Effect of land use on anuran species composition in north-eastern KwaZulu-Natal, South Africa

Abstract

Human induced landscape change is a major driver of biodiversity of loss and landscape homogeneity. North-eastern KwaZulu-Natal, South Africa, is an area of high biodiversity as well as increased human urban development and changing land use. We assessed the effects of various agricultural land uses on anuran species composition within this area. Anuran species composition was examined over three strata namely: land use, season and habitat. Land use types surveyed were eucalyptus (Eucalyptus sp.) plantations (n = 4), sugar cane (Saccharum officinarum) farms (n = 4) and conservation areas (n = 5). Sampling was split into three sampling periods: early (Oct–Nov), mid (Dec–Jan) and late (Feb–Apr). Each property was sampled once during each of these periods, and three habitat types were sampled: open water bodies, wetland areas and grassland/woodland complexes. Pit-fall traps with drift-net fences and vocalizations were used to identify anuran species. Mean number of anuran species found on conservation, sugar and eucalyptus sites were 13 ± 6.6; 4 ± 1.3; and 3 ± 1.4 respectively. Correspondence Analysis (CA) produced eigen values of 0.526, 0.485, 0.435 and 0.363 for the first four axes respectively. These axes accounted for 41.5% of the total inertia. Sites within the CA were classified according to land use, season and habitat. Sugar and eucalyptus plantations had lower variation between sites, and low variation in habitat type. Low anuran species richness in the eucalyptus and sugar cane areas is most likely lack of suitable habitat for species that are either totally dependent or totally not dependent on water bodies. Absence of Hyperolius marmoratus and Amietophrynus gutturalis was the factor defining the first division (eigen value 0.498) produced by the TWINSPAN analysis. The two groups produced were significantly different in terms of land use, habitat and season. Land use, particularly sugar cane and agroforestry plantations, had an impact on anuran species presence and composition, and needs to be considered in management for their conservation.