Scientists have taken a new interest in how plant and animal life respond to the city.
Urbanization brings with it all sorts of effects on human behavior, but sometimes lost in the mix are the corresponding effects on plant and animal life. Understanding this ecological impact will become increasingly important as cities expand their environmental footprint and implement policies to address climate change. To date, however, the field of "urban ecology" has remained relatively quiet.
Earlier this year a trio of ecologists analyzed where other ecologists conducted their research and discovered that, by and large, it wasn't in cities. The group categorized some 2,500 studies published in ten influential ecology journals between 2004 and 2009 and found that only 4 percent targeted "densely settled" areas. Looking more closely at studies of dense settlements, the researchers realized that many actually examined protected areas within a city — not really the city itself:
Despite the indication of the geospatial analysis that many sites were located in urban areas, content analysis revealed that many of these were protected fragments situated in densely settled zones — in other words, many of these studies were not conducted for the explicit purpose of understanding the ecology of densely settled places.
Fortunately, this inattention to cities seems to be changing, reports Courtney Humphries in a recent news feature on the "growing field of urban ecology" in the journal Nature. Humphries traces the surge to a series of "urban long-term research" grants co-sponsored by the National Science Foundation and the U.S. Forest Service. The official aim of these ULTRA grants, as they're known, is to understand the "dynamic interactions between people and natural ecosystems in urban settings."
Humphries writes that 21 ULTRA awards have been issued to various research teams, at a total of roughly $6 million. A group of U.C.L.A. researchers is studying the impact of tree-planting programs in major U.S. cities. Ohio State scholars have studied whether vacant city lots are suitable for conversion into food gardens, and how various pest-killing insects respond to such transformations. Boston-area scientists are modeling the flow of carbon dioxide throughout a city and observing how certain plant species respond.
Other work in the field is gaining attention as well. Earlier this week the New York Times highlighted a recently published study comparing the growth of red oak trees in the city to those in the Catskills. The researchers found a number of key differences: city trees had eight times as much biomass than those in the country, grew leaves with greater area, and contained higher concentrations of leaf nitrogen.
The new focus certainly isn't limited to American cities. New research out of Australia, publicized on the news site Phys.org, looked at how various types of urban development impacted birds in Brisbane. While all types of urban growth reduced bird populations, the researchers found that sprawl accelerated this decline compared to areas with higher residential density — particularly when green spaces were maintained. Who knew birds were urbanists too?