家禽、水産および野生生物科学
オープンアクセス

概要

An Assessment of Impacts of African Elephants (Loxodonta africana) on the Structure of Mopane (Colophospermum mopane) in the North Eastern Lake Kariba Shore, Zimbabwe

Mudavanhu Simbarashe and Mudavanhu Farai

A study on impacts of African elephants (Loxodonta africana) on the structure of C. mopane was done on the north eastern Lake Kariba shore, Zimbabwe. The objectives of the study were to determine the structure and abundance of C. mopane, determine the levels of elephant induced damage on C. mopane along a distance gradient from the lake and to determine the relationship between elephant induced damage on C. mopane trees and distance from the north eastern Lake Kariba shore. C. mopane trees were sampled in May 2013. Four belt transects were demarcated extending from the lake towards the ZESA pylons. Eight plots measuring 20 m x 30 m were systematically placed at 100 m, 500 m, 1000 m and 2000 m distances from the lake shore within each belt. C. mopane variables, that is, tree height, basal area, tree density, shrub density, number of stems per plant, density of damaged plants and number of dead trees were recorded within each plot. Damage was also assessed and rated depending on the intensity of damage. A total of 479 C. mopane trees were sampled in 32 plots. Data was analysed using STATISTICA Version 7 Results from Kruskal-Wallis ANOVA test (KWH test), indicated that Height (P=0.5423), basal area (P=0.9463), tree density (P=0.2465), shrub density (P=0.3027), number of stems per plant (0.7503, density of damaged plants (P=0.1802) and density of dead trees (P=0.4603) were not significantly different across all distances from the lake. The results also indicated no significant difference in the level of damage (P=0.8050) across all distances from the lake. PCA indicated that trees were densely populated in areas close to the lakeshore (100 m and 500 m) and it is within this area where the highest number of damaged and dead trees was recorded. HCA showed that plots within 2000 m recorded the highest average sapling density, plots within 1000 m recorded the highest average tree height and shrub density and plots within 100 m recorded the highest of density of damaged trees and basal area. Findings from linear regression showed that distance from water create an herbivory gradient of C. mopane utilization though the herbivory gradient might not lead to overall degradation of C. mopane. Management should focus on maintaining herbivore populations within ranges that does not lead to C. mopane woodland degradation.