崩岗治理碳汇作用与碳汇能力评估

Assessment on the role and capacity of carbon sink in managed Benggang

为了评估崩岗治理的碳汇能力,在福建省安溪县选择未治理崩岗(UB)为对照,综合治理模式崩岗(MB)和整地造林模式崩岗(AB)为研究对象,分层采集0~10、10~20和20~40 cm土壤样品,使用碳氮分析仪测定土壤有机碳,环刀法测定土壤密度;通过样方法和全面清查法调查树种、胸径、树高,利用生物量方程和收获法测定生物量。结果表明:1)崩岗治理产生明显的保土保碳、减蚀减排和增绿增汇的作用;2)AB的增汇作用以植被碳库提升为主,MB以土壤碳库提升为主;3)AB的碳汇能力高于MB,2种模式的造林及其管护方式是引起碳汇增量差异的主要原因;4)崩岗治理10a左右,拦蓄沙土中的土壤碳密度低于南方红壤区退化土地植被修复后的土壤碳密度,具有较大的提升空间。崩岗治理是防治南方红壤丘陵区水土流失的有效措施,具有明显的保碳减排增汇等作用,研究结果可为今后崩岗治理的模式选择与其碳汇能力评估提供科学支撑。

[Background]Benggang management is an important soil and water conservation measure in the southern red soil region,it plays a crucial role in maintaining ecosystem stability and improving the environment.However,research on the impact of Benggang management on carbon sink is still relatively limited.Thus,the objective of this study is to assess the carbon sink capability of Benggang management in terms of protecting soil and carbon,mitigating erosion and carbon emission,and promoting vegetation and carbon sequestration,as well as the differences in carbon sink capacity among different management models.[Methods]We selected one un-managed Benggang(UB),one Benggang with a comprehensively managed(MB)and three Benggangs with a land cultivation and afforestation Bengang managed(AB)as the research objects in Anxi county,Fujian province.Soil samples were collected at intervals of 0-10,10-20 and 20-40 cm from different depths in all selected Benggangs.SOC(soil organic carbon)was determined using a carbon-nitrogen analyzer.Soil bulk density was measured using the ring knife method.Data on tree species,diameter at breast height,and tree height were obtained through field surveys and sampling methods.The tree biomass was quantified using biomass equations and harvesting methods.[Results]1)Benggang management effectively protect soil and carbon,mitigate erosion and carbon emission,and promote vegetation and carbon sequestration.The carbon conservation,carbon emission reduction,and carbon sequestration capacity of MB are 32.00 t/hm^(2),23.47 t/hm^(2) CO_(2) and 35.86 t/hm^(2) CO_(2),respectively.Those of AB are 3.97-9.42 t/hm^(2) C,2.91-6.91 t/hm^(2) CO_(2) and 73.77-727.98 t/hm^(2) CO_(2),respectively.Based on this calculation,the managed Benggangs may increase carbon sequestration by 399.73×10^(4) t CO_(2) in Anxi county.2)The carbon sequestration effect of AB primarily relies on the enhancement of vegetation carbon stocks,accounting for 51.24%-97.35% of the total carbon sequestration,while for MB,it mainly relies on the enhancement of soil carbon stocks,accounting for 72.39% of the total carbon sequestration.3)The carbon sequestration capacity of AB is higher than that of MB.The main reason for the difference between the two methods is the afforestation and management practices employed.4)After approximately 10 years of Benggang management,the soil carbon density of the managed areas is currently lower than that of degraded following vegetation restoration in the southern red soil region.This suggests that there is considerable potential for improvement in the soil carbon density of Benggang management.[Conclusions]Benggang management serves as a measure to prevent water and soil erosion and promote soil carbon conservation,and to reduce carbon emission,and carbon sequestration in the red soil hilly areas of southern China.The findings may provide scientific support for the selection of future Benggang management models and the assessment of their carbon sequestration capacity.