Urban Ecology

neimela

Rating: ★★★★½

Niemela J, Breuste JH, Elmqvist T, Gunterspergen G, James P and NE Macintyre. (eds). 2012. Urban Ecology: patterns, processes and applications. Oxford University Press. ISBN 978 0 19 964395 0.

It’s always interesting to see how perspectives change in any field and ecology is no exception. Twenty years ago, the words ‘urban’ and ‘nature’ would only be seen together if they were in opposition. No-one would suggest the towns and cities could create environments or modify habitats. It’s not that there was a denial of wildlife in settlements, it’s just that it was only really seen as an opportunity for school-aged children to do some “nature study” and get a background in ecology before seeing “real” nature! That view is changing rapidly. The first texts looking at cities tended to take and environmental approach e.g. urban heat islands, climate patterns etc. This was followed rapidly with works on urban nature and conservation from wildlife in parks to maintaining sparrow numbers in backyards (although that has now become an issue in its own right!).  The next stage was to look at urban areas as discrete ecosystems with some suggesting buildings were similar to cliffs. This brings us to the mid-late 1990s. The last 10 years has seen a solid move towards a new sub-discipline of urban ecology and now, with this text, we can see another shift towards ecology as a planning tool in sustainable urban development.

As if to underline the ideas above, this text opens with an excellent, brief overview urban ecology’s development. It shows both the growth of the subject and its arrival as a sub-discipline (as opposed to a more restricted study by a few).  From here, the book is divided into 5 sections. The first deals with the abiotic environment, largely the human-modified side. The obvious, and oldest, case is urban climate with notions of the heat island effect (although this is not without its critics).  However, it is now recognised that urban soils have their own distinctive characteristics and that urban pedogenesis creates more complex situations than seen in wild areas. To this is added hydrology but with a twist not so much of chemistry (which it would be nice to see considered further) but of physical barriers such as urban surfaces and infiltration rates. There is also discussion of land use and the ways in which this can be seen as a proxy for wildlife as well as a series of habitats. One is used to seeing land use considered as part of geography but using it, as they do here, as an ecological indicator is a very interesting move. Leaving aside its ecological value, the sheer ubiquity of the concept helps draw more people into the subject (and since this is a review rather than a definitive work, one must assume an audience skewed in this direction).

Section 2 looks at ecology and urban biodiversity, focussing on urban patterns. This section is full of small chapters offering tantalising glimpses of the potential of urban areas to promote biodiversity. Wetlands are under threat globally but some in urban areas manage to survive. These are crucial areas, studied here not just for their biodiversity but also for the impact of changes brought about be people.  Gardens used to be considered useful green areas or even small nature reserves but their collective size, relative to overall land use, means that they are now part of a larger tapestry whose design influences urban biodiversity. Pavements and walls offer more habitats. The vegetation of walls (and graveyards) has been a popular study for decades but now we add pavements and gullies to the mix illustrating now diverse the habitats really are. The two final contributions look at vegetation diversity and the impacts both positive and negative of humans on urban ecology.
This section is followed by a complementary one examining the processes which affect the patterns noted above. We start with a different take on the topic with the argument that human and non-human organisms are co-evolutionary with respect to urban areas: each affects the other. Given common tales of the urban fox, this is not surprising.

Section 3, related to this, focusses on the processes that give rise to these patterns. It’s here that the shifts in ecological study are most clearly seen. Ideas of urban areas as barren landscapes have been replaced by consideration of interactions; cities take away but they also give. This relationship could now reasonably be considered coevolution. It’s seen in the way that bird species vary in number (one of the best cases is the house sparrow). Another case, noted here, is urban vegetation. Gardens have been seen as wildlife refuges for certain species for some time but now other urban spaces are being included in the study. As with animals, the impact of the city is mixed altering not only the composition of the area but also the abundance. Consideration then turns to arthropods who presence in settlements has probably outlasted other organisms. Urban areas make great habitats for arthropods where the refuse heap allowed expansion of selected species, often to pest proportions e.g. flies. Whilst most of these studies follow a similar path, work on  amphibians takes a different tack and one that widens the usual scope of study. Here the author defines three states: urbanophiles, urbanophobes and urbanoblivious. Loosely, this refers to those amphibian species who tolerate human environments, those who don’t and those who are largely hidden from human sight and therefore engender to response. It’s an interesting choice of ideas but it does allow us to examine our responses more carefully. Is this part of the urban ecology or just our response to the presence of species? A final chapter attempts to tie this together in a study of metacommunities.

The final two sections turn towards the social and planning aspects of urban ecology. As such, it’s where the ecology meets people. It’s about looking at the ecological costs and benefits of cities (because, as is made clear, there is no simple black and white answer). It’s also about taking this knowledge and using it to better plan our urban environments. The first set of chapters focusses on ecosystem services. The big question is whether cities are net costs or benefits to the natural environment. Despite some useful discussion, the conclusion is far from clear. For example, urbanisation is widespread so it would be difficult to find an area completely free of impact. Further, impacts change through time with environmental impacts low for new or developed cities but high in the middle when the place is expanding and wealth is limited. It might be possible to look at past settlements and there is value in that, but it is only one part of the story that needs to be considered (we get the example of wetlands in urban areas to highlight this. A final chapter considers that there is much to be gained from careful integrated planning but this has yet to be seen in any large-scale effective way.

Cities are key issues and there has recently been a number of committees called upon to examine pressing environmental issues. One common factor is urbanisation. An excellent opening chapter highlights the broad scope of ecology in cities coming to the conclusion that cities and ecology are inextricably linked and should be planned in concert. We are told that cities considering wildlife and open spaces have a better social health than those that don’t. Further, by moving from physical planning to environmental planning we can reduce negative effects of city plans, moving towards the goal of sustainable development. We need to find the mechanisms to do so, including the more familiar financial target.  A final chapter highlights the way in which urban ecology has developed and where it could go.

This is an excellent text that can be used at so many levels. As an review of current understanding in urban ecology it is outstanding. As a guide to inform environmental education it gives numerous examples. The strength of this book lies in two key design aspects – the large number of contributions and the focussed brevity of each chapter. This allows the reader to explore the very wide interests of urban ecologists but also gain a good grounding in the main concepts. Chapters are noted for their openness in discussing the limitations and issues and well as the positives of each of the main topics. It helps that the quality of writing is uniformly excellent making it a pleasure to read. This must be seen as one of the best recent books on urban ecology; it deserves the widest readership.

 

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