摘要
以湖南会同地区26年生杉木(Cunninghamia lanceolata)人工林为研究对象,探讨剔除林下植被对土壤呼吸和微生物群落结构的影响。2012年6月将林下植被剔除后,2012年7月–2014年7月每月测定一次土壤呼吸速率、5 cm土壤温度和含水量,并分别于2013年7月和2014年7月测定了土壤微生物群落结构和土壤养分数据。研究结果表明:杉木人工林土壤呼吸具有明显的季节变化规律,且与5 cm深处的土壤温度呈极显著的正相关关系。林下植被剔除两年内土壤呼吸平均下降了32.8%,2012年7月–2013年6月下降了42.9%,2013年7月–2014年7月下降了22.2%。根据土壤呼吸与温度拟合的指数方程所计算出的土壤呼吸的温度敏感性Q10值在对照区为2.10,林下植被剔除区为1.87,说明在杉木人工林系统中林下植被剔除2年降低了土壤呼吸的温度敏感性。此外,林下植被剔除也改变了土壤微生物群落结构。林下植被剔除1年后,土壤细菌的浓度没有发生改变,但真菌的浓度降低,导致真菌与细菌的浓度比值下降。此外,革兰氏阳性细菌(G+)的浓度及其与革兰氏阴性菌(G–)的比值升高。林下植被剔除2年后,G+浓度和G+与G–的浓度比值降低。该研究表明林下植被剔除可以降低土壤呼吸,从而减少土壤向大气中释放碳;同时可改变土壤微生物群落结构,而且其效应受作用时间的影响。
Aims Soil respiration （Rs） is the largest fraction of carbon flux in forest ecosystems, but the effects of forest understory removal on Rs in Chinese fir （Cunninghamia lanceolate） plantations is poorly understood. In order to quantify the effects of forest understory removal on Rs and microbial community composition, a field experiment was conducted in a subtropical Chinese fir plantation.Methods Forest understory was removed manually in June 2012. Rs was measured monthly using a LI-COR 8100 infrared gas analyzer from July 2012 through July 2014. Soil temperature and moisture were also measured at 5 cm depth at the time of Rs measurements. Surface soil （0-10 cm） samples were collected in July 2013 and 2014, respectively, and the soil microbial community structures were determined by phospholipid fatty acids （PLFAs） analysis.Important findings Rs decreased by 32.8% over a two-year period following understory removal （UR）, with a greater rate of decrease in the first year （42.9%） than in the second year （22.2%）. The temperature sensitivity of Rs was affected by UR, and was 2.10 and 1.87 in the control and UR plots, respectively. UR significantly reduced the concentration of fungal PLFAs by 18.3%, but did not affect the concentration of bacterial PLFAs, resulting in an increase in the fungal：bacterial ratio; it significantly increased the concentration of gram-positive bacterial PLFAs by 24.5%, and the ratio of gram-positive to gram-negative bacterial PLFAs after one year of treatment, but decreased the concentration of gram-positive bacterial PLFAs by 9.4% and the ratio of gram-positive to gram-negative bacterial PLFAs after two years of treatment. The results suggested that Rs and microbial community composition were both affected by UR in Chinese fir plantation, and the effects were dependent of the duration following the UR treatment.
出处
《植物生态学报》
CAS
CSCD
北大核心
2015年第8期797-806,共10页
Chinese Journal of Plant Ecology
基金
中国科学院战略性先导科技专项(XDB-15010301和XDA05070305)
国家重点基础研究发展计划(2012CB416905)
关键词
CO2通量
杉木人工林
磷脂脂肪酸
温度敏感性
林下植被剔除
CO2 effiux, Cunninghamia lanceolata plantation, phospholipid fatty acid, temperature sensitivity, understory removal
作者简介
通讯作者Author for correspondence （E-mail： qwang@iae.ac.cn）
