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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。
With the purpose of short-term vegetation change affecting 13C enrichment of soil profile and soil carbon cycling mechanism revealed by these enrichment phenomena, five groups of mountain soil profiles were selected to study vegetation succession in Qujing, Yunnan Province. Five stable carbon isotope ratios (δ13C), total organic carbon (TOC) and carbon density, and compared their differences. The results showed that short-term vegetation change (about 10 years) had a significant effect on the δ13C value of 0 ~ 30 cm layer in the soil profile, of which the effect was greatest on the 0 ~ 10 cm layer. The δ13C changes of soil organic matter after shrubs were replaced by forests and grasslands were 2.28 ‰ and 5.08 ‰, respectively. The δ13C value of 30-50 cm soil layer is insensitive to vegetation change, which can be used as the reference profile layer of soil profile. The change of δ13C in the atmosphere is not the main reason for the 13C enrichment in the 0-50 cm profile layer of forest soil as the depth decreases. In 10 years, the vegetation changed from shrubs to artificial oak trees or from shrub vegetation to herbaceous vegetation. The changes of organic carbon density in 0-30 cm soil profile were 2.30 kg / m2 and -1.00 kg / m2, respectively. The rate of change of vegetation density from shrub to planted oak was 0.230 kg / m2 / a, which is of great importance to change the carbon density of mountainous soil and increase carbon storage in the short term. δ13C has good discriminating power in the short-term succession of C3 vegetation, which can be used as a research tool for soil carbon pool replacement and carbon cycle.