Sasaki Kiyoshi, Lesbarrères David, Watson Glen, Litzgus Jacqueline
Ecol Appl. 2015 Dec;25(8):2240-54. doi: 10.1890/14-1418.1.
Emissions from smelting not only contaminate water and soil with metals, but also induce extensive forest dieback and changes in resource availability and microclimate. The relative effects of such co-occurring stressors are often unknown, but this information is imperative in developing targeted restoration strategies. We assessed the role and relative effects of structural alterations of terrestrial habitat and metal pollution caused by century-long smelting operations on amphibian and reptile communities by collecting environmental and time- and area-standardized multivariate abundance data along three spatially replicated impact gradients. Overall, species richness, diversity, and abundance declined progressively with increasing levels of metals (As, Cu, and Ni) and soil temperature (T(s)) and decreasing canopy cover, amount of coarse woody debris (CWD), and relative humidity (RH). The composite habitat variable (which included canopy cover, CWD, T(s), and RH) was more strongly associated with most response metrics than the composite metal variable (As, Cu, and Ni), and canopy cover alone explained 19-74% of the variance. Moreover, species that use terrestrial habitat for specific behaviors (e.g., hibernation, dispersal), especially forest-dependent species, were more severely affected than largely aquatic species. These results suggest that structural alterations of terrestrial habitat and concomitant changes in the resource availability and microclimate have stronger effects than metal pollution per se. Furthermore, much of the variation in response metrics was explained by the joint action of several environmental variables, implying synergistic effects (e.g., exacerbation of metal toxicity by elevated temperatures in sites with reduced canopy cover). We thus argue that the restoration of terrestrial habitat conditions is a key to successful recovery of herpetofauna communities in smelting-altered landscapes.
冶炼排放不仅会用金属污染水和土壤，还会导致大面积森林枯死以及资源可用性和微气候的变化。这些同时出现的压力源的相对影响往往未知，但这些信息对于制定有针对性的恢复策略至关重要。我们通过沿着三个空间重复的影响梯度收集环境以及时间和面积标准化的多变量丰度数据，评估了长达一个世纪的冶炼作业导致的陆地栖息地结构改变和金属污染对两栖动物和爬行动物群落的作用及相对影响。总体而言，随着金属（砷、铜和镍）含量、土壤温度（T(s)）的升高以及树冠覆盖率、粗木质残体（CWD）数量和相对湿度（RH）的降低，物种丰富度、多样性和丰度逐渐下降。复合栖息地变量（包括树冠覆盖率、CWD、T(s)和RH）比复合金属变量（砷、铜和镍）与大多数响应指标的关联更强，仅树冠覆盖率就解释了19% - 74%的方差。此外，利用陆地栖息地进行特定行为（如冬眠、扩散）的物种，尤其是依赖森林的物种，比主要水生的物种受到的影响更严重。这些结果表明，陆地栖息地的结构改变以及随之而来的资源可用性和微气候的变化比金属污染本身的影响更强。此外，响应指标的许多变化是由几个环境变量的共同作用所解释的，这意味着存在协同效应（例如，在树冠覆盖率降低的地点，温度升高会加剧金属毒性）。因此，我们认为恢复陆地栖息地条件是冶炼改变地区两栖爬行动物群落成功恢复的关键。
