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Dune mobility and vegetation cover in the Southwest Kalahari desert
Author(s) -
Wiggs Giles F. S.,
Thomas David S. G.,
Bullard Joanna E.,
Livingstone Ian
Publication year - 1995
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/esp.3290200604
Subject(s) - aeolian processes , vegetation (pathology) , erosion , geology , sediment , vegetation cover , sand dune stabilization , limiting , hydrology (agriculture) , physical geography , environmental science , geomorphology , ecology , geography , grazing , engineering , medicine , mechanical engineering , geotechnical engineering , pathology , biology
As part of a wider project investigating the palaeoenvironmental significance of partially vegetated linear dunes in the southwest Kalahari, data collected in the latter part of 1992 concerning dune movement and vegetation cover suggest that sediment transport is occurring on some dune surfaces, and that the majority of surface activity occurs on the crests and upper slopes of the dunes. The data suggest that the limiting variables on surface sediment movement vary on different parts of a dune. On interdunes and lower dune slopes the primary limiting variable is available wind energy, while on dune crests and upper slopes it is vegetation cover. Ground cover by litter has much greater importance in protecting the surface sediment from erosion than rooted vegetation. From individual data points, no evidence is found to support a threshold vegetation cover below which sediment movement occurs. Rather, a gradient of activity is suggested whereby a reduction in vegetation cover increases the potential for sediment movement and surface change. However, dunes with differing amounts of mean vegetation cover display differing degrees of surface activity, and at this scale, a vegetation cover threshold in the region of 14 per cent may be recognized.