Why Bother With Urban Biodiversity?

March 6, 2015

By Dean Pentcheff On one day in the past decade, someone who never lived an urban life came to a city. Perhaps it was a man in China looking for work in Beijing, a hungry woman from a rural farming family in India moving to Hyderabad, or perhaps a baby born in a Los Angeles hospital. That unheralded, unnoticed arrival delineated a turning point in human history. That person was the one who tipped the scale from rural to urban. For the first time, more than half of us live in cities.

Urban vs. rural population trends (United Nations. 2014. World Urbanization Prospects. ST/ESA/SER.A/352)

Urban vs. rural population trends (United Nations. 2014. World Urbanization Prospects. ST/ESA/SER.A/352)[/caption]That trend is expected to continue, as world population expands and farming necessarily becomes ever more efficient. So what used to be a specialized and peculiar surrounding for people — cities — is now the new normal. It turns out that this matters a lot. The living world around us provides the “ecosystem services” that keep us alive. We are used to the idea that cities and towns provide us services like clean water, electricity, and fire protection, and we pay to keep those coming. In a way that we have only started to understand, though, there are many services that the living world provides us “for free” (and those quotes are deliberate): clean air, oxygen itself, the water supply, waste decomposition, pest and disease control. While we may not be writing checks for these services, it is clear that we still need to invest in keeping them running. Ecosystem services are provided by the physical and biological community around us. Those communities are built on biodiversity — the sum total of biological diversity, from the ecosystem level right through genetic variability within species. That is a direct reason why the biodiversity in and around cities matters: it is the portion of the living world that is closest to most of us and is therefore best placed to provide the services we need. There are less-specific but still important reasons why biodiversity matters, too. The biodiversity around us frames our perception of our surroundings. Trees and plants define landscapes, animals (large and small) populate the visual and sonic world in which we live, even in the face of urbanization. There is growing evidence that human health and wellbeing is directly linked to the presence of features like biodiversity and urban river parkways. But there is a problem. Traditionally, perhaps because we are used to thinking that most people live rural lives, we have a tendency to think that real biodiversity exists only outside cities. Aren't cities, by their very nature, the displacement and destruction of biodiversity? Who thinks of looking inside cities to discover and describe biodiversity? That dismissive attitude towards urban biodiversity has been, to our embarrassment, widespread even among biologists — and we should have known better. Scientists have not been immune to the message we see on TV all the time: interesting, diverse, and cool organisms exist only in remote “pristine” environments. It seemed more valuable to study “undisturbed” nature. Only in the last decade or so have we begun to see the significant growth of biodiversity and ecology investigations focused on urban systems. Now, in contrast, we are perceiving the importance of understanding the living world right where most people live. That has launched a new wave of investigations, including NHMLA's very own BioSCAN project. To our surprise (as old-fashioned biologists), the moment we started looking in cities, we started finding extraordinary unsuspected biodiversity. Of course, the bulk of that diversity is in the smaller creatures, notably insects. In retrospect, this shouldn't have been a surprise at all. Though cities differ from what was there before, cities are incredibly heterogeneous habitats. There are buildings with habitable surfaces and nooks, vegetation that, thanks to happy gardeners, is likely more diverse than the pre-existing flora, cracks in sidewalks, patches of soil, and all the other variously constructed or deconstructed spaces that make a city. All of those locations can be home to a diverse set of small creatures. The BioSCAN project has already discovered dozens of new species previously unknown to science (as well as recording the occurrence of many species only previously known from elsewhere). What we understand very poorly right now, though, is how the actual physical nature of an urban space drives the resident biodiversity. What matters? Temperature? Moisture? Closest plant species? What doesn't matter? Those are the kinds of questions that we hope to answer with the BioSCAN project's biological, physical, and landscape sampling across space and through time.

City Flower

Without answers to those questions, it is impossible to productively plan urban development with biodiversity in mind. Urban planners are making decisions every day, whether they have deep knowledge of the consequences or not. If we want our future lives to be in healthy, diverse cities, we need to understand how to develop for biodiversity today. Contributing to that understanding is BioSCAN's ultimate goal.

(Posted by: Emily Hartop)

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