Dynamics of fallow secondary succession pathways and prospects of ecosystem recovery in semi-arid agricultural landscapes

Abstract

ABSTRACT This study investigates the dynamics of secondary succession pathways and analyses the prospects of ecosystem recovery on two soil types in the semi-arid mid-Zambezi valley, northern Zimbabwe. Thirty-five fallow plots of different ages, ranging from one to twelve years since abandonment and twenty 0.09 ha plots of mature woodland were sampled. The results showed observable changes in vegetation features along the chronosequences of recovering fallow plots. There were significant (p<0.05) relationships between fallow age and tree density and tree diameter at breast height (DBH) with an observable decrease in tree diversity with increasing fallow age. The dominant species within the recovering fallow vegetation were different from the defining species within the natural woodlands. Acacia tortilis subsp. spirocarpa exclusively dominated the vegetation in older fallows and it was less clear whether typical woodland species would regain dominance. Therefore, management efforts may have to focus on initiatives aimed at conserving existing woodlands, which will be vital for the maintenance of defining species.