Leaf litter carbon, nitrogen and phosphorus stoichiometry of Chinese fir (Cunninghamia lanceolata) across China

The stoichiometric characteristics of plant tissue (living or dead) can influence carbon (C) and nutrient dynamics in forest ecosystems. Numerous investigations have focused on green leaves in site or regional areas, but few on leaf litter, especially for tree species with a wide distribution. Here, we collected 57 leaf litter samples of Chinese fir from 19 sites across subtropical China and determined the C, N and P concentrations and stoichiometric ratios, and related these leaf litter variables with geographical and climatic variables, as well as with soil chemistry, which were assessed through soil sampling at the 19 sites. The results showed that the mean leaf litter C, N and P concentrations (namely nutrient resorption proficiency, NuRP) were 458.3 +/- 4.0 mg g(-1), 8.9 +/- 0.3 mg g(-1), and 0.46 +/- 0.02 mg g(-1), respectively. The mean C:N, C:P, and N:P ratios were 52.9 +/- 1.9, 1049.8 +/- 43.8, and 19.8 +/- 0.6, respectively. Concentrations of leaf litter N and P were strongly positively correlated with each other (p < 0.001), while no significant correlation was found between the C and N, or C and P concentrations (p>0.05). The leaf litter stoichiometry showed linear or nonlinear relationships with the geographical, climatic and soil chemical variables. Hierarchical partitioning (HP) analysis showed that the geographical and climatic variables explained most of the variation in leaf litter C and N concentrations and in the N:P ratio. Variation in the leaf litter P concentration was mainly regulated by soil chemical variables. Overall, our findings indicated that the resorption proficiency of the leaf litter was at intermediate level for both N and P. The leaf litter stoichiometry of Chinese fir was driven by the geographical location, mean temperature and precipitation conditions and soil nutrient status at a regional scale. Our results provided new insights into the ability of Chinese fir to adapt to future climate conditions, and also increased our understandings of drivers of the elemental biogeochemical cycle. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

The study collected leaf litter samples of Chinese fir from 19 sites in subtropical China and analyzed their C, N, and P concentrations and stoichiometric ratios. The results showed strong positive correlation between leaf litter N and P concentrations, while no significant correlation was found between C and N, or C and P concentrations. Leaf litter stoichiometry was influenced by geographical, climatic, and soil chemical variables, with N and P concentrations mainly explained by geographical and climatic factors, and leaf litter P concentration regulated by soil chemical variables. The findings suggested that Chinese fir leaf litter resorption proficiency was at intermediate level for both N and P, driven by regional geographical location, temperature, precipitation, and soil nutrient status.