Coastal dune topography as a determinant of abiotic conditions and biological community restoration in northern KwaZulu-Natal, South Africa

• Published in: Landscape and ecological engineering 2014-01, Vol.10 (1), p.17-28
• Main Authors: Ott, Theresia, van Aarde, Rudi J
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Biomedical and Life Sciences; canopy; Civil Engineering; Conservation, protection and management of environment and wildlife; Diplopoda; Dunes; ecological restoration; Elevation; Environmental conditions; Environmental Management; Environmental restoration; forests; Fundamental and applied biological sciences. Psychology; Geomorphology; Landscape Ecology; Landscape/Regional and Urban Planning; Life Sciences; Light intensity; Living conditions; Microhabitats; mining; Nature Conservation; Nutrient availability; Original Paper; Plant Ecology; Relative humidity; soil; Soil nutrients; Soils; species diversity; Species richness; temperature; Topography; trees; Woody plants
• ISSN: 1860-1871; 1860-188X
• DOI: 10.1007/s11355-013-0211-1

Topography is rarely considered as an independent goal of restoration. However, topography determines microenvironmental conditions and hence living conditions for species. Restoring topography may therefore be an important first step in ecological restoration. We aimed at establishing the relative importance of topography where coastal dunes destroyed by mining are rebuilt as part of a rehabilitation program. We assessed the response of (1) microclimatic and soil conditions, and (2) woody plant and millipede species richness and density, to location-specific topographic profiles. We enumerated the topographic profile using variables of dune morphology (aspect, elevation, and gradient) as well as relative position on a dune (crest, slope, and valley). Temperature, relative humidity, and light intensity varied with aspect, elevation, gradient, and position. However, regeneration age was a better predictor of soil nutrient availability than these topographic variables. Age also interacted with topographic variables to explain tree canopy density and species richness, as well as millipede species richness. The density of keeled millipedes (forest specialists) was best explained by topographic variables alone. The transient nature of these new-growth coastal dune forests likely masks topography-related effects on communities because age-related succession (increasing structural complexity) drives the establishment and persistence of biological communities, not habitat conditions modulated by topography. However, our study has shown that the microhabitats associated with topographic variability influence specialist species more than generalists.