中亚热带杉木人工林和米槠次生林凋落物添加与去除对土壤呼吸的影响  

Impact of litterfall addition and exclusion on soil respiration in Cunninghamia lanceolata plantation and secondary Castanopsis carlesii forest in mid-subtropical China

作　　者：李晓杰[1,2,3] 刘小飞[1,2,3] 熊德成[1,2,3] 林伟盛[1,2,3] 林廷武[2,3] 施友文 谢锦升[1,2,3] 杨玉盛[1,2,3] 

机构地区：[1]福建师范大学地理科学学院,福州350007 [2]湿润亚热带山地生态国家重点实验室培育基地,福州350007 [3]福建三明森林生态系统与全球变化研究站,福建三明365000 [4]三明市三元区林业局,福建三明365000

出　　处：《植物生态学报》2016年第5期447-457,共11页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31130013和31500-407);国家重点基础研究发展规划(973计划)(2014-CB954003)

摘　　要：在未来大气CO2浓度升高的背景下,植被净初级生产力的增加将促使森林土壤碳输入增多。凋落物是土壤碳库的重要来源,对土壤呼吸会产生重要影响。为了模拟植物净初级生产力提高、凋落物产量增加情景下凋落物对土壤呼吸和土壤碳库的影响,2013年1月到2014年12月,在福建省三明市陈大镇国有林场,在杉木(Cunninghamia lanceolata)人工林和米槠(Castanopsis carlesii)次生林,通过设置去除凋落物、添加凋落物和对照(保留凋落物,不做任何处理)处理,研究了土壤呼吸和土壤碳库的动态变化。研究发现:土壤含水量在10%–25%范围内,土壤呼吸温度敏感性指数(Q10)随着土壤含水量的增加呈递增趋势,当含水量<10%时,由于干旱胁迫打破了土壤呼吸与温度之间的耦合,改变了Q10值,使得Q10值小于1。土壤呼吸与凋落物输入量呈显著的线性正相关关系,杉木人工林对照和添加凋落物处理及米槠次生林对照处理,土壤呼吸与2个月前的凋落物输入量相关性最好。而米槠次生林添加凋落物处理,土壤呼吸与当月的凋落物输入量相关性最好,不同林分凋落物呼吸对土壤呼吸的贡献率不同,米槠次生林凋落物层呼吸年通量明显大于杉木人工林,分别占各林分土壤总呼吸的34.4%和15.1%,添加凋落物后,杉木人工林和米槠次生林的土壤呼吸速率增加,但添加凋落物处理的土壤呼吸年通量与对照的差值小于年凋落物输入量。因此,在未来全球CO2升高背景下,植被碳储量的增加、凋落物增加并没有引起土壤呼吸成倍增加,更有利于中亚热带地区土壤碳吸存。Aims Under elevated atmospheric CO2 concentration, an increase in the net primary production is likely to enhance the amount of litter inputs to forest soil. This study aims to determine the dynamics of soil respiration and soil carbon pool as affected by increased litterfall production. Methods A litterfall manipulation experiment was conducted in Cunninghamia lanceolata plantations and secondary Castanopsis carlesii forest stands in Chenda township of Sanming in Fujian Province, China, from January 2013 to December 2014, with treatments of litterfall exclusion, litter addition, and control（normal litterfall condition）. Important findings（1） The value of temperature sensitivity index（Q10） shows a positive relationship with soil water content in the range 10%–25%, and drops below 1 at water content 10%. Drought stress altered Q10 value and interrupted the coupling between temperature and soil respiration, as it reduced the diffusion of soluble carbonsubstrate and the extracellular enzymes, consequently, limited the microbial activity.（2） Linear regression analysis shows that soil respiration is significantly correlated with monthly litter mass（p 0.05）. In the treatments of the control and litter addition in the Cunninghamia lanceolata stands and that of the control in the Castanopsis carlesii stands, soil respiration was best correlated with litter mass two months ago; in the treatment of the litter addition in the Castanopsis carlesii stands, soil respiration was best correlated with litter mass of the current month.（3） On average, the annual CO2 efflux was significantly reduced by litterfall exclusion, by about（362.0 ± 64.9） g C·m–2·a–1 in the Castanopsis carlesii stands and（96.2 ± 37.3） g C·m–2·a–1 in the Cunninghamia lanceolata stands compared with the control. Litter respiration contributed to 34.4% of soil respiration in the Castanopsis carlesii stands and 15.1% in the Cunninghamia lanceolata stands. Litter addition increased the soil respiration rate in both

关 键 词：杉木人工林 米槠次生林 土壤呼吸 凋落物 土壤呼吸温度敏感性指数(Q10) 

分 类 号：S714[农业科学—林学]