Termite species and functional diversity as determined by vegetation and edaphic characteristics in a savanna ecosystem

Abstract

Savanna ecosystems support a diversity of biota and are influenced by vegetation and edaphic characteristics, shaping resident communities. This study was carried out at Mlawula nature reserve, a protected savanna ecosystem to determine impacts of vegetation and edaphic characteristics on termite species and functional diversity, as well as their activity. Termites were sampled from November 2017 to March 2018 in two habitat types, i.e. encroached and non-encroached by Dichrostachys cinerea over five months. Twelve genera were collected over the study period, dominated by Microtermes sp. Termite species diversity and populations were significantly between habitat types, with higher numbers and species in non-encroached sites. Four functional groups (FG) were collected from both habitat types, with FGII being the most dominant group in both and no significant differences in FG diversity between the habitat types. Of the vegetational and edaphic variables measured, only canopy cover was significantly different between habitat types and was higher in encroached sites. Intensity and frequency of attack were significantly higher in non-encroached sites, indicating a decline in termite activity in encroached sites. Results indicated that, with the exception of canopy cover, vegetational and edaphic characteristics are not affected by increased woody vegetation invasion within the system assessed. However, due to reduction in termite diversity and activity, increased woody vegetation invasion is a threat to termites and associated ecosystem services they provide. The investigation provided information at both community and ecosystem level for the savanna assessed on the need for insect conservation both within protected areas and surrounding landscapes. Since the study suggested that termite populations and associated activity could be reduced due bush encroachment, monitoring of the impacts of increasing woody plant invasions is essential for insect conservation and maintenance of savanna ecosystem function and heterogeneity.