黔西北次生林优势树种叶片-凋落物-土壤连续体有机质碳稳定同位素特征

Carbon stable isotopic characteristics of organic matter in the leaf-litter-soil continuum of dominant tree species in a secondary forest in northwestern Guizhou

稳定性碳同位素自然丰度(δ13C)能够揭示生态系统长时间尺度的有机碳动态变化,阐明生态系统功能的变化特征。以黔西北次生林14个优势树种为研究对象,测定叶片、凋落物以及根区土壤有机碳含量和δ13C值,分析不同层次碳含量和δ13C丰度之间的相关性。结果表明:14个优势树种叶片碳含量为404.67—487.14 g/kg,总体为针叶树种较高、常绿灌木较低;δ13C值为-31.2‰—-27.1‰,随生活型的变化规律不明显。凋落物碳含量为414.62—561.31 g/kg,与叶片碳含量的变化规律较为一致;δ13C值为-31.5‰—-27.3‰,随树种生活型的变化特征也不明显。根区土壤碳含量为10.02—91.59 g/kg,δ13C值为-26.8‰—-22.5‰,碳含量以光皮桦、银白杨等落叶乔木较高。叶片、凋落物和根区土壤3个层次的碳含量与δ13C丰度之间均呈不显著相关,不同层次的δ13C丰度之间和碳含量之间均为正相关。研究结果有助于反映森林生态系统碳循环过程的关键信息,为森林植被恢复提供理论依据。

The natural abundance of stable carbon isotopes (δ^13C) can reveal the dynamic changes of organic carbon over time and illustrate the characteristics of functional changes in ecosystems. Using 14 dominant tree species in the secondary forest in northwestern Guizhou, the organic carbon contents and δ^13C values in leaves, litter, and root-zone soil were measured to analyze the correlation between carbon content and δ^13C abundance at different levels. The results showed that:the carbon content of leaves of the 14 dominant tree species was 404.67-487.14 g/kg. Generally, the carbon content was higher in conifers and lower in evergreen shrubs. The δ^13C value was -31.2‰ to -27.1‰, and the change with life form was not obvious. The litter carbon content was 414.62-561.31 g/kg, which was consistent with the change of leaf carbon content; the δ^13C value was -31.5‰ to -27.3‰, and the changing characteristics of life form in tree species were not obvious. The carbon content in root-zone soil was 10.02-91.59 g/kg, the δ^13C value was from -26.8‰ to -22.5‰. The carbon content was higher in deciduous trees, such as Rhododendron simsii and Populus alba. There was no significant correlation between the carbon content of leaves, litter, and root-zone soil at different levels and the abundance of δ^13C value. A positive correlation was found between the abundance of δ^13C value and carbon content at different levels. The results could help to reveal fundamental information of the carbon cycle process in forest ecosystems and provide a theoretical basis for forest vegetation restoration.