中文摘要：

以短期的植被更替如何影响土壤剖面的13C富集以及这些富集现象揭示的土壤碳循环机理为目的,采集云南省曲靖地区发生植被演替的山地土壤剖面5组,分别测定了稳定碳同位素比值（δ13C）、总有机碳含量（TOC）和碳密度,并比较了它们之间的差异。研究发现：短期植被改变（约10年）对土壤剖面中0~30 cm层的δ13C值具有显著影响,其中对0~10 cm层土壤影响最大。灌木更替为森林和草地后土壤有机质的δ13C变化分别达2.28‰和5.08‰。30~50 cm层土壤δ13C值对植被改变不敏感,该层可以作为土壤剖面的基准剖面层。大气δ13C值变化不是森林土壤0~50 cm剖面层中13C随深度减小而富集的主要原因。10年间,植被从灌木演替为人工种植的麻栎乔木或从灌木植被退化为草本植被,0~30 cm层土壤剖面的有机碳密度改变量分别为2.30 kg/m2和-1.00 kg/m2。而植被从灌木到人工种植麻栎的碳密度改变率为0.230 kg/m2/a,这对改变山地土壤的碳密度、短期增加碳储量具有重要意义。δ13C在C3植被的短期演替过程中具有很好的辨识力,可以作为土壤碳库更替和碳循环的研究工具。

英文摘要：

To investigate the impact of short-term vegetation replacement on the distribution of organic carbon in soil and the mechanism of soil carbon cycle,five types of 0-110 cm mountain soil profiles with Quercus trees,shrubs,grass alterations are collected in Qujing,Yunnan Province,China.Each type of soil profile is divided into 6 layers.Stable carbon isotope ratios（δ13C values）,total organic carbon（TOC） data and carbon density are measured.Results show that：（1） Changes of δ13C values after shrubs replaced by Quercus trees and grass are between 2.28‰ and 5.08‰.（2） Vegetation replacement has the greatest impact on13C in SOM（soil organic matter） in the 0-10 cm soil layer.δ13C value in the soil layer of 30-50 cm depth is not sensitive to vegetation replacement,thus the leached layer can serve as a reference profile.（3） Short-term vegetation replacements（around 10 years） significantly influence δ13C values in the 0-30 cm soil layer.In the 0~50 cm soil layer,enrichment of 13C decreases as the depth increases.In addition,δ13C values have negative correlation with TOC.Change of atmospheric δ13C is not related to 13C enrichment in the 0-50 cm soil layer in the forest.（4） Soil organic carbon density in the 0-30 cm layer has changed by 2.30 kg/m2and-1.00 kg/m2in 10 years after replacement of shrub vegetation by oak plantings and herbaceous vegetation,respectively.（5） Planted oak forest has significant impact on short-term soil carbon diversity and storage increase.In 10 years after the change from shrubs to planted oaks,the annual carbon density has increased by 0.23 kg/m2.This paper concludes that δ13C can be used to distinguish C3 from C4,and even among the different C3 plant（such as arbor,shrubs and herbaceous） changes,hence widely used in the study of soil carbon storage turnover and carbon cycle.