C/N ratio, stable isotope (δ13C, δ15N), and n-alkane patterns of brown mosses along hydrological gradients of low-centred polygons of the Siberian Arctic

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‰ (medianD..27.8 ‰). The δ15N values range between ..6.6 and C1.7‰(medianD..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 xeromesophilic 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.