Strategies for Increasing Biodiversity Conservation in Cities Using Wastelands: Review and Case Study

Abstract

Urban wastelands have great potential for promoting biodiversity. As many cities shrink in size, these unused areas will continue to increase while available revenues for land maintenance will decrease. Managing such wastelands in ways that promote biodiversity, such as encouraging spontaneous vegetation and ecological succession, reduces maintenance costs while also providing many environmental and social benefits to the urban population. I reviewed the literature since March 2014 and found 31 studies of factors that influence biodiversity in urban wastelands. There is a strong geographic bias toward studies in North America (15) and Europe (10), and a taxonomic bias toward arthropods (16), plants (11), and birds (6). These studies often show that wastelands contain as much, and often more, biodiversity than other urban green spaces. Consistent with a previous review, local factors (area, age, soil, microclimate, and previous and current land use) are dominant influences on biodiversity in wastelands, with landscape factors often playing a secondary role. Next, I discuss how these factors have played a role in the Knoxville Urban Wilderness (KUW) project which has been very successful in acquiring and managing a variety of wasteland parcels to achieve economic and ecological goals. Examples of their application include increasing land acquisition (more area and spatial habitat diversity including soils and microclimates), increasing connectivity (greenways and trails), and maintaining the parcels in different stages of ecological succession. These efforts have undoubtedly contributed significantly to the biodiversity of this urban region. For example, although the KUW occupies a tiny fraction (688 ha) of Knox County, roughly two-thirds of Knox County bird species utilize the KUW, and about 13% of known threatened species in Knox County have been recorded in the KUW. I also briefly discuss how the KUW has successfully coordinated the acquisition and management of many parcels of vacant land, worked with many stakeholder groups, greatly increased public exposure to biodiversity, and contributed over $8 million to the local economy each year.