Logging impact on Amazonian white-sand forests: perspectives from a sustainable development reserve

ABSTRACT Overexploitation is one of the main causes of biodiversity loss and local extinction. In the Brazilian Amazon, the intensive use of high-value timber species is leading to a decline in their populations. When in decline, these species can be replaced by less valuable and more common ones that are more feasible to exploit. We conducted interviews with residents of two communities in a sustainable development reserve in central Amazonia, and used free lists and the cognitive salience index (S) to assess the perceptions of residents regarding the occurrence and purpose of timber exploitation, and to identify possible endangered species in white-sand and terra-firme forests. In addition, to infer possible consequences of logging, we assessed the current population status of timber species cited by residents in forest-plot inventories carried out within the reserve. S-index values and interviewee reports suggested an intensive use of terra-firme timber species and an apparently recent increase in the exploitation of white-sand species, which did not use to be exploited because of their relatively low commercial value. The inventories showed that the white-sand timber species have high relative densities and low S values in contrast to the terra-firme species, which mostly have low relative densities and high S values. Our results highlight the need to identify and monitor relevant timber species in both terra-firme and white-sand forests, and to increase the involvement of the local community in the development of logging management practices.

摘要 过度采伐是生物多样性丧失与局部灭绝的主要诱因之一。在巴西亚马孙地区，对高价值木材树种的高强度采伐正导致其种群数量下降。当这些树种种群衰退后，往往会被商业价值更低、更常见且更易于采伐的树种所取代。本研究对亚马孙中部某可持续发展保护区（sustainable development reserve）内的两个社区居民开展访谈，采用自由列举法（free lists）与认知显著性指数（cognitive salience index，S），评估居民对木材采伐行为的发生情况与实施目的的认知，并识别白砂林（white-sand forest）与terra firme森林（terra-firme forest）中的潜在濒危树种。此外，为推断采伐活动可能引发的生态后果，本研究通过保护区内开展的森林样地清查（forest-plot inventories），对居民提及的木材树种的当前种群状况进行了评估。认知显著性指数值与受访者反馈均显示，当地对terra firme森林木材树种的采伐强度较高，且近期对白砂林树种的采伐规模明显扩大——这类树种此前因商业价值偏低而未被规模化采伐。森林样地清查结果显示，与terra firme森林树种（多数具备较低的相对密度与较高的认知显著性指数值）形成显著反差的是，白砂林木材树种的相对密度较高，而认知显著性指数值较低。本研究结果凸显了两项核心需求：一是需对terra firme森林与白砂林内的相关木材树种开展系统性识别与动态监测；二是应推动当地社区更深程度参与采伐管理方案的制定与落地工作。