Sustainable Management of Urban Green Environments: Challenges and Opportunities
Samuel Kiboi, Kazue Fujiwara, and Patrick Mutiso
Abstract Urban green areas not only provide aesthetic qualities but also provide important ecosystem services in ever-shrinking habitats, and therefore need sustainable management practices. The western and northwestern parts of Nairobi are within an upland dry forest that stretched from Karura to Ngong forests with a characteristic vegetation composition. Much of that vegetation has been replaced by exotic species and, over time, the original indigenous tree species composition may be lost. No previous studies have profiled the local vegetation structure in Kenya and then used this knowledge to restore the urban green environment. We carried out studies in Karura and Ngong forests and used 16 carefully selected species to recreate a natural forest using the 'Miyawaki method' at the College of Biological and Physical Sciences of the University of Nairobi. In just 16 months the species have established extremely well, with the best performing species (Ehretia cymosa) growing to more than 210 cm from just about 43 cm. We expect to recreate a quasinatural forest and use such studies and methods to restore urban green environments in Kenya.
Keywords Natural green environment restoration • Upland dry forests • Urban forest ecosystem services • Urban vegetation • Vegetation structure of Nairobi
Urban green environments in developing countries especially are under constant pressures resulting from rapid urbanization, which can be sometimes unplanned. The greatest challenge today is to manage the environment in a sustainable way whilst offering pleasant surroundings for the urban dweller, and at the same time maintaining some natural areas. Nairobi, for example, has been ranked among the top ten cities in the world that have the biggest declines in liveability over 5 years with a score of −2.9 % according to the latest Global Liveability Survey of 140 cities worldwide (Economist Intelligence Unit 2013). The unit measured cost of living, health care, pollution, education, infrastructure, and green spaces to obtain the scores. In general, green environments, and specifically trees, offer an array of benefits that can be categorized broadly into: ecological benefits, architectural functions, climate moderation, and monetary benefits, as well as recreational and social values (TEEB 2011; Bolund and Hunhammar 1999).
Challenges in Achieving Sustainable Green Urban Environments
The challenges to sustainable green environments in urban areas are many and require a proactive approach and the cooperation of all citizenry. Apart from an effective regulatory system, an informed citizenry will keep the environment in better condition than those who have to be policed to adhere to standards. Some of the problems facing urban areas in Kenya are severe and common to many cities in the developing world, although they may vary in magnitude. Management of urban environments in the developed world is more effective, and hence the environments are cleaner and greener but may have experienced pollution challenges in the past, e.g., Yokohama in Japan had major pollution problems in the 1960s. Some of the major environmental challenges facing urban environments in Kenya are: