Mysterious circles in the Namib Desert: review of hypotheses on their origin
Circular, slightly concave depressions, devoid of vegetation and often surrounded by a fringe of tall grasses occur in a broken belt in the pro-Namib zone of the west coast of southern Africa. Several hypotheses have been proposed to explain the origin of these so-called fairy circles. The most impo...
Saved in:
Published in | Journal of arid environments Vol. 57; no. 4; pp. 467 - 485 |
---|---|
Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
01.06.2004
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Circular, slightly concave depressions, devoid of vegetation and often surrounded by a fringe of tall grasses occur in a broken belt in the pro-Namib zone of the west coast of southern Africa. Several hypotheses have been proposed to explain the origin of these so-called fairy circles. The most important of these relate to areas of localized radioactivity; termite activity; or allelopathic compounds released by dead
Euphorbia damarana plants. No evidence of increased radioactivity could be detected in soil samples collected from these sites. Although termites occur at these localities no evidence was found to link termite activity directly to the formation of barren patches. Bioassays conducted on soil collected from the centre of the barren patch clearly demonstrated an inhibition of plant growth, while soil collected from the edge of the barren patch had a stimulatory effect on plant growth. No indication of growth inhibition was found in soil collected beneath
E. damarana plants. At this stage none of the proposed hypotheses can satisfactorily explain the origin of the fairy circles. |
---|---|
Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0140-1963 1095-922X |
DOI: | 10.1016/S0140-1963(03)00111-3 |