Data from: Photosynthesis, growth, and decay traits in Sphagnum – a multispecies comparison

Peat mosses (Sphagnum) largely govern carbon sequestration in Northern Hemisphere peatlands. We investigated functional traits related to growth and decomposition in Sphagnum species. We tested the importance of environment and phylogeny in driving species traits and investigated trade-offs among them. We selected 15 globally important Sphagnum species, representing four sections (subgenera) and a range of peatland habitats. We measured rates of photosynthesis and decomposition in standard laboratory conditions as measures of innate growth and decay potential, and related this to realized growth, production, and decomposition in their natural habitats. In general, we found support for a trade-off between measures of growth and decomposition. However, the relationships are not strong, with r ranging between 0.24 and 0.45 for different measures of growth versus decomposition. Using photosynthetic rate to predict decomposition in standard conditions yielded R2 = 0.20. Habitat and section (phylogeny) affected the traits and the trade-offs. In a wet year, species from sections Cuspidata and Sphagnum had the highest production, but in a dry year, differences among species, sections, and habitats evened out. Cuspidata species in general produced easily decomposable litter, but their decay in the field was hampered, probably due to near-surface anoxia in their wet habitats. In a principal components analysis, PCA, photosynthetic capacity, production, and laboratory decomposition acted in the same direction. The species were imperfectly clustered according to vegetation type and phylogeny, so that some species clustered with others in the same section, whereas others clustered more clearly with others from similar vegetation types. Our study includes a wider range of species and habitats than previous trait analyses in Sphagnum and shows that while the previously described growth–decay trade-off exists, it is far from perfect. We therefore suggest that our species-specific trait measures offer opportunities for improvements of peatland ecosystem models. Innate qualities measured in laboratory conditions translate differently to field responses. Most dramatically, fast-growing species could only realize their potential in a wet year. The same species decompose fast in laboratory, but their decomposition was more retarded in the field than that of other species. These relationships are crucial for understanding the long-term dynamics of peatland communities.泥炭藓属（Sphagnum）在北半球泥炭地的碳封存过程中占据主导地位。本研究针对泥炭藓物种的生长与分解相关功能性状开展调查，旨在检验环境与系统发育对物种性状的驱动作用，并探究性状间的权衡关系。我们选取了15种全球分布的重要泥炭藓物种，涵盖4个组（亚属）及多种泥炭地生境类型。通过在标准实验室条件下测定光合速率与分解速率，以表征物种固有生长与分解潜力，并将该结果与物种在自然生境中的实际生长、生产力及分解情况进行关联分析。总体而言，研究结果支持生长与分解之间存在权衡关系，但该关联强度较弱：不同生长指标与分解指标的相关系数r介于0.24至0.45之间。利用光合速率预测标准条件下的分解速率时，决定系数R²仅为0.20。生境与组（系统发育背景）会对物种性状及其权衡关系产生影响。在湿润年份，Cuspidata组与Sphagnum组的物种生产力最高；而在干旱年份，物种间、组间以及生境间的差异均趋于消失。Cuspidata组物种的枯落物通常易分解，但它们在野外的分解过程却受到抑制，这可能与其原生湿润生境中近地表的厌氧环境有关。主成分分析（PCA）结果显示，光合能力、生产力与实验室分解速率的变化方向一致。物种未能完全按照植被类型与系统发育进行聚类：部分物种与同组物种聚为一类，而另一些物种则更倾向于与来自相似植被类型的物种聚类。相较于此前泥炭藓的性状分析研究，本研究涵盖了更广范围的物种与生境类型。研究表明，尽管前人报道的生长-分解权衡关系确实存在，但该关系并不显著。因此，我们认为本研究获得的物种特异性性状数据，可为泥炭地生态系统模型的优化提供支撑。实验室条件下测定的固有性状，在野外环境中的响应模式存在差异。最为显著的是，速生物种仅在湿润年份才能实现其生长潜力。同一物种在实验室中分解较快，但在野外其分解过程相较于其他物种受到更明显的抑制。上述关系对于理解泥炭地群落的长期动态至关重要。