Timber isoscapes. A case study in a mountain area in the Italian Alps

BackgroundLocal timber is still one of the main sources of work and income for mountain communities. However, illegal logging is a major cause of deforestation in many countries and has significant impacts on local communities and biodiversity. Techniques for tracing timber would provide a useful tool to protect local timber industries and contribute to the fight against illegal logging. Although considerable progress has been made in food traceability, timber provenance is still a somewhat neglected research area. Stable isotope ratios in plants are known to reflect geographical variations. This study reports accurate spatial distribution of δ18O and δ2H in timber from north-eastern Italy (Trentino) in order to trace geographical origin.Methodology and principal findingsWe tested the accuracy of four kriging methods using an annual resolution of δ18O and δ2H measured in Picea abies. Pearson’s correlation coefficients revealed altitude to be the most appropriate covariate for the cokriging model, which has ultimately proved to be the best method due to its low estimation error.ConclusionsWe present regional maps of interpolated δ18O and δ2H in Picea abies wood together with the 95% confidence intervals. The strong spatial structure of the data demonstrates the potential of multivariate spatial interpolation, even in a highly heterogeneous area such as the Alps. We believe that this geospatial approach can be successfully applied on a wider scale in order to combat illegal logging.

研究背景：本土木材仍是山地社区主要的就业与收入来源之一。然而，非法采伐是多国森林砍伐的核心诱因，对当地社区及生物多样性造成显著负面影响。木材溯源技术可为保护本土木材产业、助力打击非法采伐提供关键实用工具。尽管食品溯源领域已取得长足进展，但木材产地溯源仍是相对被忽视的研究方向。众所周知，植物体内的稳定同位素比值可反映地理分布差异。本研究测定了意大利东北部特伦蒂诺（Trentino）地区欧洲云杉（Picea abies）木材中δ¹⁸O与δ²H的精准空间分布特征，以实现木材地理来源溯源。研究方法与主要发现：本研究以年分辨率的欧洲云杉木材δ¹⁸O与δ²H实测数据为基础，测试了四种克里金（kriging）插值方法的精度。皮尔逊相关系数（Pearson’s correlation coefficients）分析结果显示，海拔是协同克里金（cokriging）模型的最优协变量，该模型因估计误差最低，最终被证明为最佳插值方法。研究结论：本研究绘制了欧洲云杉木材中经插值得到的δ¹⁸O与δ²H的区域分布图，并同步给出了95%置信区间。数据呈现出显著的空间结构特征，表明即使在阿尔卑斯山这类高度异质性区域，多变量空间插值法仍具备良好的应用潜力。我们认为，该地理空间分析方法可在更大范围内推广应用，以有效打击非法采伐活动。