不同物候时期华西雨屏区四个树种新鲜凋落物可提取腐殖质碳动态

凋落物的可提取腐殖质碳可随着植物生长节律及物候时期的变化而变化,并进而影响物质循环的过程,为深入了解以凋落物为载体的生态系统物质循环特征,该研究以华西雨屏区麻栎(Quercus acutissima)、楠木(Phoebe zhennan)、柳杉(Cryptomeria fortune)和喜树(Camptotheca acuminate)为对象,通过定点动态收集萌芽期、展叶期、盛叶期和落叶期的不同类型凋落物,分析其可提取腐殖质碳(extractable humus carbon,HC)、胡敏酸碳(humic acid carbon,HAC)、富里酸碳(fulvic acid carbon,FAC)以及胡敏酸碳/富里酸碳(humic acid carbon/fulvic acid carbon,HAC/FAC)的差异。结果表明:相对于其他凋落器官,在同一物候时期凋落叶中的HC和HAC含量都最高,大致都表现为凋落叶>凋落枝>凋落果,且在落叶树种中更为显著;相对于其他时期,展叶期四个树种凋落叶均表现出较高的FAC含量,但不同物候期凋落枝和凋落果的HAC含量以及FAC含量受物种的影响较大。尽管HAC/FAC在各器官间差异并不显著,但落叶树种相同器官的HAC/FAC低于常绿树种,表明落叶树种凋落物富里酸相对含量较高,形成速度相对较快,难降解程度也相对较大。统计分析表明关键时期、物种类型、器官类型及其相互作用对凋落物中HC、HAC、FAC含量和HAC/FAC均具有不同程度的影响,这为进一步深入认识区域生态系统以凋落物为载体的物质循环过程提供了理论依据及新的思路。

Dynamics patterns of extractable humus carbon from newly-shed litter of four tree species at different phenological stages in the Rainy Area of West China

The extractable humus carbon of the litter can change with the rhythm of the plant growth and the phenological period, and then affect the material circulation process. In order to fully understand the features of the litterfall-supported regional ecosystem cycle, Quercus acutissima, Phoebe zhennan, Cryptomeria fortune, and Camptotheca acuminatain were selected in the Rainy Area of West China. Different types of litters in the leaf budding period, leaf expanding period, leaf maturing period, and leaf falling period were dynamically collected through fixed-point analysis of the differences in the extractable humus carbon(HC), humic acid carbon(HAC), fulvic acid carbon(FAC), and humic acid carbon/fulvic acid carbon(HAC/FAC). The results were as follows: The contents of HC and HAC in leaf litter were the highest in the same critical period, and they all showed as leaf litter> twig litter> fruit litter, and also showed that the evergreen tree species was not significant but the deciduous tree species was significant; Compared with other periods, leaf litter of the four tree species exhibited high FAC content during the leaf expanding period, However, HAC content and FAC content of twig litter and fruit litter in phenological stages are greatly affected by species. Humic acid carbon/Fulvic acid carbon(HAC/FAC)in leaf litter of four tree species to characterize the relative content and formation rate of humic acid, fulvic acid during the humification of leaf litter, there was no significant difference between organs, showing that the deciduous tree species had lower HAC/FAC than evergreen tree species. The present study indicates that stage types, species types, organ types and their interactions have different degrees of influence on HC, HAC, FAC content and HAC/FAC in litter. The results provide a theoretical information and a new direction for further understanding the material circulation process of litterfall in the regional ecosystem.