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

Quantification of landform heterogeneity and its relationship with ecological patterns in broad-scale post-mine rehabilitation

“…As a result, landforms affect distribution, growth and diversity of biota. The relationships between landform attributes and ecological patterns are well demonstrated in published literature (Swanson et al, 1988, Larkin et al, 2006, Solon et al, 2007, Ott and van Aarde, 2014. In light of this, this research aims to investigate if the post-mine rehabilitation landscape exhibits relationships between landform heterogeneity and ecological patterns similar to those observed in natural landscapes.…”

“…In older sites (11 to 25 years) it was the abundances of canopy and understorey species that correlated with topographic gradients, while in the oldest rehabilitation areas, such relationships existed only with elevation (Ott and van Aarde, 2014). Takyu et al (2003) reported that initial substrate conditions may often be the stronger primary influence differentiating forest ecosystems, and while Silva et al (2008) found species richness in secondary forest fragments in Brazil was not a function of slope location, average aspect or slope, topography still played an indirect role as altitude was shown to influence species richness.…”

“…Enoki (2003) concluded that topographic heterogeneity on a small spatial scale contributed to high species diversity in a subtropical evergreen broad-leaved forest. In a South African example of rehabilitation after sand mining through a dune system Ott and van Aarde (2014) found that in those rehabilitated sites less than 10 years old, canopy species richness, but not their abundance, was explained by variance in topographic characteristics.…”

“…For example, in a study in India by Raizada and Juyal (2010), the lower slopes, which had more ambient conditions, showed profuse regeneration of exotic and opportunistic species, while the native species occupied the harsher higher and middle slopes and reached a natural stable climax. In a rehabilitated dune system following mineral sands mining, a higher density of woody tree species was found on the steeper slopes (Ott and van Aarde, 2014). An assessment of the distribution of canopy trees against the topographic characteristics (slope steepness and configuration) by Enoki (2003), revealed a few insights useful for rehabilitation planning.…”

“…Variance in altitude influences soil properties and hence the nutrient conditions and root biomass (Gibson, 1988). Topography creates a gradient of water and nutrient availability in the soil (Zak et al, 1991, Hirobe et al, Goro et al, 1997 and species composition is known to change with topographic gradient (Ott and van Aarde, 2014). Variation in abiotic factors with topographic gradients may reflect in changes in species composition and species distribution (Chen et al, 1997, Oliveira-Filho et al, 1998.…”