Data from: Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, have high rates of carbon dioxide evasion and they contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8ºN to 42.8ºS, using litter mixtures of local species differing in quality and phylogenetic diversity, and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, while variation in breakdown of litter mixtures was explained mainly by litter quality and phylogenetic diversity. The influence of these litter variables and pH was modulated by temperature, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.

植物凋落物分解（Plant litter breakdown）是陆地与淡水生态系统中的核心生态过程。其中，溪流与河流的二氧化碳逸出速率颇高，对全球碳通量贡献显著。然而，目前关于淡水生境中植物凋落物分解的不同驱动因子的相对作用的相关研究信息极少，尤其是在大尺度范畴内。本研究开展了一项针对溪流凋落物分解的全球尺度研究，旨在对比生物、气候及其他环境因子对分解速率的影响。研究团队在覆盖北纬47.8°至南纬42.8°纬度区间的24条溪流中实施了实验：使用质量与系统发育多样性（phylogenetic diversity）存在差异的本地物种凋落物混合体，并以桤木（Alnus glutinosa）作为对照，以控制凋落物性状的变异。研究模型结果显示，桤木的分解过程主要受气候调控，同时受酸碱度（pH）的一定影响；而本地凋落物混合体的分解速率差异则主要由凋落物质量与系统发育多样性所解释。上述凋落物相关变量及酸碱度的影响均受温度调控，这表明不同纬度下可能存在不同的作用机制。本研究结果反映了多因子共同驱动的全球变异格局，但仍存在未被解释的方差，这提示亟需开展更广泛的全球尺度对比研究。