Conservation Refugium Value of a Large Mesa for Grasshoppers in South Africa |
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Authors: | Solomon Gebeyehu Michael J Samways |
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Institution: | (1) Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, 0002, South Africa;(2) Department of Entomology, University of Stellenbosch, Private Bag X1, Matieland, 7602, South Africa |
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Abstract: | A 3-year study was undertaken on and around a prominent South African mesa to determine its role for grasshoppers in a sea
of grazed flatlands. The number of grasshopper species and individuals on the summit, slopes and flatlands varied significantly
in relation to measured environmental variables. The summit, through inaccessibility to livestock grazing, was effectively
a conservation refugium for one highly responsive grasshopper species, Orthochtha dasycnemis. There was no significant difference in species richness between years of sampling, although there were significant variations
in grasshopper abundance between years. The difference in rainfall between years was significant and appeared to be the key
factor influencing grasshopper population dynamics. This study clearly shows that a mesa can act as a conservation island
and refugium supporting an insect assemblage that would be otherwise altered by heavy livestock grazing on the surrounding
flatlands. This summit assemblage was strongly linked with those on the slopes, and is determined by low grazing intensity
and associated soil and vegetation structure. |
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Keywords: | Conservation refugium Elevation Grasshoppers Mesa South Africa |
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