Warning: file_get_contents(https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=26510015
&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 215
Deprecated: Implicit conversion from float 211.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 211.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Warning: imagejpeg(C:\Inetpub\vhosts\kidney.de\httpdocs\phplern\26510015
.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 PLoS+One
2015 ; 10
(10
): e0140099
Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
Experiments Testing the Causes of Namibian Fairy Circles
#MMPMID26510015
Tschinkel WR
PLoS One
2015[]; 10
(10
): e0140099
PMID26510015
show ga
The grasslands on the sandy soils of the eastern edge of the Namib Desert of
Namibia are strikingly punctuated by millions of mostly regularly-spaced circular
bare spots 2 to 10 m or more in diameter, generally with a margin of taller
grasses. The causes of these so called fairy circles are unknown, but several
hypotheses have been advanced. In October 2009, we set up experiments that
specifically tested four hypothesized causes, and monitored these 5 times between
2009 and 2015. Grass exclusion in circles due to seepage of subterranean vapors
or gases was tested by burying an impermeable barrier beneath fairy circles, but
seedling density and growth did not differ from barrier-less controls. Plant
germination and growth inhibition by allelochemicals or nutrient deficiencies in
fairy circle soils were tested by transferring fairy circle soil to artificially
cleared circles in the grassy matrix, and matrix soil to fairy circles (along
with circle to circle and matrix to matrix controls). None of the transfers
changed the seedling density and growth from the control reference conditions.
Limitation of plant growth due to micronutrient depletion within fairy circles
was tested by supplementing circles with a micronutrient mixture, but did not
result in differences in plant seedling density and growth. Short-range
vegetation competitive feedbacks were tested by creating artificially-cleared
circles of 2 or 4 m diameter located 2 or 6 m from a natural fairy circle. The
natural circles remained bare and the artificial circles revegetated. These four
experiments provided evidence that fairy circles were not caused by subterranean
vapors, that fairy circle soil per se did not inhibit plant growth, and that the
circles were not caused by micronutrient deficiency. There was also no evidence
that vegetative feedbacks affected fairy circles on a 2 to 10 m scale.
Landscape-scale vegetative self-organization is discussed as a more likely cause
of fairy circles.