Dynamic characteristics of dissolved organic carbon release from the mixed leaf litter decomposition of coniferous and broad-leaved tree species
In order to adjust the structure of inefficient Pinus massoniana(P)forest and explore the dynamic changes for dissolved organic carbon(DOC)during the mixed decomposition process of P.massoniana and native broad-leaved tree species.Our research focuses on the leaf litter of P.massoniana,Cinnamomum camphora(C)and Toona sinensis(T),and combine them into the 15 treatments(3 single tree treatments+12 mixed treatments)according to different tree species combinations and mass proportions,and then conducted field decomposition experiments to further explore the optimal tree species combination and the proportion of mixed planting for DOC release.The results were as follows:(1)DOC content of Pinus massoniana and most of mixed treatments(except for PT64)significantly increased during the early stages of decomposition(0-6 months),leading to carbon enrichment.The DOC content of leaf litter decreased with the extension of decomposition time,and also exhibited carbon enrichment in small degree during the middle to late stages of decomposition(12-18 months)or the late stages of decomposition(18-24 months).Mixed leaf litter showed that the higher the proportion of broad-leaved,the lower the DOC content in the later stage.(2)The antagonistic effect of DOC release rate in the early stage of decomposition(0-6 months)was strong(58.33%),and only 8.33%(1/12)of mixed treatments showed the synergistic effect.Its synergistic effect gradually strengthened(91.67%)after 6-18 months,but the synergistic effect of leaf litter(66.67%)during the late stage of decomposition weakened(18-24 months).Among all mixed treatments,PT64 exhibited synergistic effects throughout the entire decomposition stage,followed by PT73,PCT622 and PCT613(3/4).(3)Partial least-squares(PLS)regression showed that N content,P content,lignin content,condensed tannin content,C/N,C/P,lignin/N,and lignin/P were important quality factors affecting the release of DOC from litter in this study area.Overall,the DOC release from mixed Pinus massoniana and broad-leaved leaf litter is affected by tree species,mixed proportion and decomposition time.Compared to other mixed treatments,the proportion of broad-leaved greater is than or equal to 30.00%and the mixed leaf litter treatments including Toona sinensis(PT64,PT73,PCT622 and PCT613)show strong synergistic effects for DOC release.
万方数据
维普
