of Namibian fairy circles.
title_fullStr The life cycle and life span of Namibian fairy circles.
title_full_unstemmed The life cycle and life span of Namibian fairy circles.
title_sort life cycle and life span of namibian fairy circles.
publisher Public Library of Science (PLoS)
publishDate 2012
url https://doaj.org/article/eb44c3e2debf438aa22e255027f4bc68
work_keys_str_mv AT walterrtschinkel thelifecycleandlifespanofnamibianfairycircles
AT walterrtschinkel lifecycleandlifespanofnamibianfairycircles
_version_ 1718423763497779200