Phylogenetic or environmental control on the elemental and organo-chemical composition of Sphagnum mosses?

Abstract

Background and aims Plant litter chemistry is a key driver of decomposition in peatlands. This study explored the relative contributions of phylogeny and environment to litter chemistry of peat mosses (Sphagnum), the key peat-forming plants on earth. Methods Fifteen Sphagnum species, representing three taxonomic sections ACUTIFOLIA, CUSPIDATA and SPHAGNUM, were sampled across a wide range of hydro-geochemical conditions. For all species we characterised chemical composition within (i) inorganic elements, (ii) carbohydrate polymers (iii) noncarbohydrates. Results The variation in carbohydrates was mostly explained by taxonomic section, suggesting phylogenetic conservation of carbohydrate composition. ACUTIFOLIA species invested relatively more in pectins, whereas CUSPIDATA and SPHAGNUM species invested more in hemicellulose. The composition of non-carbohydrates was mainly influenced by environment, except for some constituents for which the variation was more correlated to phylogeny. Finally, the variation in inorganic element concentrations mostly reflected hydro-geochemical conditions within and between peatlands. Conclusions The separation into an environmentally independent, phylogenetically conserved group of compounds (structural carbohydrates) and an environmentally dependent, variable group of compounds (inorganic elements, non-carbohydrates) has important implications both for understanding patterns in and for upscaling of spatially variable ecosystem processes associated with peat decomposition such as carbon sequestration, nutrient cycling and greenhouse gas emissions.

Biochemical determinants of litter quality in 15 species of Sphagnum

“…These results were clearly reflected also in the PCA, but the effects of habitat versus phylogeny are hard to fully separate. Limpens et al (2017) concluded that the composition of the dominant primary metabolites (carbohydrates) in Sphagnum is phylogenetically conserved, while the secondary metabolite composition and nutrient concentration are rather controlled by the environment. Instead, we found a strong phylogenetic control on both primary and secondary metabolites, and environmental control only on the tissue nutrient concentration.…”

“…Instead, we found a strong phylogenetic control on both primary and secondary metabolites, and environmental control only on the tissue nutrient concentration. This discrepancy may result from different analytical approaches; while this study employed more direct and quantitative measures of phenolics quantification, Limpens et al (2017) applied an indirect and less quantitative method of pyrolysate composition analysis.…”

Functional trait evolution in Sphagnum peat mosses and its relationship to niche construction

“…However, the only trait related to height‐above‐water‐table in linear regression models is the litter quality trait of cation exchange capacity that may indicate that the other relationships are nonlinear or which the number of taxa sampled ( N = 15) was insufficient to statistically support linear relationships. Overall, there was support for the often quoted tenet that Sphagnum species growing higher above the water table tend to have lower decomposability, lower productivity and higher litter concentrations of phenolics and pectic polysaccharides (Turetsky et al ., ; Hájek et al ., ; Limpens et al ., ).…”

The Sphagnome Project: enabling ecological and evolutionary insights through a genus‐level sequencing project

“…Extending gene‐to‐trait relationships beyond a single species is necessary for understanding the evolution of ecosystem function in Sphagnum ‐dominated peatlands. Traits important for ecosystem function differ among species, including productivity and resource acquisition, resource allocation such as production of secondary compounds, and decomposition rates (Bengtsson et al ., ; Limpens et al ., ). Therefore, in addition to the intensive within‐species resequencing approach described earlier, the Sphagnome Project includes the sequencing of 31 individuals across 15 species representing the five major clades within Sphagnum (Fig.…”