Grass species diversity response to brush packing in semi-arid rangelands of South Africa

Most semi-arid savannahs in South Africa are being degraded by bush encroachment, resulting in a decline in biodiversity. Four restoration treatments consisting of bush clearing, brush packing, reseeding and a combination of clearing, reseeding and brush packing were tested. Grass diversity was measured in a communal and con-servation area using the difference between the baseline year (2017) and two years after restoration (2019). The effect of brush packing versus non-brush packing was further assessed analysing indicator species and the composition of grass species communities. The brush packing and reseeding had a less pronounced effect on grass richness and diversity at the conservation area, however a large effect on grass richness (p < 0.05) at the communal area. The results suggest that brush packing promotes grass diversity under high grazing pressure in communal areas compared to conservation areas. Species evenness was positively affected by brush packing at the communal area, while abundance was not significantly affected by the treatments. Furthermore, the results showed that the grass composition was dissimilar between brush packed and un-brush packed treatments, in the communal area. A higher number of decreasers and perennial grass species were identified in the brush packing treatments compared especially to the communal area.