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 过度开发是引发生物多样性丧失与局部灭绝的主要诱因之一。在巴西亚马逊地区，高价值木材树种的高强度开发正导致其种群数量持续下降。当这类树种的种群出现衰退后，往往会被开发可行性更强的低价值常见树种所替代。本研究对亚马逊中部一处可持续发展保护区（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，简称S），评估居民对木材开发的发生情况与开发目的的认知，并识别白沙林（white-sand forests）与旱生林（terra-firme）中可能濒临灭绝的树种。此外，为推断伐木活动可能带来的生态后果，本研究通过保护区内开展的森林样地清查，评估了居民提及的木材树种当前的种群现状。认知显著性指数值与受访者报告显示，研究区域正高强度开发旱生林木材树种，且白沙林树种的开发利用近期呈现明显增长趋势——这类树种此前因商业价值相对较低而未被大规模开发。清查结果表明，与旱生林树种形成鲜明对比的是，白沙林木材树种具有较高的相对密度与较低的S指数值，而旱生林树种大多相对密度较低、S指数值较高。本研究结果凸显了两项核心需求：一是需对旱生林与白沙林中的相关木材树种开展系统性识别与动态监测，二是应提升当地社区对伐木管理实践制定工作的参与度。