Regional land-use impacts affecting avian richness patterns in Southern Africa-insights from historical avian atlas data

Abstract

Biodiversity conservation is a challenge within developing regions of the world. Landscape heterogeneity is largely directed by interconnected economic and social systems, which are largely driven by political, communal, and private control of the land estate. There is increasing evidence that areas of high species richness may coincide with dense human settlement. Influences of landscape pattern, human impact, and divergent past political land management on functional groups of bird species richness were examined in KwaZulu–Natal, South Africa. The functional groups included species of breeding, non-breeding, generalist, and specialist birds. A database of land-use/land-cover (LULCC) and human impact indicators was used to develop relationships and infer historic changes in bird richness derived from two censusing periods (1975–1979 and 1988–1992). The objective was to examine richness and compare relationships based on analyses using land management regions, avifaunal zones and socio-economic regions. Paired and two-sample t-tests documented differences in richness among land management regions and between regions over time. Landscape metrics, LULCC proportion, and other human impact variables were examined using Monte Carlo permuted multiple regressions to develop relationships for bird richness groups. Significant increases in bird group richness were shown between survey periods, as well as differences between land management regions. The statistical models explained 22–79% of variation in bird richness among avifaunal zones by functional group, and 32–99% of variation in bird richness among the socio-economic regions. The majority of the relationships were explained by LULCC proportion rather than landscape metrics denoting spatial arrangement. The analysis concludes that there have been significant increases in bird richness apparently related to land-use development during the study period. The apparent increase in richness may be due to maintenance of original vegetation-specific species in untransformed fragments in highly transformed areas combined with species that exploit transformed habitats well in the transformed areas. It is concluded that research on the interface between biogeography and human development should be seen as a perquisite for conservation assessments in developing regions of the world.