There remains a widespread assumption that concentrating conservation efforts on the protection of isolated reserves is the best way we can safeguard biodiversity. But our work shows that in areas of private land that have already been disturbed -- which dominate much of the tropics -- we need to maintain and protect a wide network of forest areas. Without such a landscape-scale approach we can expect many species to go regionally extinct.
As one of the most comprehensive surveys of the impacts of disturbance on tropical forest biodiversity ever conducted, an international team conducted a detailed analysis of nearly 2,000 species of plants, birds, beetles, ants and bees that were found across more than 300 diverse sites in the Brazilian Amazon.
The researchers found, where forests had been cleared for cattle ranching and agriculture, plant and animal life was impoverished and remaining species invariably consisted of the same subset of the original flora and fauna, overall irrefutable evidence that biodiversity is declining across the tropics.
According to their observations, to preserve maximum species diversity, reserves should not be concentrated in one part of a region, but as a widespread network of forest reserves. These should include secondary forests where no primary forests remain. The colleagues emphasize how remaining areas of undisturbed and recovering forest provided the last refuge for many species unable to withstand the impact of human activity.
There remains a widespread assumption that concentrating conservation efforts on the protection of isolated reserves is the best way we can safeguard biodiversity. But our work shows that in areas of private land that have already been disturbed -- which dominate much of the tropics -- we need to maintain and protect a wide network of forest areas. Without such a landscape-scale approach we can expect many species to go regionally extinct.
To preserve maximum species diversity, reserves should not be concentrated in one part of a region, but as a widespread network of forest reserves. These should include secondary forests where no primary forests remain. Over time this would not only help to conserve the local biodiversity but also save money.
These findings are timely as Brazil recently revised its environmental laws regulating forests, allowing a trading system for private reserves and designing plans for environmental restoration. For example, the high variation in biodiversity found in secondary forests indicates the role these ecosystems play in regional conservation. For many areas of the Amazon, conserving existing secondary forests may be much cheaper and even more efficient than planting trees
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