Brushpiles and dung as rehabilitation patches: effect on soil resources in degraded succulent thicket, Eastern Cape, South Africa

Abstract

A substantial portion of the Thicket Biome in the Eastern Cape has been transformed by overgrazing. An experimental rehabilitation study of degraded succulent thicket was initiated to determine whether increasing the patchiness on the landscape would result in an increase in soil resources. Five types of treatments were used for the rehabilitation trials, namely: piles of black rhinoceros (Diceros bicornis) dung placed so as to mimic rhino latrines; Portulacaria afra brushpiles; brushpiles of woody Thicket species; brushpiles of woody Thicket species over-sown with seed; and the control (area left unchanged). Measurement occurred before and three years after treatment and change was related to an untransformed reference site. All of the treatments did increase the litter in the patches, which resulted in an increase in soil organic content especially in the top 3cm of soil. All of the rehabilitation patches were successful in accumulating basic elements (pH and electrical conductivity results) as well as available phosphorus. The dung treatment had the greatest effect on the soil resources underneath and surrounding the patches. The dung treatment significantly increased the electrical conductivity as well as the available phosphorus and available organic nitrogen. The rehabilitation trial has shown that by increasing the patchiness of degraded areas in succulent thicket it is possible to initiate "islands of fertility".