Bigger isn’t always better for conservation areas. Big parks may look good on a map, but they often do little to preserve nature’s rich diversity of trees, birds, mammals, and other creatures.

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Large areas with the least value to humans are often protected. These are not necessarily areas where preservation does the most for conservation, suggests a recent study by Lisette Cantú-Salazar and Kevin J. Gaston of the University of Sheffield in the United Kingdom.

The researchers studied 63 protected zones of 25,000 square kilometers. That’s roughly 15,500 square miles, or the size of Vermont.

Vast tracts of icy, barren or otherwise species-poor land are more frequently protected than areas with high biodiversity and rare species, the researchers said.

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Some large reserves do contain biodiversity hotspots or unique ecosystems, such as the Guianan Highlands Moist Forests, the Tibetan Plateau Steppe, and the Eastern Himalayan Alpine Meadows.

But even the best conservation areas are only valuable if they are actually protected, the researchers note. Logging, fishing, grazing, mining and climate change all all threats to protected areas.

Cantú-Salazar and Gaston’s research was published in the November issue of Bioscience.

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