Richardson Vanessa A, Peres Carlos A
Centre for Ecology, Evolution and Conservation, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom.
PLoS One. 2016 Jul 13;11(7):e0159035. doi: 10.1371/journal.pone.0159035. eCollection 2016.
Throughout human history, slow-renewal biological resource populations have been predictably overexploited, often to the point of economic extinction. We assess whether and how this has occurred with timber resources in the Brazilian Amazon. The asynchronous advance of industrial-scale logging frontiers has left regional-scale forest landscapes with varying histories of logging. Initial harvests in unlogged forests can be highly selective, targeting slow-growing, high-grade, shade-tolerant hardwood species, while later harvests tend to focus on fast-growing, light-wooded, long-lived pioneer trees. Brazil accounts for 85% of all native neotropical forest roundlog production, and the State of Pará for almost half of all timber production in Brazilian Amazonia, the largest old-growth tropical timber reserve controlled by any country. Yet the degree to which timber harvests beyond the first-cut can be financially profitable or demographically sustainable remains poorly understood. Here, we use data on legally planned logging of ~17.3 million cubic meters of timber across 314 species extracted from 824 authorized harvest areas in private and community-owned forests, 446 of which reported volumetric composition data by timber species. We document patterns of timber extraction by volume, species composition, and monetary value along aging eastern Amazonian logging frontiers, which are then explained on the basis of historical and environmental variables. Generalized linear models indicate that relatively recent logging operations farthest from heavy-traffic roads are the most selective, concentrating gross revenues on few high-value species. We find no evidence that the post-logging timber species composition and total value of forest stands recovers beyond the first-cut, suggesting that the commercially most valuable timber species become predictably rare or economically extinct in old logging frontiers. In avoiding even more destructive land-use patterns, managing yields of selectively-logged forests is crucial for the long-term integrity of forest biodiversity and financial viability of local industries. The logging history of eastern Amazonian old-growth forests likely mirrors unsustainable patterns of timber depletion over time in Brazil and other tropical countries.
在人类历史上，更新缓慢的生物资源种群一直被过度开发，这是可以预见的，而且往往达到经济灭绝的程度。我们评估了巴西亚马逊地区的木材资源是否以及如何出现这种情况。工业规模伐木前沿的异步推进，使得区域尺度的森林景观有着不同的伐木历史。在未砍伐的森林中，最初的采伐可能具有高度选择性，以生长缓慢、高等级、耐荫的硬木树种为目标，而后来的采伐则倾向于集中在生长迅速、木质较轻、寿命长的先锋树种上。巴西占新热带地区所有原生森林圆木产量的85%，而帕拉州占巴西亚马逊地区所有木材产量的近一半，巴西亚马逊地区是任何国家控制的最大的原始热带木材储备区。然而，首次采伐后的木材采伐在经济上是否有利可图或在人口统计学上是否可持续，人们对此仍知之甚少。在这里，我们使用了从私人和社区所有森林的824个授权采伐区提取的关于约1730万立方米木材、314个物种的合法计划采伐数据，其中446个报告了按木材种类的体积组成数据。我们记录了沿亚马逊东部老化伐木前沿按体积、物种组成和货币价值的木材采伐模式，并根据历史和环境变量对其进行了解释。广义线性模型表明，距离交通繁忙道路最远的相对较新的伐木作业选择性最强，将总收入集中在少数高价值物种上。我们没有发现证据表明采伐后的木材物种组成和林分总价值在首次采伐后能够恢复，这表明在老旧的伐木前沿，商业上最有价值的木材物种会变得可预见地稀少或在经济上灭绝。为了避免更具破坏性的土地利用模式，管理选择性采伐森林的产量对于森林生物多样性的长期完整性和当地产业的财务可行性至关重要。亚马逊东部原始森林的伐木历史可能反映了巴西和其他热带国家随着时间推移木材消耗的不可持续模式。
