CO_2浓度倍增、高氮沉降和高降雨对南亚热带人工模拟森林生态系统土壤呼吸的影响  

EFFECTS OF CO_2 ENRICHMENT,HIGH NITROGEN DEPOSITION AND HIGH PRECIPITATION ON A MODEL FOREST ECOSYSTEM IN SOUTHERN CHINA

作　　者：邓琦[1,2] 周国逸[1] 刘菊秀[1] 刘世忠[1] 段洪浪[1,2] 陈小梅[1,2] 张德强[1] 

机构地区：[1]中国科学院华南植物园,广州510650 [2]中国科学院研究生院,北京100049

出　　处：《植物生态学报》2009年第6期1023-1033,共11页Chinese Journal of Plant Ecology

基　　金：国家重点基础研究发展计划项目(2009CB421101);国家自然科学基金(30725006;40730102和30700112);广东省自然科学基金(8351065005000001和7006918)

摘　　要：土壤呼吸响应全球气候变化对全球C循环具有重要作用。应用大型开顶箱(Open-top chamber,OTC)人工控制手段,研究了大气CO2浓度倍增、高氮沉降和高降雨处理对南亚热带人工森林生态系统土壤呼吸的影响。结果表明:对照箱、CO2浓度倍增处理以及高氮沉降处理下土壤呼吸速率都具有明显的季节变化,雨季(4～9月)的土壤呼吸速率显著高于旱季(10月至次年3月)(p<0.001);但高降雨处理下无明显的季节差异(p>0.05)。CO2浓度倍增能显著提高土壤呼吸速率(p<0.05),其他处理则变化不大。大气CO2浓度倍增、高氮沉降、高降雨处理和对照箱的土壤呼吸年通量分别为4241.7、3400.8、3432.0和3308.4gCO2.m–2.a–1。但在不同季节,各种处理对土壤呼吸的影响是不同的。在雨季,大气CO2浓度倍增和高氮沉降的土壤呼吸速率显著提高(p<0.05),其他处理无显著变化;而在旱季,高降雨的土壤呼吸速率显著高于对照箱(p<0.05),氮沉降处理则抑制土壤呼吸作用(p<0.05)。各处理的土壤呼吸速率与地下5cm土壤温度之间具有显著的指数关系(p<0.001);当土壤湿度低于15%时,各处理的土壤呼吸速率与地下5cm土壤湿度具有显著的线性关系(p<0.001)。Aims Responses of soil respiration to global change play an important role in global car- bon cycling, but the effects of increasing atmospheric carbon dioxide concentration （[CO2]）, nitrogen （N） deposition and precipitation on soil respiration in subtropical China are unclear. Our objective was to test the effects of increased [CO2], N deposition and precipitation on soil respiration and to determine how they influence soil respiration in subtropical China. Methods A model forest ecosystem was constructed of six tree species native to South China. The species were exposed to four experimental treatments in open-top chambers beginning March 2005. Three chambers were used for elevated [CO2] （CC）, two for high N treatment （NN） and the control （CO） and one for elevated precipitation （HR）. The CC treatment was achieved by supplying additional CO2 from a tank until the chambers had a concentration of （700 ＋ 20） gmol CO2＂mo1-1. The NN treat- ment was achieved by spraying seedlings once a week for a total amount of NH4NO3 of 100 kg N.hm-Z.a-1. The HR treatment was achieved by weekly irrigation with 100 L water. Important findings For two years, soil respiration displayed strong seasonal patterns with higher val- ues observed in the wet season （April to September） and lower values in the dry season （October to March） in the control chambers （CO） and the CC and NN treatments （p〈0.001）. There was no seasonal difference in the HR treatment （p〉0.05）. The CC enrichment affected soil respiration significantly （p〈0.05）, and there were no significant differences in annual CO2 effiuxes between CO and the other two treatments. The annual CO2 effiuxes reached 4 241.7, 3 400.8, 3 432.0 and 3 308.4 g CO2-m-Z.a-1 in the CC, NN, HR and CO treatments, respectively. Soil respiration showed diverse responses between dry and wet seasons under different treatments. Higher soil respiration in the CC and NN treatments occurred in the wet season （p〈0.05）. In the dry season, so

关 键 词：CO2浓度倍增 开顶箱(OTC) 氮沉降 降雨 土壤呼吸 

分 类 号：S714[农业科学—林学]