石漠化治理对土壤中CO2、CH4变化特征及碳汇效应的影响

Effects of rocky desertification control on CO_2,CH_4 variation and carbon sink in soil

为探究石漠化治理对土壤中CO_2、CH_4变化特征及碳汇效应的影响,采用气相色谱法对重庆市南川石漠化治理示范区土壤中CO_2、CH_4浓度进行观测,结合土壤温度、土壤含水率、土壤容重和土壤有机碳对石漠化治理区(试验区)和对比区(未经过石漠化治理的荒草地)进行研究,并用溶蚀量数据估算岩溶区碳汇量。结果显示:土壤中CO2浓度随土壤深度的增加先增加后减小,变化范围为393～7 400mg·L^(-1);而土壤中CH_4浓度随土壤深度的增加先减小后增大,变化范围为1.13～3.42mg·L^(-1)。试验区土壤中CO_2浓度均值为2 131mg·L^(-1),CH4浓度均值为1.94mg·L^(-1);而对比区土壤中CO_2浓度均值为2 338mg·L^(-1),CH_4浓度均值为2.10mg·L^(-1)。土壤温度、土壤有机碳与土壤中CO_2浓度变化趋势呈显著正相关关系,而与土壤中CH_4变化趋势呈显著负相关关系,说明土壤温度和土壤有机碳是影响土壤中CO_2、CH_4浓度的主要因素;土壤温度与土壤中CO2浓度呈正相关关系且相关性随石漠化治理而变弱,说明经过石漠化治理土壤温度对土壤中CO2浓度的影响减弱。试验区岩溶试片溶蚀速率大于对比区,且经过石漠化治理,由岩溶作用产生的碳汇可提高0.66～9.42t·km^(-2)·a^(-1);说明石漠化治理对于岩溶区碳汇起到了促进作用。

In order to explore the effects of rocky desertification control on the changes of CO2 and CH4 in soil and the effect of carbon sink,the CO2 and CH4 concentrations in the rocky desertification control demonstration area of Nanchuan,Chongqing were observed by gas chromatography,The effects of rocky desertification control on the changes of CO2 and CH4 in soil were analyzed combined with soil temperature,soil moisture content,soil bulk density and soil organic carbon in different soil layers in experimental area(the rock desertification control area)and comparison areas(grassland without rocky desertification control),the effect of rocky desertification control on karst sink effect was studied(experimental area)and the amount of karst carbon sink was also estimated using the dissolution data.The results show that,(1)The changes of CO2 and CH4 in soil are different in terms of time and space.The CO2 concentration increased firstly and then decreased with soil depth,and the variation range was 393^-7,400 mg·L^-1,while the CH4 concentration decreased firstly and then increased with soil depth,the variation range was 1.13^-3.42 mg·L^-1.(2)The mean CO2 concentration in the experimental area was 2,131 mg·L^-1,and the mean value of CH4 was 1.94 mg·L^-1,whereas the mean CO2 concentration in the comparison area was 2,338 mg·L^-1 and the mean value of CH4 was 2.10 mg·L^-1.(3)Soil temperature and soil organic carbon had a significantly positive correlation with CO2,but negatively correlated with CH4 in soil,indicating that soil temperature and soil organic carbon are the main factors affecting the concentration of CO2 and CH4 in soil.(4)The relationship between soil temperature and CO2 was positive and the correlation was weakened with the increase of rocky desertification control,indicating that the impact of soil temperature on soil CO2 concentration was weakened after rocky desertification control.(5)The dissolution rate of karst test strip in the experimental area is larger than that in the comparison zone,and after the the treatment of rocky desertification,the carbon sink generated by karst processes can be increased by 0.66-9.42 t·km^-2·a^-1,indicating that the rocky desertification control improves the carbon sink in the karst area.