C:N:P stoichiometry of leaves and fine roots in typical forest swamps of the Greater Hinggan Mountains, China

Abstract

Investigating ecological stoichiometry of leaves and fine roots of forest swamps in the Greater Hinggan Mountains will improve our understanding of plant nutrient use and material cycling in ecosystems at high latitudes with high sensitivity to climate change. In this study, we collected leaf and fine root samples from 19 dominant and subordinate vascular plant species and measured their C, N and P concentrations in three typical forest swamps (Larix gmelinii-Carex schmidtii, L. gmelinii-Vaccinium uliginosum-moss and L. gmelinii-Ledum palustre-Sphagnum) of the Greater Hinggan Mountains, China. We compared C:N:P stoichiometry in leaves and fine roots among different forest swamp types, plant growth forms, and mycorrhizal types. Standardized major axis regression was performed to examine the relationships between leaf and fine root stoichiometry. The results showed that interspecific variation accounted for the largest proportion of total variation in C:N:P stoichiometry of leaves (42.5%-84.6%). N:P had the highest, C:N had the intermediate, and C:P had the lowest interspecific variation in both leaves and fine roots. L. gmelinii-C. schmidtii forest swamps, which had higher soil nutrient and water availability, had lower C:N and C:P in leaves and fine roots. N:P of all three forest swamps were lower than 10, indicating N limitation in this ecosystem. Herbaceous plants had significantly lower leaf C:P, fine root C:N, and fine root C:P than woody species. Both ectomycorrhizal and ericoid mycorrhizal plants had higher leaf and fine root C:N and C:P than arbuscular mycorrhizal and non-mycorrhizal species, while the C:P of ericoid mycorrhizal plants was significantly higher than that of ectomycorrhizal species. Forest swamp type, plant growth form, and mycorrhizal type all had greater influences on leaf and fine root C:N and C:P rather than N:P. Leaf and fine root C:N, C:P, and N:P were positively correlated, indicating strong coordination between plant above- and below-ground C:N:P stoichiometry.