碳汇林能够固定大气二氧化碳,在缓解全球变暖中起着重要的作用,研究南亚热带地区不同造林模式碳汇林土壤碳的累积,有助于为不同造林模式的碳汇林土壤碳汇功能评价提供科学依据。采用单因素随机区组设计,对立地条件基本一致的研究区采用新造林(I)、封山育林(II)和补植套种(III)3种造林模式进行碳汇造林,从而研究不同造林模式土壤碳积累与碳汇功能。结果表明:碳汇造林5年期间,土壤全碳含量差异显著,不同造林模式0-20 cm土壤层碳含量差异显著(P<0.05),其变化幅度最大,介于(-0.8611.893)-(3.0211.577)gC/kg之间。经过接近5年的碳汇造林,不同造林模式0-60 cm土壤层碳储量变化量介于(-2.2333.540)-(8.6702.342) Mg C/hm~2之间,其中新造林(I)与补植套种(III)土壤碳储量变化量差异极显著(0.01);碳汇造林5年,土壤碳储量显著增加,各造林模式土壤碳汇量由大到小依次为III > II > I,封山育林(II)和补植套种(III)的土壤碳汇效益显著。采取新造林模式的初始5年,不利于土壤的碳积累,而采取补植套种模式既有利于土壤碳固定,也有利于土壤碳的积累。
英文摘要:
Carbon sink forests can fix atmospheric carbon dioxide and they play an important role in mitigating global warming. Research on the accumulation of soil carbon in carbon sink forests grown using different afforestation models in the South Asian subtropical region will contribute to our understanding of carbon sequestration by carbon sink forests. A singlefactor randomized block design was used to investigate carbon sinks and three afforestation models. These were new afforestation (I), closed mountain afforestation (II), and replanting (III). Soil carbon accumulation and carbon sink function were also investigated. The results showed that the soil total carbon content was significantly different before and after the five-year study period. The soil carbon content in the 0-20 cm soil layer varied significantly among the afforestation models (P<0.05),and the largest variation range was -0.861 1.893 g C/kg to 3.021 1.577 g C/kg. The multiple comparisons of soil organic carbon content showed that the soil organic carbon content in the 0-20 cm layer for the afforestation model was significantly different (P<0.05) from the other two models. In 2016,after nearly five years of carbon sinking and afforestation, there were significant differences in the soil organic carbon contents between the different afforestation models (P < 0.05),especially in the topsoil. The soil carbon stocks in the 0--60 cm soil layer ranged between -2.2333.540 and 8.670 2.342 Mg C/hm~2 for the different afforestation models and the difference in soil carbon stocks between new afforestation (I) and replanting (III) was extremely significant (P<0.01) after the carbon sink trees had been allowed to grow for 5 years. The soil carbon stocks also increased significantly. Between 2012 and 2016,the soil carbon sinks of the various afforestation models were ranked as follows: III>II>I, and the soils after closed mountain afforestation (II) and replanting (III) were significantly better carbon sinks than after model I. The afforestation model has significant effects on soil organic carbon accumulation and carbon sequestration in carbon sink forests. The main differences are caused by root decomposition, litter, and precipitation. The adoption of new afforestation models for the first five years does not improve soil organic carbon. Furthermore, accumulation and fixation do not improve organic carbon levels. Adopting a closed mountain afforestation model does improve soil organic carbon fixation, but does not increase the accumulation of organic carbon. However, the replanting model (III) improves both soil carbon fixation and soil carbon accumulation.