杨树人工林生态系统凋落物生物量及其分解特征  

Litterfall Biomass and Decomposition Characteristics in A Poplar plantation Ecosystem

作　　者：葛晓敏 唐罗忠 王瑞华 李勇 朱玲 贾志远 丁晖[3] GE Xiaomin;TANG Luozhong;WANG Ruihua;LI Yong;ZHU Ling;JIA Zhiyuan;DING Hui(College of Life Science, Nanjing University, Nanjing 210046, China;College of Forestry, Nanjing Forestry University, Nanjing 210037, China;Research Center for Nature Conservation and Biodiversity//State Environmental Protection Key Laboratory on Biosafety,Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China)

机构地区：[1]南京大学生命科学学院,江苏南京210046 [2]南京林业大学林学院,江苏南京210037 [3]环境保护部南京环境科学研究所//国家环境保护生物安全重点实验室,江苏南京210042

出　　处：《生态环境学报》2017年第9期1457-1464,共8页Ecology and Environmental Sciences

基　　金：国家重点研发计划课题(2016YFD0600402);江苏省林业三新工程项目(LYSX[2016]48);国际科技合作项目(2011DFA30490);环保部事业费项目"生物多样性保护专项"

摘　　要：凋落物是森林土壤有机质的主要来源,是森林生态系统物质循环和能量流动的重要载体。而凋落物分解是森林生态系统养分生物地球化学循环的重要过程,是土壤有效养分供应能力的决定因素之一,与森林生产力及可持续生长密切相关。通过研究杨树人工林凋落物生物量及其分解过程,掌握其养分数量及其释放规律,为人工林可持续经营提供重要依据。采用凋落物收集网法和凋落物分解袋法,对长江中下游地区南京市浦口区13年生的杨树(Populus deltoides Bartr.cv."Lux"I-69/55)人工林生态系统凋落物生物量以及不同类型凋落物的分解特征进行了系统研究,结果表明:杨树人工林凋落物生物量约为5t·hm^(-2)·a^(-1),叶片是凋落物的主要成分,占凋落物总量的70%左右;通过Olson指数模型拟合得出的各凋落物的半分解时间及95%分解时间均表现为杨树枯枝>杨树枯叶>混合凋落物>枯死的林下植被>杨树根系。2年连续分解试验表明,凋落物中的N整体上呈先富集后释放的模式,P整体上呈持续富集的模式,K呈早期释放模式,而Ca和Mg的释放模式比较复杂。分解2年后,杨树地上部分凋落物(枯叶和枯枝)养分总释放量(N、P、K、Ca和Mg的总和)为86.1 kg·hm^(-2),养分回归率约为60%;林下植被凋落物养分总释放量为92.3 kg·hm^(-2),养分回归率达75%以上,表明林下植被凋落物是杨树人工林生态系统养分归还的重要组成部分。Litterfall is the main resource of organic matter and plays an important role in nutrient biogeochemical cycling in forest ecosystems.Litterfall decomposition is a crucial process in the cycling of ecosystem elements.This study mainly investigated and studied the litterfall biomass monthly dynamics and litter decomposition characteristics used by litterfall traps and litterfall decomposition bags,respectively,in a poplar(Populus deltoides Bartr.cv.“Lux”I-69/55)plantation ecosystem,in the middle and lower reaches of Yangtze River in China.The results showed that:the annual biomass of litterfall from above-ground part of poplar trees in Pukou was about5t·hm-2·a-1,the main component of litterfall was foliage litterfall.The highest decomposition rate of different litterfalls evaluated by Olson exponential model was roots,followed by understory,mixed litterfalls,foliage and branches.In general,the decomposition rates were inverse to C:N ratios of litterfalls.N contents in different litterfalls showed increased during the initial stage of decomposition,then decreased gradually;P contents showed enrichment,while K contents manifested released directly during decomposition.The patterns of Ca and Mg release were various among different litterfalls.After two years of decomposition,the total nutrient release(total of N,P,K,Ca and Mg)from above-ground part of poplar tree litterfalls and understory litterfall were86.1kg·hm-2and92.3kg·hm-2,respectively;the nutrient return rates reached60%and75%,respectively.The results indicated that poplar litterfalls,especially understory litterfall were the important parts of nutrient return in poplar plantation ecosystems.

关 键 词：杨树人工林 生物量 凋落物分解 养分回归 林下植被 

分 类 号：S718.5[农业科学—林学] X173[环境科学与工程—环境科学]