Wildlife Research Group, Anatomy School, University of Cambridge, Cambridge, United Kingdom.
PLoS One. 2012;7(8):e41671. doi: 10.1371/journal.pone.0041671. Epub 2012 Aug 14.
Tropical deforestation and forest fragmentation are among the most important biodiversity conservation issues worldwide, yet local extinctions of millions of animal and plant populations stranded in unprotected forest remnants remain poorly explained. Here, we report unprecedented rates of local extinctions of medium to large-bodied mammals in one of the world's most important tropical biodiversity hotspots. We scrutinized 8,846 person-years of local knowledge to derive patch occupancy data for 18 mammal species within 196 forest patches across a 252,669-km(2) study region of the Brazilian Atlantic Forest. We uncovered a staggering rate of local extinctions in the mammal fauna, with only 767 from a possible 3,528 populations still persisting. On average, forest patches retained 3.9 out of 18 potential species occupancies, and geographic ranges had contracted to 0-14.4% of their former distributions, including five large-bodied species that had been extirpated at a regional scale. Forest fragments were highly accessible to hunters and exposed to edge effects and fires, thereby severely diminishing the predictive power of species-area relationships, with the power model explaining only ~9% of the variation in species richness per patch. Hence, conventional species-area curves provided over-optimistic estimates of species persistence in that most forest fragments had lost species at a much faster rate than predicted by habitat loss alone.
热带森林砍伐和森林破碎化是全球最重要的生物多样性保护问题之一,但仍有大量动植物种群在未受保护的森林残余物中灭绝,其原因仍未得到充分解释。在这里,我们报告了在世界上最重要的热带生物多样性热点之一,中大型哺乳动物的局部灭绝前所未有的速度。我们仔细研究了 8846 个人年的本地知识,以获取巴西大西洋森林研究区域内 196 个森林斑块中 18 种哺乳动物的斑块占有数据,该研究区域面积为 252669 平方公里。我们发现哺乳动物区系中存在惊人的局部灭绝率,在可能存在的 3528 个种群中,只有 767 个种群仍然存在。平均而言,森林斑块保留了 18 种潜在物种占有数中的 3.9 种,并且地理范围已经缩小到其原有分布的 0-14.4%,包括五种已在区域范围内灭绝的大型物种。森林碎片对猎人来说非常容易进入,并且容易受到边缘效应和火灾的影响,从而严重降低了物种-面积关系的预测能力,动力模型仅解释了每个斑块物种丰富度变化的约 9%。因此,传统的物种-面积曲线提供了物种持续存在的过于乐观的估计,因为大多数森林碎片中的物种灭绝速度比仅由栖息地丧失预测的速度要快得多。