Asner Gregory P, Broadbent Eben N, Oliveira Paulo J C, Keller Michael, Knapp David E, Silva José N M
Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 2006 Aug 22;103(34):12947-50. doi: 10.1073/pnas.0604093103. Epub 2006 Aug 10.
The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest. Across 2,030,637 km2 of the Brazilian Amazon from 1999 to 2004, at least 76% of all harvest practices resulted in high levels of canopy damage sufficient to leave forests susceptible to drought and fire. We found that 16+/-1% of selectively logged areas were deforested within 1 year of logging, with a subsequent annual deforestation rate of 5.4% for 4 years after timber harvests. Nearly all logging occurred within 25 km of main roads, and within that area, the probability of deforestation for a logged forest was up to four times greater than for unlogged forests. In combination, our results show that logging in the Brazilian Amazon is dominated by highly damaging operations, often followed rapidly by deforestation decades before forests can recover sufficiently to produce timber for a second harvest. Under the management regimes in effect at the time of our study in the Brazilian Amazon, selective logging would not be sustained.
巴西亚马逊地区林业产业的长期生存能力取决于健康森林中足够木材蓄积量的维持和增长。通过广泛的高分辨率卫星分析，我们研究了近期伐木作业造成的森林破坏以及采伐木材后4年内被砍伐森林被清除的可能性。在1999年至2004年期间，对巴西亚马逊地区2030637平方公里的区域进行研究发现，至少76%的采伐作业导致了严重的树冠破坏，足以使森林易受干旱和火灾影响。我们发现，16±1%的选择性采伐区域在采伐后1年内被砍伐，木材采伐后的4年里，后续每年的森林砍伐率为5.4%。几乎所有的采伐都发生在主干道25公里范围内，在该区域内，已采伐森林被砍伐的概率比未采伐森林高出四倍。综合来看，我们的研究结果表明，巴西亚马逊地区的采伐作业以高度破坏性为主，通常在森林能够充分恢复以产出可用于二次采伐的木材之前数十年就迅速被砍伐。在我们对巴西亚马逊地区进行研究时实施的管理制度下，选择性采伐无法持续。
