Abstract:

The effect of soil carbon sink after the implementation of water and soil conservation in the severely eroded red soil granite area in the south is not clear. In order to reveal the impact mechanism of vegetation restoration on the organic carbon pool of degraded soils, the study selected the southern water and soil conservation comprehensive management pilot model-Tangbei small watershed in Xingguo County, Jiangxi Province as the studied area, and set up degraded plots (BL) and horizontal bamboo ditch. The ecological restoration model (F34) of comprehensive implementation of arbor, shrub and grass replanting, front ridge and back ditch+stepped grass planting reverse slope platform orchard development management model (GY) and surrounding undisturbed secondary forest (UF) four types of plots Analyze the changes of total organic carbon (TOC) and soil active organic carbon components at different levels, and evaluate the soil carbon sink effect of comprehensive management of typical granite erosion areas in the south. The results showed that the TOC content of 0-100 cm soil under the F34, GY and UF modes were 5.54, 6.05, 10.22 g∙kg^-1, respectively, which increased by 145%, 168% and 352% compared with BL; the DOC content of 0-40 cm soil were respectively They are 46.29, 45.91 and 116.85 mg∙kg^-1, which are 410%, 405% and 465% more than BL; the soil MBC content is 112.34, 73.20 and 251.99 mg∙kg^-1, which are 217%, 106% and 611 % more than BL; 0-100 cm soil carbon storage in F34 and GY models are 39.65 and 53.91 t∙hm^-2, which are higher than BL (19.86 t∙hm^-2), but lower than the undisturbed UF plot (75.90 t∙hm^-2), the carbon storage of the ecological restoration plot and the orchard development plot were 19.79 and 34.05 t∙hm^-2, respectively, and the carbon storage rate was 0.58 and 1.00 t∙hm^-2∙a^-1, respectively; The current F34 and GY storage rates are estimated to require 62 and 22 years, respectively, to reach the level of soil organic carbon storage equivalent to UF. In summary, the ecological restoration model and the orchard development management model can effectively promote the accumulation and recovery of soil organic carbon, and the orchard model has a more obvious soil carbon recovery effect, but there are still some gaps from the surrounding undisturbed secondary forests; secondly, eroded and degraded land After treatment, the active organic carbon content of the soil has been significantly increased; at the same time, the degraded bare land has a high carbon sink potential, even after 34 years of F34 and GY treatment, it still has a large carbon sink potential.

Key words: soil organic carbon, soil dissolved organic carbon, soil microbial biomass carbon, carbon sequestration, granite erosion area, comprehensive management of soil and water conservation

摘要：

南方红壤花岗岩严重侵蚀区实施水土保持治理后的土壤碳汇效应尚不清晰。为揭示水土保持综合治理对退化土壤有机碳库的影响效应,该研究选取南方水土保持综合治理试点的样板——江西省兴国县塘背小流域为研究区,设置退化样地（BL）、水平竹节沟+乔灌草补植综合施策的生态恢复模式（F34）、前埂后沟+梯壁植草式反坡台地果园开发治理模式（GY）和周边未受扰动的次生林（UF）4种类型样地,分析不同层次土壤总有机碳（TOC）、土壤活性有机碳组分的变化情况,评价南方典型花岗岩侵蚀区综合治理的土壤碳汇效应。结果表明：F34和GY、UF模式下0—100 cm土壤TOC平均含量分别为5.54、6.05、10.22 g∙kg^-1,比BL增加145%、168%和352%;0—40 cm土壤DOC平均含量分别为46.29、45.91和116.85 mg∙kg^-1,比BL增加410%、405%和465%;土壤MBC含量分别为112.34、73.20和251.99 mg∙kg^-1,比BL增加217%、106%和611%;F34和GY模式下0—100 cm土壤碳储量为39.65和53.91 t∙hm^-2,高于BL（19.86 t∙hm^-2）,但低于未受人为干扰的UF样地（75.90 t∙hm^-2）,生态恢复样地和果园开发样地的碳吸存量分别为19.79、34.05 t∙hm^-2,碳吸存速率分别为0.58、1.00 t∙hm^-2∙a^-1;以当前F34、GY吸存速率推算,分别还需要62 a和22 a才能达到与UF相当的土壤有机碳库储量水平。综上,生态恢复模式和果园开发模式可有效促进土壤有机碳积累和恢复,且果园模式土壤碳素恢复效应更加明显,但距离周边未受扰动的次生林还存在一些差距;其次,侵蚀退化地经治理后,显著增加了土壤活性有机碳含量;同时退化裸地具有较高的碳汇潜力,即使通过F34、GY治理34 a后仍具有较大碳汇潜力。

关键词: 土壤有机碳, 可溶性有机碳, 微生物生物量碳, 碳吸存, 花岗岩侵蚀区, 水土保持综合治理