冻融作用对亚高山森林土壤有机碳组分中不同凋落物源碳贡献的影响  

Contribution of litter-derived carbon to soil organic carbon fractions and its response to freezing-thaw cycling in a subalpine forest

作　　者：张玉 杜婷 陈玉莲 朱和萌 谭波[1] 游成铭 张丽[1] 徐振锋[1] 李晗[1] ZHANG Yu;DU Ting;CHEN Yu-Lian;ZHU He-Meng;TAN Bo;YOU Cheng-Ming;ZHANG Li;XU Zhen-Feng;LI Han(Forestry Ecological Engineering in Upper Reaches of Yangtze River Key Laboratory of Sichuan Province,College of Forestry,Sichuan Agricultural University,Chengdu 611130,China)

机构地区：[1]四川农业大学林学院,长江上游林业生态工程四川省重点实验室,成都611130

出　　处：《植物生态学报》2024年第11期1422-1433,共12页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31901295);中国博士后科学基金(2023M732500和2022M722297);四川省自然科学基金(2024NSFSC0354)。

摘　　要：全球变暖对高海拔地区土壤冻融循环作用的影响日益加剧,而凋落物碳作为森林土壤有机碳的主要来源,其对土壤各有机碳组分的贡献及如何响应冻融循环作用尚不清晰。该研究通过室内模拟冻融循环实验和稳定同位素示踪技术,利用^(13)C标记云杉(Picea asperata)凋落物(根、枝、叶),探究了冻融作用下亚高山森林凋落物源碳对土壤可溶性有机碳(DOC)、微生物生物量碳(MBC)、腐殖质碳(HC)、颗粒有机碳(POC)和矿质结合有机碳(MAOC)的贡献。培养30天后,凋落物碳对土壤POC和MBC的贡献率分别为13.1%和9.0%,显著高于其他有机碳组分;不同类型凋落物对土壤各有机碳组分的贡献差异显著,其中根对POC、MAOC和HC的贡献率显著低于枝和叶。冻融作用显著提高了土壤DOC和MBC中凋落物源碳的贡献率,而降低了土壤POC、MAOC和HC中凋落物碳贡献率。相关性分析结果显示,土壤碳获取相关酶活性与凋落物源碳对土壤有机碳贡献率呈显著正相关关系。表明在亚高山森林凋落物分解初期,冻融作用的发生有利于凋落物源碳在土壤DOC和MBC等活性有机碳组分中的积累,但抑制了其在MAOC和HC等土壤稳定有机碳中的固存。研究结果有助于深入理解森林凋落物归还对土壤有机碳固持的贡献,为全球气候变化背景下亚高山森林土壤碳库的经营管理提供科学依据。Aims The impact of global warming on soil freeze-thaw cycling in high-altitude area is increasing.However,the contribution of litter-derived carbon to various soil organic carbon fractions and its response to freeze-thaw cycling remains unclear.Methods The study utilized an indoor simulated freeze-thaw cycling experiment and stable isotope tracing technique,using^(13)C-labeled Picea asperate litter(root,twig,leaf),to explore the contribution of litter-derived carbon to dissolved organic carbon(DOC),microbial biomass carbon(MBC),humus carbon(HC),particulate organic carbon(POC)and mineral associated organic carbon(MAOC)in soil under freeze-thaw cycles.Important findings The results showed that:after 30 days of incubation,litter-derived carbon significantly contributed to soil POC and MBC,accounting for 13.1%and 9.0%,respectively.The contribution of litter to different soil organic carbon fractions varied among different organs,with roots exhibiting a significantly lower contribution rate to POC,MAOC,and HC compared to twigs and leaves.Under freeze-thaw cycles,litter carbon contributed more to soil DOC and MBC,while showing a lower contribution rate to soil POC,MAOC,and HC.Correlation analysis revealed a significant positive relationship between soil carbon acquisition-related activity enzymes and the contribution of litter-derived carbon to soil organic carbon.These findings indicate that freeze-thaw processes facilitate the accumulation of litter-derived carbon in active organic carbon fractions such as soil DOC and MBC,but inhibit the sequestration of plant-derived carbon in stable soil organic carbon during the initial litter decomposition period in subalpine forests.The research findings contribute to a deeper understanding of the contribution of forest litter return to soil organic carbon fractions,providing a scientific basis for the management and operation of soil carbon pools in subalpine forests under the backdrop of climate change.

关 键 词：冻融作用 凋落物分解 土壤有机碳 δ^(13)C 

分 类 号：S71[农业科学—林学]