Plant diversity patterns of domestic gardens in five settlements of South Africa

Abstract

As urbanisation increases globally, domestic gardens are becoming increasingly important in terms of ecosystem service provisioning, biodiversity conservation and human health and wellbeing. Individually gardens are small, but collectively they comprise substantial proportions of both rural and urban areas and consequently they provide green corridors for the movement of wildlife through the urban matrix. The aim of this thesis was to collect and compare information on the flora present in the domestic gardens of five different settlements across South Africa (Tlhakgameng, Ganyesa, Ikageng, Potchefstroom and Roodepoort) and to determine if the garden management practices and socioeconomic status of householders influences the plant species richness and diversity of these domestic gardens. Additionally, the plant diversity patterns of different land-use types were compared with those of the sampled domestic gardens within each settlement. In comparison with other land-use types, domestic gardens contribute greatly to the overall species richness of both urban and rural settlements. A total of 1424 species were recorded in 598 sample sites for all five settlements and 1524 species were recorded in 256 domestic gardens. The majority of species recorded in the domestic gardens were alien cultivated, while the natural areas contained mostly indigenous species in all five settlements. However, despite the fact domestic gardens provide habitats for biodiversity conservation and support the livelihoods of householders, by introducing and spreading alien species, gardens could threaten natural ecosystems and their services. Nevertheless, domestic gardens have the potential to provide numerous ecosystem services, but this greatly depends on the management decisions, socioeconomic status and personal preferences of the householder. The results of this study showed that the species composition and richness in domestic gardens was influenced by the management activities and socioeconomic status of the householders. In most of the settlements, the floristic diversity increased as the frequency and intensity of management practices increased. Furthermore, the species richness of domestic gardens increased from a low to high SES. This study contributes to our knowledge of the different types of green infrastructure (represented by various land-use types) present in five different settlements in South Africa, their species composition and diversity. This type of research is especially important when considering the rate of urbanisation in South Africa. By understanding the contribution that different land-use types, especially domestic gardens, make to the overall diversity of an urban or rural settlement will aid policy makers and municipal governments in properly managing these areas and ensuring the provisioning of ecosystem services in an urbanising South Africa. Future domestic garden studies in South Africa should attempt to identify the motivations behind gardening in SA, the influences of culture on gardening, promote environmentally-friendly gardening practices, limit the spread of invasive species, promote the cultivation of indigenous species and encourage people to protect biodiversity in cities and towns. If the current rate of urbanisation continues, gardens may become the only source of interaction with nature that some people will have on a daily basis