Data from: Biochemical determinants of litter quality in 15 species of Sphagnum

Background and aims: Sphagnum mosses are ecosystem engineers that create and maintain boreal peatlands. With unique biochemistry, waterlogging and acidifying capacities, they build up meters-thick layers of peat, reducing competition and impeding decomposition. We quantify within-genus differences in biochemical composition to make inferences about decay rates, related to hummock–hollow and fen–bog gradients and to phylogeny.Methods: We sampled litter from 15 Sphagnum species, abundant over the whole northern hemisphere. We used regression and Principal Components Analysis (PCA) to evaluate general relationships between litter quality parameters and decay rates measured under laboratory and field conditions. Results: Both concentrations of the polysaccharide sphagnan and the soluble phenolics were positively correlated with intrinsic decay resistance, however, so were the previously understudied lignin-like phenolics. More resistant litter had more of all the important metabolites; consequently, PC1 scores were related to lab mass loss (R2 = 0.57). There was no such relationship with field mass loss, which is also affected by the environment. PCA also revealed that metabolites clearly group Sphagnum sections (subgenera). Conclusions: We suggest that the commonly stated growth-decomposition trade-off is largely due to litter quality. We show a strong phylogenetic control on Sphagnum metabolites, but their effects on decay are affected by nutrient availability in the habitat.

研究背景与研究目的：泥炭藓属（Sphagnum）植物是构建并维持寒温带泥炭地的生态系统工程师。凭借其独特的生物化学特性、滞水与酸化能力，它们可形成厚达数米的泥炭层，从而抑制竞争者生长并阻碍有机质分解。本研究旨在量化该属内物种间生化组成的差异，以推断其分解速率，并探讨分解速率与泥炭丘-泥炭洼生境梯度、低位沼泽-高位沼泽生境梯度以及系统发育的关联。
研究方法：我们采集了遍布整个北半球的15种泥炭藓属植物的枯落物样本。通过回归分析与主成分分析（Principal Components Analysis, PCA），评估枯落物质量参数与实验室及野外条件下测得的分解速率之间的一般性关联。
研究结果：泥炭藓多糖（sphagnan）与可溶性酚类化合物的浓度均与固有抗分解能力呈正相关，此前未被充分研究的类木质素酚类化合物亦呈现此规律。抗分解能力更强的枯落物所含各类重要代谢物的丰度更高，因此主成分1（PC1）得分与实验室条件下的质量损失率显著相关（决定系数R²=0.57）。但该关联并未出现在野外质量损失率中，后者同时受环境因素影响。主成分分析还显示，代谢物特征可清晰区分泥炭藓属的组（亚属）。
研究结论：我们认为学界普遍提出的生长-分解权衡关系，在很大程度上源于枯落物质量差异。本研究表明泥炭藓属植物的代谢物受强烈的系统发育调控，但其对分解过程的影响会受到栖息地养分有效性的制约。