亚热带米槠林不同更新方式对土壤可溶性有机质降解性的影响  

Effects of different regeneration patterns on soil dissolved organic matter degradation in Cas tanopsis carlesii forests of subtropical China.

作　　者：孙颖 高颖 陈惠 司友涛[1] 鲍勇 焦宏哲 SUN Ying;GAO Ying;CHEN Hui;SI You tao;BAO Yong;JIAO Hong zhe(School of Geographical Science,Fujian Normal University/Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,Fuzhou 350007,China)

机构地区：[1]福建师范大学地理科学学院/湿润亚热带山地生态国家重点实验室培育基地,福州350007

出　　处：《应用生态学报》2020年第4期1073-1082,共10页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(31570606);福建省自然科学基金项目(2019J01282)资助。

摘　　要：可溶性有机质(DOM)的生物降解性影响着土壤有机质的存留和释放,对深入认识森林土壤养分循环意义重大。为探究森林更新对土壤DOM降解特征的影响,选取亚热带地区米槠天然林(NF)、米槠次生林(SF)和米槠人工促进天然更新林(AR)土壤DOM溶液为研究对象,进行室内降解(42 d)试验。结果表明:1)3种林分土壤可溶性有机碳(DOC)的降解率和易降解DOC的比例均为SF>AR>NF;可溶性有机氮(DON)和微生物生物量碳(MBC)是显著影响易降解DOC比例的因子;2)难降解组分占3种林分土壤DOC的大部分(72.3%~94.6%),其周转时间长,有利于稳定土壤有机质(SOC)的形成;3)土壤DOM最初的腐殖化指数(HIXem)会影响易降解DOC的周转时间。DOM光谱结构随降解过程呈现动态变化,说明DOM中易降解组分被消耗完后,微生物会转而降解芳香类和疏水性物质以获取碳源。综上,米槠天然林更新为次生林和人促林后增加了易降解DOC的比例,提高了土壤DOM生物可降解性,不利于SOC的积累。Biodegradability of dissolved organic matter(DOM)affects stabilization and mineraliza tion of soil organic matter,which is of great significance to soil nutrient cycling.In order to explore the effects of forest regeneration on soil DOM degradation,soil DOM solution was sampled in a natural Castanopsis carlesii forest(NF),a secondary forest of C.carlesii(SF),and an artificial assisted regeneration forest of C.carlesii(AR)in a sub tropical area and conducted 42 day laboratory incubation.The results showed that:1)both the degradation rate of soil dissolved organic carbon(DOC)and the ratio of labile DOC were as follows:SF>AR>NF;dissolved organic nitrogen(DON)and microbial biomass carbon(MBC)are the factors significantly affecting the ratio of labile DOC;2)stable DOC accounted for the majority of soil DOC in all the three forest types(72.3%-94.6%),which had long turnover time and contributed to the formation of stable soil organic matter(SOC);3)the initial humification index in emission mode(HIXem)of soil DOM would affect the turnover time of labile DOC.The spectral structure of DOM changed dynamically during the degradation process,indicating that microorganism would turn to degrade aromatic and hydrophobic fractions for carbon source after the depletion of labile DOM.Overall,the transforma tion from NF of C.carlesii into SF and AR could increase the proportion of the easily degradable DOC,and enhance the biodegradability of soil DOM,which were not conducive to the accumulation of SOC.

关 键 词：森林更新 可溶性有机质 生物降解性 光谱特性 

分 类 号：S714[农业科学—林学]