C ∕ N ratio, stable isotope (<i>δ</i>¹³C, <i>δ</i>¹⁵N), and <i>n</i>-alkane patterns of brown mosses along hydrological gradients of low-centred polygons of the Siberian Arctic

Abstract

Abstract. Mosses are a major component of the arctic vegetation, particularly in wetlands. We present C ∕ N atomic ratio, δ13C and δ15N data of 400 brown-moss samples belonging to 10 species that were collected along hydrological gradients within polygonal mires located on the southern Taymyr Peninsula and the Lena River delta in northern Siberia. Additionally, n-alkane patterns of six of these species (16 samples) were investigated. The aim of the study is to see whether the inter- and intraspecific differences in C ∕ N, isotopic compositions and n-alkanes are indicative of habitat, particularly with respect to water level. Overall, we find high variability in all investigated parameters for two different moisture-related groups of moss species. The C ∕ N ratios range between 11 and 53 (median: 32) and show large variations at the intraspecific level. However, species preferring a dry habitat (xero-mesophilic mosses) show higher C ∕ N ratios than those preferring a wet habitat (meso-hygrophilic mosses). The δ13C values range between −37.0 and −22.5 ‰ (median  =  −27.8 ‰). The δ15N values range between −6.6 and +1.7 ‰ (median  =  −2.2 ‰). We find differences in δ13C and δ15N compositions between both habitat types. For some species of the meso-hygrophilic group, we suggest that a relationship between the individual habitat water level and isotopic composition can be inferred as a function of microbial symbiosis. The n-alkane distribution also shows differences primarily between xero-mesophilic and meso-hygrophilic mosses, i.e. having a dominance of n-alkanes with long (n-C29, n-C31) and intermediate (n-C25) chain lengths, respectively. Overall, our results reveal that C ∕ N ratios, isotopic signals and n-alkanes of studied brown-moss taxa from polygonal wetlands are characteristic of their habitat.