海涂围垦区不同林分土壤活性有机碳垂直变化特征

Vertical Variation Patterns in Soil Labile Organic Carbon in Different Stands in Coastal Reclamation Area

[目的]探索海涂围垦区不同林分土壤有机碳和活性碳组分的垂直分布及其影响机制,为围垦区林分土壤碳库稳定性评价和树种筛选提供科学依据。[方法]以海涂围垦区3种主要林分(美洲黑杨、水杉和银杏)为研究对象,分析0~100 cm深度土壤有机碳、微生物量碳和溶解性有机碳垂直分布特征及其与土壤理化性质和酶活性的关系。[结果]3种林分土壤有机碳、微生物量碳和溶解性有机碳含量均随土层深度增加逐渐降低,其中,0~20 cm土层水杉和美洲黑杨林分土壤有机碳含量显著高于银杏林分,20 cm以下土层3种林分之间差异较小;0~60 cm土层水杉林分微生物量碳和溶解性有机碳含量最高,其次为美洲黑杨林分,银杏林分最低,60 cm以下土层3种林分之间差异较小。土壤溶解性有机碳/土壤有机碳和微生物量碳/土壤有机碳比值均随土层深度增加先增大后减小(除银杏林分土壤溶解性有机碳/土壤有机碳比值在各土层之间无显著差异外),20~60 cm土层3种林分土壤溶解性有机碳/土壤有机碳和微生物量碳/土壤有机碳比值较高,总体上,3种林分土壤溶解性有机碳/土壤有机碳和微生物量碳/土壤有机碳比值在剖面分布差异较小。冗余分析和相关性分析表明,各林分土壤有机碳及活性碳组分与有效氮和蔗糖酶极显著正相关,与土壤pH极显著负相关。[结论]树种显著影响沿海围垦区土壤剖面活性有机碳分布,但对剖面土壤有机碳库稳定性影响较小。试验区美洲黑杨和水杉人工林土壤固碳潜力优于银杏人工林。

[Objective]To provide a scientific basis for the evaluation of soil carbon pool stability and tree species selection in coastal reclamation areas,the vertical variations and potential influence mechanism of soil organic carbon and labile carbon fractions in different stands were investigated.[Method]We studied the vertical distribution characteristics of soil organic carbon,microbial biomass carbon,and dissolved organic carbon and their relationships with soil physicochemical properties and enzyme activities in 0-100 cm depth in Populus deltoides,Metasequoia glyptostroboides and Ginkgo biloba plantations.[Result]The contents of soil organic carbon,microbial biomass carbon and dissolved organic carbon gradually decreased with the increase of soil depth in three stands.The contents of soil organic carbon in the 0-20 cm soil layer were significantly higher in M.glyptostroboides and P.deltoides stands than that in the G.biloba stands,but there was no significant difference in the 20-100 cm soil layer among the three stands.The contents of microbial biomass carbon and dissolved organic carbon in the soil layer of 0-60 cm were the highest in the M.glyptostroboides stand,followed by P.deltoides and G.biloba stands,and there were no significant differences in the 60-100 cm soil layer among the three stands.The ratios of soil dissolved organic carbon/soil organic carbon and microbial biomass carbon/soil organic carbon initially increased and then decreased with the increase of soil depth(except for the ratio of soil dissolved organic carbon/soil organic carbon).The ratios of soil dissolved organic carbon/soil organic carbon and microbial biomass carbon/soil organic carbon were higher in 20-60 cm soil layer.Overall,the ratios of soil dissolved organic carbon/soil organic carbon and microbial biomass carbon/soil organic carbon in the three stands had slight difference in all soil layers.Redundancy analysis and correlation analysis showed that soil organic carbon and labile organic carbon fractions of each stand were significantly positively correlated with soil total nitrogen,hydrolyzable nitrogen and invertase activity,and negatively correlated with soil pH.[Conclusion]Tree species greatly affected the labile organic carbon in the soil profile in coastal reclamation areas,and which has a weak effect on the stability of soil organic carbon.