Dynamic characteristics of DOC release from the mixed leaf litter decomposition of coniferous and broad-leaved tree spieces

Subjects: Biology >> Botany >> Applied botany submitted time 2023-12-24 Cooperative journals: 《广西植物》

LI Xun ZHANG Yan SONG Simeng ZHOU Yang ZHANG Jian

Abstract： In order to adjust the structure of inefficient Pinus massoniana forest and explore the dynamic changes for 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 and Toona sinensi, and combine them into the 15 treatments (3 single tree treatments + 12 mixed treatments) according to different tree species combinations and mass ratios, and then conducted field decomposition experiments to further explore the optimal combination for DOC release. The results showed that: (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 exhibit 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 leaves, 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 its synergistic effect gradually strengthened (91.67%) after 6-18 months. But the synergistic effect of leaf litter weakened (66.67%) during the late stage of decomposition (18-24 months). Among all mixed treatments, PT64 exhibited synergistic effects throughout the entire decomposition period, followed by PT73, PCT622 and PCT613(3/4). (3) Partial Least-Squares Regression (PLS) showed that N content, P content, lignin content, condensed tannin content, C/N, C/N, lignin/N, and lignin/P were important factors affecting the release of DOC from litter in this study area. Overall, the DOC release from mixed P. massoniana and broad-leaved litter was affected by tree species, mixing ratio and decomposition time. Among all of the mixtures, PT64, PT73, PCT622 and PCT613 showed strong synergistic effects for DOC release.

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