Do conservation easements work?
Conservation easements – legal agreements that give landowners tax benefits in exchange for forgoing development — have become a common tool for protecting habitat around the world. Just how effective they are, however, has been a subject of some debate. Now comes a study from Wyoming that takes an in-depth look at whether easements are helping save sensitive sagebrush ecosystems.
Big chunks of Wyoming’s arid sage lands have been declared priority areas for conservation by The Nature Conservancy (TNC), a major nonprofit conservation group. As a result, since 1980 TNC has helped numerous landowners in the region place easements on their land. To see if those restrictions were actually reducing development and aiding biodiversity, TNC staffers teamed with ecologists from the University of Wyoming to compare road densities and biodiversity on properties with easements to nearby properties without protection.
In all, the team surveyed 23 properties with easements and 20 properties without, they report in Biological Conservation. Roughly three-quarters were in areas under “high-pressure” for residential development, while the rest faced low development pressure. The researchers measured road densities on the lots, and also conducted plant and animals surveys, measuring things like sagebrush height and density and the presence of animal burrows and fecal pellets from deer and antelope.
One verdict was clear: “Easements are achieving their intended goal of reducing development in areas of Wyoming experiencing increased residential development,” they write. Road densities, for instance, were about 15% less on protected lots, and they also had fewer structures. Easement properties also had “evidence of higher use by some wildlife species (deer, pronghorn, rabbits).” There was little difference between protected and unprotected lots in less-developed areas, however, perhaps because the sample size was too small to capture trends.
There were some things that easements couldn’t prevent, however, including invasion by exotic species from surrounding lands. So, “while easements can limit development within their boundaries, plants and animals on these properties are also affected by conditions within the surrounding landscape,” the authors note. And protected lands in high pressure areas also had fewer mammal burrows, perhaps because local cats and dogs were eating the animals.
While the Wyoming results are encouraging, “we must be cautious about extrapolating our results to other places,” the authors conclude. “Our study was completed for TNC easements in sagebrush ecosystems of the US; findings may differ for other ecosystems, other types of easements, and for other private land protection mechanisms.” – David Malakoff | November 16, 2010
Source: Pocewicz, A., Kiesecker, J., Jones, G., Copeland, H., Daline, J., & Mealor, B. (2010). Effectiveness of conservation easements for reducing development and maintaining biodiversity in sagebrush ecosystems. Biological Conservation DOI: 10.1016/j.biocon.2010.10.012
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