Short term soil and vegetation recovery after Acacia mearnsii removal in Vhembe Biosphere Reserve, South Africa

Abstract

Short term monitoring of soil and vegetation recovery following alien plant removal is required to reveal how ecological restoration is progressing. This study examined the recovery of soil physical properties and vegetation following Acacia mearnsii removal at Zvakanaka farm in Limpopo Province, South Africa. Soil and vegetation measurements were conducted in paired cleared, invaded and natural sites on 10 x 10 m plots. Results of the study show significantly (P < 0.001) higher soil moisture content in invaded and natural compared to cleared sites. Soil penetration was significantly (P < 0.001) higher in cleared than invaded and natural sites. Both infiltration rate and hydraulic conductivity showed no significant (P > 0.05) difference between the three sites. Strongly repellent soils were recorded in cleared sites only. Results showed a significant (P < 0.05) increase in measured diversity indices (species richness, Shannon-Wiener, Simpson’s and evenness index) in cleared and natural than in invaded sites. However, most secondary woody invasive alien plants were recorded in cleared sites. The study concludes that A. mearnsii clearing triggers varying changes in soil physical properties. Although native plants are present in cleared sites, recovery may be hampered by the growth of secondary woody invasive alien plants.