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SEPG 2132 Date Awarded 2003
The structure of grassland Orthopteran communities in the Nyika National Park, Malawi: the influence of burning and vegetation
Karim Vahed
Abstract
Orthoptera can be excellent indicators of grassland naturalness and have been used to monitor landscape use and degradation. The Orthoptera of the Nyika National Park, Malawi have been relatively little studied. The principal aim of this project was to inventory the grassland Orthoptera of the Nyika plateau, Malawi (10o 30’ S; 33o 50’ E.), focussing on the grasshoppers (Acridoidea) and bushcrickets (Tettigonioidea). Other aims were to examine the effect of, or relationship between, time since burning, vegetation height, vegetation percentage cover, altitude and orthopteran species richness and diversity (Shannon-Weiner’s diversity measure). Sixteen different sites were surveyed, which had been burned either 10 days (n = 4 sites), one month (n = 4), one year (n = 4) or two years (n = 4) previously. At each site, orthoptera were surveyed within a 10 x 10 m quadrat and the vegetation (dominant species, height and percentage cover) were sampled within 2 x 2 m quadrats. GLM analysis revealed that the percentage cover of grass had a significant, positive effect on orthopteran species richness and diversity. Conversely, the percentage of bare earth had a significant negative effect on orthopteran species richness. Time since burning also had a significant effect on orthopteran species richness and diversity: the greatest species richness and diversity was found in sites that had not been burned for 2 years. There was, however, no significant effect of time since burning on the density of individuals, which suggests that burnt areas are re-colonised rapidly.
Full report: SEPG2132
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