Urban ecologists study many interactions between living organisms (plants, animals, micro- organisms, humans) and between the organisms and the non-living environment (soil, air, water) in cities, towns and settlements.
Why? Because urban nature fulfils important functions (eco- system services) “for free” that improve human health and well- being. Some examples are food – urban agriculture is vital for food security and habitats for broad biodiversity, including endangered species and beneficial species like pollinators. Plants regulate air quality and climate and remove pollutants and carbon dioxide. They also stabilise slopes and prevent soil erosion. Wetlands control floods and remove effluent from waste water. Urban nature also has several physical, aesthetic, spiritual and psychological benefits for urban residents. Unfortunately, it also has adverse effects, like allergenic pollen, financial costs due to tree branches and roots damaging structures and much more. The truth is, however, urban nature has more advantages than disadvantages, but only if it is protected and well-planned, designed and managed in a way that involves all relevant stakeholders. Unfortunately, this does not happen in most cities in South Africa! Urban nature is also under constant pressure from development. Many local governments in South Africa have meagre budgets to maintain and protect parks and, therefore, they become neglected and dangerous. Rezoning them for development seems to be the logical way forward, but this is unacceptable. This pressure will escalate as urbanisation increases in Africa. It is predicted that more than 60 per cent of the global area projected to be urban by 2030 has yet to be built; this will have huge effects on urban nature and human health and well-being.
Urban ecological studies at the NWU started in our home city and expanded into other areas of the province. The greater Potchefstroom area is one of the most intensively studied urban areas in the country. It is well known as a case study among urban ecologists worldwide due to numerous international research papers and conference presentations. These studies have shown the importance of the conservation of fragmented urban grasslands and wetlands. They have high native biodiversity and are still highly functional and provide important ecosystem services. It has also emerged that grassland degradation and loss of native bio-diversity and the increase in invasive plant species need to be addressed urgently.
Gardens form a large part of the “urban green” and provide important ecosystem services. In 2008, a study on 100 home gardens in the (then) Tlokwe municipality found 880 plant species, an unexpected 255 species of which were indigenous, including 18 species on SA’s red data list. Gardens can be a refuge for endangered species, but also a source of plant invasions. A total of 88 declared invader species were also found in these gardens. This study is currently being replicated and includes social aspects in terms of residents’ plant choices for their gardens. There are several other studies. Health clinic gardens in the entire NW province were investigated for their value and importance in addressing food secur-ity and other ecosystem services. In collaboration with plant eco- physiologists and soil scientists, the condition of the historic oak avenue is being studied.
How urban ecology can be implemented in planning through green infrastructure planning is the central theme of projects cooperating with urban planners. As the importance of soil organisms in urban areas has not been well researched, we participated in an international comparative study with soil scientists and microbiologists in four countries. This, to determine diversity and soil decomposition rates of soil organisms. The project is known as the rooibos tea bag experiment. Urban ecologists mainly work for (larger) local governments and private ecological consultation firms.
For more information on urban ecology, contact Prof. Sarel Cilliers (Sarel.Cilliers@nwu.a.c.za) 082 524 0383 or Dr Marié du Toit (13062638@nwu.ac.za).