Iglesias-Merchan Carlos, Ortiz-Urbina Esther, Ezquerro Marta, Diaz-Balteiro Luis
Department of Forest and Environmental Engineering and Management, Universidad Politécnica de Madrid, Madrid, Spain.
CENERIC Research Centre, Tres Cantos, Spain.
PeerJ. 2019 May 16;7:e6922. doi: 10.7717/peerj.6922. eCollection 2019.
The potentially negative effects of timber harvesting on biodiversity and habitat conservation leads to the consideration of a wide range of restrictions to forest logging in natural areas. In particular, high noise levels produced by forest machinery present a challenge to developing sustainable forest management plans. The Cinereous vulture (), the largest bird of prey whose nests are located in mature trees, is considered to be appropriate as an indicator species for environment-friendly forest planning. In this work, we evaluated spatially differences in sound propagation between stands. We hypothesized that differences due to the influence of orography in mountainous forests would allow the relaxation of spatial and temporary restrictions to timber logging, without causing any great disturbance at nesting sites of sensitive species.
Our study was conducted in a Scots pine () forest of Spain, where an important colony of the Western European population of Cinereous vulture is located. We built 62 noise maps to characterize noise pollution due to tree logging at planning level. We modeled two different scenarios, in order to characterize; (i) the effect of a chainsaw operator during a complete cycle for felling a tree (Scenario 1), and (ii) the effect of the peak level produced by the breaking noise emitted by the trunk of the tree and its impact on the ground (Scenario 2). A strategy of three logical steps was designed; (i) landscape-scale analysis of noise propagation in stands, (ii) hierarchical cluster analysis of stands, (iii) assessment of the potentially significant influence of noise management in timber harvesting.
The minimum distance () from chainsaw operator sites to the 40 dB(A) contour lines was the only variable that had a significant influence on the clustering results. On the other hand, mean values of a newly proposed metric called average radius or radial distance (ARD) oscillated between 174 m in cluster #1 (Scenario 1) and 407 m in cluster #2 (Scenario 2).
Our results highlight the convenience of considering noise modeling tools at a forest planning level in order to address the compatibility of forest logging and the necessity of protecting nature. We found that spatial propagation of noise made by chainsaws at felling sites does not differ between stands even in a mountainous terrain, contrary to what we initially hypothesized. However, temporary logging restrictions could be excluded in about 36% of the current conditioned management areas according to results in Scenario 2 (400 m). This proposal could be based on a sound pressure level (in decibels) criteria instead of conventional buffer protection distance criteria. In addition, it is suggested that the current size of restricted management areas could be generally extended from a 100 m radius to a 200 m one around the Cinereous vulture nest sites.
木材采伐对生物多样性和栖息地保护可能产生的负面影响，促使人们考虑对自然区域的森林采伐实施广泛的限制。特别是，森林机械产生的高噪音水平对制定可持续森林管理计划构成了挑战。秃鹫是最大的猛禽，其巢穴位于成熟树木中，被认为是环境友好型森林规划的合适指示物种。在这项研究中，我们评估了林分间声音传播的空间差异。我们假设，由于山区森林地形的影响而产生的差异，将允许放宽木材采伐的空间和时间限制，而不会对敏感物种的筑巢地点造成太大干扰。
我们的研究在西班牙的一片苏格兰松林进行，这里是西欧秃鹫种群的一个重要栖息地。我们绘制了62张噪音地图，以在规划层面描述伐木造成的噪音污染。我们模拟了两种不同的情景，以描述：（i）电锯操作员在砍伐一棵树的完整周期中的影响（情景1），以及（ii）树干断裂发出的噪音产生的峰值水平及其对地面的影响（情景2）。我们设计了一个包含三个逻辑步骤的策略：（i）林分中噪音传播的景观尺度分析，（ii）林分的层次聚类分析，（iii）评估噪音管理在木材采伐中的潜在重大影响。
电锯操作员所在位置到40分贝（A）等值线的最小距离是唯一对聚类结果有显著影响的变量。另一方面，一个新提出的指标——平均半径或径向距离（ARD）的平均值在聚类#1（情景1）中为174米，在聚类#2（情景2）中为407米之间波动。
我们的结果强调了在森林规划层面考虑噪音建模工具的便利性，以解决森林采伐的兼容性和保护自然的必要性。我们发现，即使在山区地形中，伐木地点电锯产生的噪音的空间传播在林分之间也没有差异，这与我们最初的假设相反。然而，根据情景2（400米）的结果，在当前约36%的受限管理区域中可以排除临时伐木限制。该提议可以基于声压级（分贝）标准，而不是传统的缓冲区保护距离标准。此外，建议将秃鹫巢穴周围受限管理区域的当前半径从100米普遍扩大到200米。
