Comparative analysis of the early growth performance of indigenous Acacia species in revegetating Trojan Nickel Mine tailings in Zimbabwe

Abstract

Indigenous Acacia species are preferred in mine dump revegetation because of their ability to colonize hostile environments, enhance soil fertility and meet the livelihood and cultural needs of local communities. This study compared early growth performance of three indigenous Acacia sp. namely Acacia gerrardii, Acacia karroo and Acacia polyacanthaestablished on nickel mine tailings amended with top soil, sewage sludge, and compound fertilizer. Growth performance in height and root collar diameter (RCD) were measured monthly using a meter rule and a vernier caliper respectively and survival was determined at the end of a six-months period. A completely randomized block design with 12 treatments replicated three times was used. Survival and relative growth rates in height and RCD (RGRh and RGRd), were tested for significant differences among treatments through analysis of variance using SPSS for Windows Version 15.0 (2006). Overall, there were no significant differences (P>0.05) in survival among the Acacia species but variation in survival (P<0.05) was observed among amendments. Species growth performance also varied (P < 0.05) among amendment materials and across species. It was concluded that all the three species can be used in revegetation of nickel mine tailing dumps.   Key words: Indigenous, Acacia, nickel tailings, survival, growth performance, amendments