Fortini Lucas B, Cropper Wendell P, Zarin Daniel J
U.S. Geological Survey Pacific Island Ecosystems Research Center, Honolulu, Hawaii, United States of America.
School of Forest Resources and Conservation, University of Florida, Gainesville, Florida, United States of America.
PLoS One. 2015 Aug 31;10(8):e0136740. doi: 10.1371/journal.pone.0136740. eCollection 2015.
At the Amazon estuary, the oldest logging frontier in the Amazon, no studies have comprehensively explored the potential long-term population and yield consequences of multiple timber harvests over time. Matrix population modeling is one way to simulate long-term impacts of tree harvests, but this approach has often ignored common impacts of tree harvests including incidental damage, changes in post-harvest demography, shifts in the distribution of merchantable trees, and shifts in stand composition. We designed a matrix-based forest management model that incorporates these harvest-related impacts so resulting simulations reflect forest stand dynamics under repeated timber harvests as well as the realities of local smallholder timber management systems. Using a wide range of values for management criteria (e.g., length of cutting cycle, minimum cut diameter), we projected the long-term population dynamics and yields of hundreds of timber management regimes in the Amazon estuary, where small-scale, unmechanized logging is an important economic activity. These results were then compared to find optimal stand-level and species-specific sustainable timber management (STM) regimes using a set of timber yield and population growth indicators. Prospects for STM in Amazonian tidal floodplain forests are better than for many other tropical forests. However, generally high stock recovery rates between harvests are due to the comparatively high projected mean annualized yields from fast-growing species that effectively counterbalance the projected yield declines from other species. For Amazonian tidal floodplain forests, national management guidelines provide neither the highest yields nor the highest sustained population growth for species under management. Our research shows that management guidelines specific to a region's ecological settings can be further refined to consider differences in species demographic responses to repeated harvests. In principle, such fine-tuned management guidelines could make management more attractive, thus bridging the currently prevalent gap between tropical timber management practice and regulation.
在亚马逊河河口这个亚马逊地区最古老的伐木前沿地带,尚无研究全面探讨随着时间推移多次木材采伐可能产生的长期种群和产量后果。矩阵种群建模是模拟树木采伐长期影响的一种方法,但这种方法常常忽略了树木采伐的常见影响,包括附带损害、采伐后种群统计学变化、适销树木分布的变化以及林分组成的变化。我们设计了一个基于矩阵的森林管理模型,纳入了这些与采伐相关的影响,因此得到的模拟结果反映了重复木材采伐下的林分动态以及当地小农户木材管理系统的实际情况。我们为管理标准(如采伐周期长度、最小采伐直径)设定了广泛的取值范围,预测了亚马逊河河口数百种木材管理方案的长期种群动态和产量,在该地区,小规模、非机械化采伐是一项重要的经济活动。然后,利用一组木材产量和种群增长指标,对这些结果进行比较,以找到最优的林分水平和特定物种的可持续木材管理(STM)方案。亚马逊潮汐洪泛平原森林的STM前景比许多其他热带森林要好。然而,各次采伐之间普遍较高的蓄积恢复率是由于快速生长物种的预计年均产量相对较高,有效地抵消了其他物种预计的产量下降。对于亚马逊潮汐洪泛平原森林而言,国家管理指南既没有为管理中的物种提供最高产量,也没有实现最高的持续种群增长。我们的研究表明,针对一个地区生态环境的管理指南可以进一步细化,以考虑物种对重复采伐的种群统计学反应差异。原则上,这种经过微调的管理指南可以使管理更具吸引力,从而弥合目前热带木材管理实践与监管之间普遍存在的差距。