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.