Premium
The role of biota in the initiation and growth of islands on the floodplain of the Okavango alluvial fan, Botswana
Author(s) -
McCarthy T. S.,
Ellery W. N.,
Dangerfield J. M.
Publication year - 1998
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/(sici)1096-9837(199804)23:4<291::aid-esp844>3.0.co;2-a
Subject(s) - epigeal , floodplain , alluvium , overbank , alluvial fan , geology , biota , flooding (psychology) , hydrology (agriculture) , ecology , fluvial , geomorphology , geochemistry , sedimentary rock , biology , geotechnical engineering , structural basin , psychology , psychotherapist
A group of islands of varying size on the floodplain of the Okavango alluvial fan, were studied to establish the processes which lead to the initiation and growth of islands. It was found that islands are initiated by the mound‐building activities of the termite Macrotermes michaelseni . These termites import fine grained materials to use as a mortar for the construction of epigeal mounds. Their activities create a topographic feature, raised above the level of seasonal flooding, and also change the physical properties and nutrient status of the mound soil. Shrubs and trees are able to colonize these mounds, which results in increased transpiration. As a result, precipitation of calcite and silica from the shallow ground water occurs preferentially beneath the mounds, resulting in vertical and especially lateral growth, causing island expansion. © 1998 John Wiley & Sons, Ltd.