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Fringe Conservation: a Call to Action

2002; Wiley; Volume: 16; Issue: 5 Linguagem: Inglês

10.1046/j.1523-1739.2002.16501.x

1523-1739

John M. Marzluff,

Ecology and Vegetation Dynamics Studies

As I drove from the urban jungle of Seattle to the crest of the Washington Cascade Mountains to start the new year, I was both reminded of how far we have come in conserving our natural resources and shaken at the thought of how much remains to be done before we effectively preserve a reasonable portion of them. As I drove higher in elevation, I entered state and national forest lands, green and then white as rain turned to snow. The high-elevation forest is worked lightly now thanks in part to the Northern Spotted Owl. Forests are maturing, and logging of surrounding private lands keeps a mix of forest ages on the landscape. Most species that live in and comprise these forests are viable; the long-term prognosis is that a diversity of forest ages will be maintained by owners and managers. This is the good news. The bad news comes as I begin my return trip, battling traffic through one the "best" examples of urban sprawl in the United States. In western Washington, as elsewhere, much of our most productive lowland forests have been converted to suburbs. Globally, about 6% of Earth is covered by impervious, anthropogenic surface, but most urban areas are surrounded by lower-density "sprawl" that affects a much larger area. The amount of productive land needed to sustain urban areas is one or two orders of magnitude greater than the city's actual area. The global significance of sprawling human settlement is best appreciated by looking at satellite images of Earth at night. Most of Europe, eastern North America, Asia, and the temperate and tropical coasts are densely settled. This has occurred in just the last few centuries: in 1700 there were 14 cites with>200,000 people, and now there are 171. Although dramatic, this urbanization of our planet has been largely ignored by conservation biologists. We often live in urbanizing areas, so we do little to understand this effect on biodiversity or provide the science that planners and policymakers need to guide sustainable settlement. Rather, we travel from suburbia to exotic places that hold few humans to study state, national, and resource-production lands. Often we tell distant, poor inhabitants how to preserve their biotic heritage. While we have preached the gospel far from home, our growing economy has fueled unprecedented land conversion that has resulted in the endangerment of thousands of species. Endangerment from urbanization rivals or exceeds endangerment from resource extraction or agriculture. If we are to conserve the magnificent diversity of life that characterizes our productive inland and coastal lowlands, we must look closer to home. Action is needed to restore degraded areas and conserve remaining natural areas in and around our backyards. Effective conservation of this fringe between settled and wild lands is an enormous challenge: economics favor development, much of the natural landscape has been altered, invasive species are common, policies affecting land use are myriad and come from many jurisdictions, and land ownership is diverse and fragmented. Unfortunately, our understanding of these complexities is rudimentary. Advice from conservation scientists to urban planners has been simplistic: preserve large areas of native habitat, minimize edge, link fragments with corridors, and maintain keystone species. Such advice may be good in vast, natural landscapes, but in urbanizing areas it often fails to affect land-use policy in a way that has beneficial consequences on the ground. The economic value of land is inversely related to its abundance, making the costs of preserving or connecting the last fragments prohibitive. Among the aims of urban growth management is the preservation of open space, but open space is not being preserved in all urban areas, and where it is, reserved space is rarely adequate to maximize protection of biodiversity. Rather, it represents a compromised blend of critical upland habitats, water-supply buffers, and lands unsuitable for development. Human desires often trump other species' needs, so little land remains far from the bulldozer's blade. The small fragments of natural habitat that are purchased and connected often become ecological sinks and traps in the face of abundant invasive species and human trampling. Our challenge as conservation biologists is to recognize the ecological importance of practicing our craft in our backyards, neighborhoods, and cities. It is easy to give up on these areas, label them as ecological wastelands, and focus on conserving areas far from settlement. I contend that this is not a viable strategy because settlement will march ever closer to now-distant lands. This is likely in developing as well as in developed countries, for within 50 years most humans are projected to live in cities. In fact, in a perverse way, conservation regulations that reduce the use of distant lands for resource production may actually speed urban sprawl. In western Washington, for example, small forest landowners often subdivide or sell their land to developers because they cannot harvest enough timber to make a profit. ( Washington's Department of Natural Resources has estimated that 165,000 acres [66,775 ha] were converted from small private forests to urban development from 1979 to 1989.) Regardless of the speed of sprawl, an important way to keep distant lands "distant" is to guide the march