Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 2010 Jan 12;107(2):940-5. doi: 10.1073/pnas.0911131107. Epub 2009 Dec 22.
Protected areas are crucial for biodiversity conservation because they provide safe havens for species threatened by land-use change and resulting habitat loss. However, protected areas are only effective when they stop habitat loss within their boundaries, and are connected via corridors to other wild areas. The effectiveness of protected areas is threatened by development; however, the extent of this threat is unknown. We compiled spatially-detailed housing growth data from 1940 to 2030, and quantified growth for each wilderness area, national park, and national forest in the conterminous United States. Our findings show that housing development in the United States may severely limit the ability of protected areas to function as a modern "Noah's Ark." Between 1940 and 2000, 28 million housing units were built within 50 km of protected areas, and 940,000 were built within national forests. Housing growth rates during the 1990s within 1 km of protected areas (20% per decade) outpaced the national average (13%). If long-term trends continue, another 17 million housing units will be built within 50 km of protected areas by 2030 (1 million within 1 km), greatly diminishing their conservation value. US protected areas are increasingly isolated, housing development in their surroundings is decreasing their effective size, and national forests are even threatened by habitat loss within their administrative boundaries. Protected areas in the United States are thus threatened similarly to those in developing countries. However, housing growth poses the main threat to protected areas in the United States whereas deforestation is the main threat in developing countries.
保护区对于生物多样性的保护至关重要，因为它们为那些受到土地利用变化和由此导致的栖息地丧失威胁的物种提供了安全的避难所。然而，只有当保护区能够阻止其边界内的栖息地丧失，并通过走廊与其他野生区域相连时，它们才是有效的。保护区的有效性受到发展的威胁；然而，这种威胁的程度尚不清楚。我们从 1940 年到 2030 年汇编了详细的住房增长数据，并量化了美国大陆上每个荒野地区、国家公园和国家森林的增长情况。我们的研究结果表明，美国的住房开发可能会严重限制保护区作为现代“诺亚方舟”的功能。在 1940 年至 2000 年期间，在美国保护区 50 公里范围内建造了 2800 万套住房，在国家森林内建造了 94 万套住房。在保护区一公里范围内，20 世纪 90 年代的住房增长率（每十年 20%）超过了全国平均水平（13%）。如果长期趋势持续下去，到 2030 年，在美国保护区 50 公里范围内还将再建造 1700 万套住房（100 万套在 1 公里范围内），这将大大降低它们的保护价值。美国的保护区越来越孤立，周围的住房开发正在缩小它们的有效面积，国家森林甚至受到其行政边界内的栖息地丧失的威胁。因此，美国的保护区面临着与发展中国家类似的威胁。然而，在美国，住房增长对保护区构成了主要威胁，而在发展中国家，森林砍伐是主要威胁。
