中亚热带4种不同类型森林凋落叶对土壤非结构性碳水化合物的影响

Effects of foliar litter on the dynamics of soil non-structural carbohydrates in four different forests in the middle subtropical region

非结构性碳水化合物(NSC)是土壤易降解有机质的重要组分,凋落叶作为土壤有机质的重要来源,可调控土壤NSC动态,且可能受到森林类型的重要影响.选取中亚热带米槠(Castanopsis carlesii)天然林、米槠次生林、米槠人工林和杉木(Cunninghamia lanceolata)人工林为研究对象,在一个生长季节分析凋落叶输入后土壤NSC(可溶性糖和淀粉)含量的动态变化.结果表明:4种类型森林中凋落叶与土壤NSC及其组分(可溶性糖和淀粉)的关系表现出明显的时间差异.4种类型森林土壤NSC含量在凋落叶添加初期均表现出显著降低,但之后有明显增加的趋势.相对于米槠天然林中凋落叶添加后土壤NSC含量在8月显著增加,其他3种森林中土壤NSC含量增加的时间明显提前,表现为2种米槠人工林在7月显著增加,杉木人工林中在6月显著增加.添加凋落叶后,米槠天然林土壤NSC含量在8月达到最大值3.50μg/g,米槠人工林和杉木人工林土壤NSC含量分别在7月和8月达到最大值3.78μg/g和4.15μg/g.与天然林和次生林不同,2种人工林土壤可溶性糖含量对凋落叶输入的响应幅度相对较小,但含量更高的土壤淀粉对凋落叶的响应更为显著.可见人工林相对于天然林凋落叶与土壤NSC关系更加紧密,结果可为深入认识中亚热带森林地上-地下生态联系提供一定的基础数据.

Soil non-structural carbohydrates(NSC)are important for soil-labile organic matter.Foliar litter inputs in different forests may control their dynamic patterns because foliar litter is an essential source of soil organic matter.This study aimed to examine the relationship between foliar litter and soil NSC in different forests in subtropical regions.We selected a Castanopsis carlesii natural forest,a C.carlesii secondary forest,a C.carlesii plantation,and a Cunninghamia lanceolata plantation that shared similar soil,landscape,and climatic backgrounds before management.The content dynamics of soil NSC,including soluble sugar and starch,were investigated in treatments with or without foliar litter input during the growing season.The relationship between foliar litter,soil NSC,and its components(soluble sugar and starch)showed clear temporal differences among the four forest types.In the early stages,the input of foliar litter significantly decreased soil NSC content;however,it increased soil NSC content regardless of forest type.A significant increase in soil NSC content was observed after August in the C.carlesii natural forest treated with foliar leaf input,while the increase in soil NSC content in the other three forests occurred significantly earlier;a significant increase was observed after July in the C.carlesii forest and plantation and after June in the C.lanceolata plantation.Moreover,the C.carlesii natural forest displayed the highest value of soil NSC(3.50μg/g)in August in the treatment with litter input.In contrast,the C.carlesii and C.lanceolata plantations showed the highest values(3.78 and 4.15μg/g)in July and August,respectively.Additionally,soil-soluble sugar content showed less sensitive responses to litter input.In contrast,soil starch displayed a higher sensitivity to litter input in the two plantations than in the natural and secondary forests.The results suggest that the relationships between litter and soil NSC in the plantations could be more closely related to those in the natural forests,which provides new insights into understanding the above-and underground ecological connections in the regional forests.