Environmental scientists warn about the consequences of unchecked land use
BY TERRY DEVITT AND MARK SHWARTZ
Divided slope farming, above, is used to reduce erosion rates in Washington State’s Palouse region. Sustainable land-use practices are essential if we are to balance human needs, the continued flow of ecosystem services and the long-term health of people and the planet, according to a study in Science.
The massive conversion of the world's natural landscapes to agriculture and other human uses may soon undermine the capacity of the planet's ecosystems to sustain a burgeoning human population, according to a new report in the journal Science.
"Land use has generally been considered a local environmental issue, but it is becoming a force of global importance," writes Center for Conservation Biology researcher Gretchen C. Daily, co-author of the Science article. "We face the challenge of managing trade-offs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term."
An associate professor (research) of biological sciences and senior fellow at the Stanford Institute for International Studies, Daily is among 19 co-authors of the paper "Global Consequences of Land Use," published in the July 22 edition of Science.
In their report, the authors conducted a global review of scientific research on major land use practices?agriculture, urban and rural development, deforestation and other natural resource extraction?and their impacts on the environment, including changes in atmospheric composition, land cover, the hydrologic cycle and biological diversity.
"Human activities now appropriate nearly one-third to one-half of global ecosystem production, and as development and population pressures continue to mount, so could the pressures on the biosphere. As a result, the scientific community is increasingly concerned about the condition of global ecosystems and 'ecosystem services,'" the authors write.
Global threatAccording to the authors, the escalating transformation of the world's forests, wetlands, savannahs, waterways and other native landscapes is the biggest potential threat to human health and global sustainability.
"Short of a collision with an asteroid, land use by humans is the most significant impact on the world's biosphere," says Jonathan A. Foley, a University of Wisconsin-Madison climatologist and lead author of the paper. "It may be the single most pressing environmental issue of our day."
According to Foley, many agricultural practices built on Western-style methods are unsustainable, requiring large applications of chemical fertilizers and further sculpting of the landscape to divert water to marginal lands.
"While land use practices vary greatly across the world, their ultimate outcome is generally the same: the acquisition of natural resources for immediate human needs, often at the expense of degrading environmental conditions," the authors write.
"What strategies can ameliorate the detrimental effects of land use?" they ask. Examples include making agricultural production more efficient; increasing green space in urban areas; employing agro-forestry practices that provide food and fiber yet maintain habitats for threatened species; and maintaining local biodiversity and associated ecosystem services, such as pollination and pest control.
"Many of these strategies involve management of landscape structure through the strategic placement of managed and natural ecosystems, so the services of natural ecosystems (e.g., pest control by natural predators, pollination by wild bees, reduced erosion with hedgerows or filtration of runoff by buffer strips) are available across the landscape mosaic," the authors note.
Success storiesThe report highlights several ongoing examples of sustainable land use practices that have provided economic and environmental advantages:
Implementing regional land-use strategies that recognize both short- and long-term needs will require much more cross-disciplinary research on human-dominated ecosystems, the authors conclude: "A wide array of skills will be needed to better manage our planet's landscapes and balance human needs, the integrity of ecological infrastructure, the continued flow of ecosystem services and the long-term health of people and the biosphere."
The report also was co-authored by Carnegie Institution researcher Gregory P. Asner, an assistant professor (by courtesy) in Stanford's Department of Geological and Environmental Sciences, and researchers from the University of Maryland, the National Center for Atmospheric Research, the University of Alaska-Fairbanks, the University of Bristol (United Kingdom) and the University of Illinois-Urbana.
Terry Devitt writes about science for the University of Wisconsin-Madison communications office.