of settlement so that it reduces impacts on wildlands it eventually will abut. To effectively guide settlement, we need to increase our interdisciplinarity. Not only do we need to develop a rigorous understanding of how settlement affects the richness and relative abundance of species, we also need to understand what motivates people to develop and settle land the way we do; how land-use policy is crafted, implemented, and informed by economic and ecological reality; and how planners, managers, developers, and architects respond to human desire and policy to create settlements. We must also pick our environmental battles carefully along the urbanizing fringe. We cannot save everything or stop all development. We can, however, affect the pattern of settlement by determining what arrangements of built and unbuilt land least affect native organisms, direct development to occur in common habitats rather than rare ones in need of preservation, suggest how to develop and restore lands around reserves to reduce loss of ecological functionality within them, identify especially invasive exotic species and devise regulatory and physical barriers to contain them in settlements, and lobby for increasing the global sustainability of what is built. We need to consider, research, and advise planners on how to arrange natural and built lands at the scale of the subdivision. Subdivisions near wildlands need special attention so they function to reduce, not accentuate, the effects of settlement on protected core areas. If we also consider subdivisions from a wider, regional perspective, we may be able to conserve lands with less current economic value and more ecologic value just beyond the developing fringe (e.g., guide purchase by conservation trusts or use mitigation banking). This challenge is being met with increasing enthusiasm. There is a resurgence in the study of ecological processes in urbanizing environments, and the knowledge gained is being applied to conservation. Long-term studies of urbanization at large geographic scales are also underway in several U.S. cities, including Baltimore, Phoenix, Seattle, and Chicago. This work has a good chance of changing settlement policies, because researchers and academicians from many disciplines are forging relationships with planners, managers, and policymakers. Changes in graduate education—more interdisciplinary study, more connection to local issues and policies, more focus on teamwork—will be required to train future generations of urban conservation ecologists. At institutions in the United States (Arizona State University, University of Southern California, University of Washington) and Germany ( Humboldt University, Free University of Berlin) national funding for this is now being provided. Rising to this challenge is effective, stimulating, and scientifically rewarding. Green spaces in and around places such as Boulder, Seattle, Chicago, and Phoenix are increasingly being viewed as valuable for conserving some native plants and animals, educating humans about and enriching them with nature, and slowing the spread of invasive species into wildlands. Interdisciplinary urban ecology projects are addressing two long-standing criticisms of our field: an inability to forge conciliatory relationships between social and natural sciences and use of ecological experiments on inappropriately small scales. Much remains to be done, which is why I call you to action. Think of settlement on Earth and imagine the prospect for native lands if the rate of sprawl continues at anything like its present rate. Projections are for urban populations to increase by 10–30% over the next 25 years. Much smaller increases in the past have doubled the area of converted land around cities. Now consider how your teaching, research, management, and planning energies can be used to better understand and reduce the effects of sprawl on biodiversity. In my experience, students in your conservation biology and ecology classes will welcome lectures on the drivers and consequences of urbanization. They will be amazed and attentive if you take them just outside the classroom so they can see and measure the effects of land conversion. If you can go to areas likely to be developed, then their work can be assembled into before-after-control studies that vividly show the changes that occur when we settle natural areas. Encourage them to map what they see so you can track changes through time. In this way you can expand your research to address issues of local importance that will engage your students and that will be appreciated by local conservation organizations and policy-makers alike. Get involved in local land-use planning and bring to the process your scientific experience. I think you will be challenged to apply the generalities of conservation biology to real-world decision-making; these challenges will increase the relevance and precision of our science. To effectively guide settlement, you must get out of your comfort zone and interact with those in other disciplines so you can learn how to make conservation of biodiversity in settled areas appealing to people and part of the policy process. Talk to your neighbors so they understand how lawns, pets, and purchases affect natural species in your neighborhood. Engage them to work with you to restore and maintain native elements of our surroundings. Instill in them a new land ethic that values native vegetation for its own sake not for its development or recreation potential. Keep the global vision in your conservation biology, but root it strongly in and around the places you live.