An assessment of a vlei ecosystem restoration process: Monavale Vlei, Harare

Abstract

Vegetation composition and diversity, soil physical and chemical parameters and primary productivity are important components of a wetland ecosystem recovery process. A comparative analysis of key indicators of ecosystem recovery from agricultural disturbance over a ten year period on part of the Monavale Vlei was made. Field data were collected during the month of March 2015. Results showed a significant increase in herbaceous species diversity over the ten year period. Nitrogen, organic carbon, moisture, silt and clay content on the former crop land did not vary significantly ((P>0.05) over the same period. Significant differences in soil chemical characteristics were, however, observed between former cultivated sites and uncultivated sites during the period 2006 and 2015 (P˂0.05). The proportion of land under the grassland land class increased from 23% in 2004 to 84% in 2013. Analysis of Normalised Difference Vegetation Index (NDVI) on former cultivated sites showed a significant increase (95% confidence level) in net primary production (NPP). The initial drop in NPP on former crop land between 2004 and 2007 was followed by gradual increases in 2010 and 2013. Results of the study indicate a positive progression towards restoration of this part of Monavale Vlei.