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Eco-estates: diversity hotspots or isolated developments? Connectivity of eco-estates in the Indian Ocean Coastal Belt, KwaZulu-Natal, South Africa

Alexander, Jarryd, Smith, David A. Ehlers, Smith, Yvette C. Ehlers, Downs, Colleen T.
Ecological indicators 2019
biodiversity, birds, climate change, coasts, environmental indicators, forests, functional diversity, habitats, immigration, land cover, land use change, landscapes, population growth, riparian areas, rivers, urbanization, Indian Ocean, South Africa
Population expansion and land transformation reduce biodiversity, potentially reducing environmental functionality. These effects are evident globally, and specifically in KwaZulu-Natal (KZN), South Africa, where land cover is being transformed for urbanisation. However, much of the urbanised areas incorporate differing levels of urban greening, which is improving local species and functional diversity. In recent years, a new form of urban greening in the form of eco-estate development has increased, which improves biodiversity and functional diversity. However, it has not yet been determined whether these eco-estates are connected to one another and the surrounding natural landscapes, allowing for natural species’ colonisation, immigration and dispersal. In this study, we assessed whether eco-estates along the coast of KZN were ecologically connected to a) one another, and b) the surrounding natural landscape. Using a hybrid Least-cost Pathway/Ecological Circuit Theory approach, we modelled habitat suitability and dispersal requirements of a forest-specialised bird species in an effort to provide future development and management plans for eco-estates. Connectivity throughout coastal KZN was evident, with increased connectivity in areas of natural and urban indigenous forest and coastal thicket/dense bush and river systems (riparian zones), within which existing eco-estates were subsequently developed. Eco-estates were well connected to one another and surrounding natural landscapes, emphasising their importance as patches containing endangered indigenous forest and unprotected coastal thicket/dense bush and of increased species and functional diversity, improving local ecosystem functioning. We recommend that eco-estate development primarily focus on areas which have previously been transformed, to increase natural land cover. The intention to preserve, rehabilitate, and conserve natural land cover is fundamentally important if development is to take place within and surrounding areas of high connectivity to assist in increasing and conserving suitable habitats, improving functionality and connectivity in KZN, and assisting in offsetting the deleterious effects of future climate change.