Response of arthropod communities to plant-community rehabilitation efforts after strip mining on the semi-arid west coast of South Africa

Abstract

Strip mining in arid ecosystems causes extreme ecological destruction that may take decades to recover. The present study examined the effect of different plant-community rehabilitation treatments on arthropods after strip mining in the arid Namaqualand region of South Africa. Vegetation cover and plant species richness were significantly lower at all rehabilitated sites compared with those at a reference site. Arthropod species richness did not differ amongst the different treatments and the reference site. Except for the most recently rehabilitated site, arthropod abundance in all guilds was higher at all treatments compared with that of the reference site. Overall arthropod abundance was positively correlated to plant cover and negatively correlated to plant species richness, but these vegetation characteristics had no effect on arthropod species richness. This may be explained by a high cover of pioneer plants at the rehabilitated sites, which offer ample food for generalist arthropod taxa. Arthropod community composition differed significantly between treatments. We demonstrate that rehabilitation of ecosystem function after mining in arid systems is a lengthy process, even after implementation of intensive rehabilitation protocols. We also show that arthropod communities provide additional insights into the level of ecosystem recovery otherwise obscured when only considering plant community data.

Keywords: biodiversity conservation, insects, rehabilitation, Succulent Karoo