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March 13, 2006

To avoid doing more harm than good, land trusts must consider market forces when acquiring property

Land trusts that focus on biodiversity conservation should consider the impact of real estate market forces when acquiring land, according to a new study in the Proceedings of the National Academy of Sciences (PNAS). Without good data and an understanding of the laws of supply and demand, land trusts risk doing more harm than good for biodiversity, the authors say.

"Land Market Feedbacks Can Undermine Biodiversity Conservation" is scheduled to be published this week on the PNAS website (

"Until recently, conservation buyers were a very small part of the land market—they didn't have much impact," says Gretchen Daily, professor of biological sciences at Stanford University and co-author of the study. "But now there are over 1,500 land trusts operating in the United States, and together they can change land prices and patterns of development."

The full or partial purchase of land has become a cornerstone of efforts to conserve biodiversity in countries with strong private property rights, the authors write, but harm arises when land trust activity elevates land prices and displaces development onto lands where conservation is needed.

"Land trusts have become so powerful that their collective purchases could actually backfire by drawing development toward sites with high conservation value," Daily explains. "Protecting lands that lack biodiversity is not only a waste of money but undermines future opportunities by increasing development pressure on unprotected lands."

Market feedbacks

For the study, lead author Paul Armsworth of Sheffield University, Peter Kareiva of the Nature Conservancy, James Sanchirico of Resources for the Future and Daily conducted an economic analysis of land-buying practices based on a variety of assumptions about where biodiversity resides. They found that market feedbacks can be especially worrisome if lands outside of nature reserves have considerable ecological value, and if there are developers keen to capitalize on amenities that result from conservation.

"Land trusts are good at integrating biological, recreational and other considerations in setting priorities for making purchases," Daily says. "Now, for the first time, it's becoming important to factor in land market dynamics as well, or well-intentioned actions may do more harm than good."

Land trusts have invested billions of dollars on private land conservation in recent years, according to the authors, particularly the Nature Conservancy, the world's largest land trust, which has spent about $6 billion in the last 50 years to protect more than 16 million acres of private land in the United States.

"With that level of investment, it is time for conservationists to heed economic forces with the same vigor they heed biodiversity trends," Daily says. "The ecological value of lands outside nature reserves and the importance of accurate species inventories cannot be overstated if we are to pursue conservation in a responsible manner. These results provide a compelling demonstration of the need for land trusts to become more economically savvy in their operations."

The study was supported by the Nature Conservancy's Smith Senior Fellows program, the Nuffield Foundation, the British Ecological Society and Resources for the Future.

Editor Note:

The study, "Land Market Feedbacks Can Undermine Biodiversity Conservation," is scheduled to be published online the week of March 13 on the PNAS website:



Mark Shwartz, News Service: (650) 723-9296,


Gretchen Daily, Department of Biological Sciences: (650) 723-9452,

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