The Epigeal and Epiphytic Hemipteran Assemblages as Indicators of Rehabilitation Success on Ash Disposal Sites at Hendrina Power Station.

Abstract

Hemiptera portrays many of the characteristics of successful bioindicators, however hemipterans have also shortcomings in this regard. Few studies have been conducted on the bio-indicative value of hemipteran species in South Africa. This study was conducted at Hendrina Power Station (Mpumalanga, South Africa) and entails a preliminary study on the possible indicative value of hemiptera as possible bioindicators during succession on rehabilitated ash dams. On the ash dams 61 species in 13 families were recorded compared to the 47 species in 16 families recorded in natural grassland. The natural grassland represented the most advanced succesional stage. The early stage of rehabilitation was characterized by low vegetation cover, low organic matter and high gravel content within the soil. Mainly pioneer hemipteran species were recorded during the first stages of rehabilitation probably utilizing pioneer vegetation as herbivores. Relatively low species diversity was also evident during this stage. The second stage of rehabilitation was characterized by more stable plant communities, high vegetation cover and high organic matter content resulting in higher hemipteran species diversity. Although lower species diversity was expected on the rehabilitated ash dams than in the natural veld, this was not confirmed from the results. This was discussed in this study and indicated further research opportunities. Multivariate ordinations were used to investigate possible correlations of hemipteran assemblages with edaphic characteristics. Significant correlations were found between hemipteran species richness and clay content, pH and organic matter.