When thinking about what we need to do to address the global biodiversity crisis, chances are the urban landscape is not the first thing that comes to mind. The best way to slowdown species loss is to protect natural areas. In fact, all the bold, ambitious plans to address biodiversity loss propose setting aside and managing large tracts of natural land where species can continue to thrive. The eminent biologist, E.O. Wilson, has called for setting aside 50% of the earth’s land area for nature, and National Geographic’s Campaign for Nature is aiming for 30%.
Developed urban areas, by their very nature, are destructive of the natural systems that they replace. Nature, when it exists in urban areas, is an amenity, planned and designed to fulfill an array of social, cultural, and aesthetic or spiritual values. Historically, preserving or enhancing biodiversity for its own sake has not held a prominent place among those values. However, that might be changing as more people become concerned about species loss and begin to recognize the potential for urban areas to support biodiversity. Urban areas occupy a small fraction of the earth’s surface, but there are many densely populated places in Europe, China, and even Florida, where urban areas occupy a significant portion of the landscape. Some projections for Florida estimate that up to 30% of the state could be in some form of urban or suburban development within the next few decades. This means how we design and manage our landscapes and outdoor environments will have a major impact on the state’s biodiversity.
Nature in cities exists both as private spaces associated with dwellings, or public green space, such as parks, roadways, or natural areas set aside or left undeveloped for various reasons, such as being too wet or inaccessible. This variety of green spaces creates a patchwork of opportunity for supporting biodiversity in the built environment. The young field of urban ecology has generated many studies that have increased our understanding of how this patchwork of varying green spaces affects biodiversity in cities. Thanks to those studies, our understanding of the distribution and abundance of various species or groups, such as plants, birds, and insects both within cities and across urban-to-suburban and urban-to-rural gradients, has increased significantly. At the same time, there has been a surge of interest in using more native plant material in landscape designs and planning. Florida has a very strong native plant society, with active local chapters throughout the state, and has an expanding network of nurseries producing native plant material on a large scale. Many prominent landscape architecture firms and projects throughout the state are emphasizing greater use of native plant species in their designs.
This increased use of native plants in landscape design has knock-on effects for native animals. The research of Doug Tallamy, an entomologist from the University of Delaware, and others has shown that native plants support a greater abundance of native insects due to the close associations they have developed over evolutionary time. This greater abundance of insects, in turn, provides more food for higher levels of the food chain, such as birds, lizards, and other vertebrate and invertebrate predators. Native plants are essential to enhancing biodiversity in urban landscapes, but using biodiversity as an organizing principle for outdoor development goes beyond the use of native plants. Several studies have shown that plant diversity in some cities actually exceeds that of the surrounding native areas due to the introduction of horticultural varieties from other parts of the world. Introduced horticultural varieties not only broaden the aesthetic palette of landscape design but can provide crucial resources to birds, pollinators, and other urban biotas, augmenting, or even exceeding, what native plants can provide.
Designing with biodiversity in mind means thinking carefully about habitat structure, such as nesting habitat and food resources for songbirds, floral resources for pollinators, and the balancing of different plant families to provide broad-based support for diverse insects and animal life. It also means designing and constructing spaces that will not require heavy use of herbicides, insecticides, fungicides, and other harmful chemicals. Monoculture turf with its heavy reliance on chemical inputs is often upheld as the classic example of a landscape hostile to biodiversity. Weedy public roadsides and medians can support a hundred times the amount of thriving insect life, including bees, butterflies, and other pollinators, than the carefully managed, high-input manicured medians characteristic of homeowners associations and other private developments. Embracing more diverse turf would require a major change of social within the HOA-dominated landscapes of Florida, but there is great potential for creating more biodiverse turf-scapes. The imperative for embracing biodiversity as an organizing principle is especially relevant in Florida which represents one of the world’s biodiversity hotspots. The region hosts a tremendous number of endemic species, but it has lost much of its original habitat and is losing more to development. Yes, we need to protect, restore, and properly manage our remaining tracts of natural lands where we can; however, we can support a richer and varied life within developed areas and helping more species thrive there if we let biodiversity be a greater guide for outdoor development.
by Dr. Patrick Bohlen
Dr. Patrick Bohlen is Director of Landscape and Natural Resources (LNR) and Arboretum, and Professor of Biology at the University of Central Florida. He received his PhD in entomology from Ohio State University in 1994 where he studied soil and ecosystem ecology. He was a research biologist at Archbold Biological Station in Lake Placid, Florida for 11 years prior to coming to UCF in 2010. The LNR department is responsible for landscape operations and natural resource management on UCF’s main campus, Lake Nona medical campus, and other UCF facilities. Other responsibilities include: landscape design and master planning, landscape installation and maintenance; landscape irrigation; management of natural areas and conservation easements; and storm water infrastructure. Dr. Bohlen also oversees the UCF Arboretum, which together with LNR, provides opportunities for relevant, experience-based learning, urban ecology research, and human connection with ecosystems and landscapes.