Urban areas cover only approximately 3% of the total area of the earth’s land surface but urban growth is regarded as a major threat to biodiversity (Kowarik, 2011). 50% of the worlds population lives in urban areas and is increasing at an average annual rate of 1.9% (UN,2011). The importance of biodiversity in cities is seen by many to be not only a conservation issue but also a human health issue. Urban Ecology has a long history mainly in Europe. The succession of vegetation in bombed ruins of the Second World War was studied in many cities and in the 1970s ecological studies in cities started with investigations on energy flow and nutrient recycling. Urban ecology is now seen as a way to develop more sustainable cities and a mechanism to investigate how living organisms relate to their environment in cities (Sukopp, 2002). This week’s discussion questioned the ecological role of increasing native biodiversity in urban areas. Are there benefits in trying to understand or enhance the ecological processes that may be occurring though increased native biodiversity? Kowarik (2011) states that conserving and enhancing urban biodiversity benefits human wellbeing and public health. Biodiversity also provides opportunities for people to interact with nature more often and therefore fosters a wider interest in nature conservation issues (Goddard et al. 2010). Has the social science behind these observations been studied and quantified? There is definitely a feel good factor in being part of restoring natural diversity to a city as seen by the number of groups involved in restoration in Christchurch and surrounding areas. But does this foster a greater interest in protecting our truly wild areas? A concern raised was that money could be diverted from conservation issues to fund biodiversity enhancement in urban areas giving little benefit to ecosystem functions.
What kinds of ecosystem functions can we create or restore in cities?
Cities as a whole are human-generated (Hobbs et al. 2006) novel systems, where species are thrown together in communities of compositions not found in nature. Urban ecology has shown cities to have both negative and positive impacts on biodiversity. Much of the plant diversity within a city is of an exotic nature causing cities to be hotbeds for exotic garden escapees, which can become pests in natural landscapes. On the other side of the coin can urban areas be seed sources and/or refuges for rare or endangered native species?
What is the scientific (and other) value of doing Urban Ecology? To answer this question I feel more research is needed on urban biodiversity and its related ecological and social implications.
References cited
Goddard, M. A., A. J. Dougill, and T. G. Benton. 2010. Scaling up from gardens: biodiversity conservation in urban environments. Trends in Ecology and Evolution 25:90-98.
Hobbs, R., S. Arico, J. Aronson, J. S. Baron, P. Bridgewater, V. A. Cramer, P. R. Epstein, J. J. Ewel, C. A. Klink, A. E. Lugo, D. Norton, D. Ojima, D. M. Richardson, E. W. Sanderson, F. Valladares, M. Vila, R. Zamora, and M. Zobel. 2006. Novel ecosystems: theoretical and management aspects of the new ecological world order. Global Ecology and Biogeography 15:1-7.
Kowarik, I. 2011. Noval urban ecosystems, biodiversity, and conservation. Environmental Pollution 159:1974-1983.
UN, 2011. Urban Population and Development 2011. UN, New York United Nations Department of Economic and Social Affairs. Population Division.
Urban Ecology is a completely new science for me. In South America the main concern is the conservation of natural habitats, specially the Amazon, as well as their species and ecological functions which are still being under study. There is not doubt that urban growth affects biodiversity directly and indirectly, so Urban Ecology as a science may be helpful in developing measures to decrease negative impact and make current and future cities more environmentally friendly.
ReplyDeleteI think that there are a range of reasons why even fundamental ecologists should invest time into doing Urban Ecology. Urban systems provide usually easy-to-get-to opportunities for restoration experiments that we can use to look at community assembly processes such as priority effects. As you point out, cities are hotspots of alien plant diversity, which, as 'natural experiments' provide us with ample opportunities for fundamental research on plant community structure, plant-herbivore interactions, above and below-ground processes, etc. Cities create clear gradients in abiotic conditions and disturbance regimes that we can use to investigate behavioural ecology questions, (meta-)population processes and community patterns and processes.
ReplyDeleteAnother way to look at urban ecology is to think of cities as colonies. I have spent a lot of time on seabird islands where there are colonies of procellariiformes that range from hundreds to tens of thousands of individuals. Usually seabirds burrow to provide a secure nestsite for their egg. The impact that all of this burrowing (and the guano brought back from ocean foraging) has a tremendous impact on the local habitat with forest being undermined and many plant species not being able to compete at all. These are fascinating ecosystems and are eagerly studied. You can probably think of your own habitat that is highly structured by one species or species group (e.g. grasslands, beech forests, termite colonies). Urban ecosystems are somewhat similar in their level of impact and create novel conditions for species to flourish or fail in. There is certainly value in looking at ecological processes in this setting.
ReplyDeleteThe fact that urban areas are increasing worries me due to the consequenses for human health. In that frame urban ecology seems promising in the idea of developing more sustainable cities. Though the priority of city sizes compared to rural areas must be considered. If we make the urban areas bigger due to incorporation of "green areas", thus the rural areas become smaller. So larger urban areas, smaller rural areas or perhaps just smaller difference between those two types of areas. Is that desirable? Personally I believe it depends very much of the existing difference between the areas. Since I'm from Europe where nearly all land is or have been agricultured, I argue to keep the difference as great as possible. Let the rural areas be rural! The urban areas will increase anyway due to population ect. Saying that I still consider urban ecology to be important in the sense of contributing to the future construction in cities.
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