CAJ | 학술논문

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CO_2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、CO_2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).CO_2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CO_2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3308.4 g CO_2·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CO_2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),氮沉降处理则抑制十壤呼吸作用(p<0.05).各处理的土壤呼吸速率与地下5 cm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5 cm土壤湿度具有显著的线性关系(p<0.001).
토양호흡향응전구기후변화대전구C순배구유중요작용.응용대형개정상(Open-top chamber,OTC)인공공제수단,연구료대기CO_2농도배증、고담침강화고강우처리대남아열대인공삼림생태계통토양호흡적영향.결과표명:대조상、CO_2농도배증처리이급고담침강처리하토양호흡속솔도구유명현적계절변화,우계(4-9월)적토양호흡속솔현저고우한계(10월지차년3월)( p<0.001);단고강우처리하무명현적계절차이(p>0.05).CO_2농도배증능현저제고토양호흡속솔(p<0.05),기타처리칙변화불대.대기CO_2농도배증、고담침강、고강우처리화대조상적토양호흡년통량분별위4241.7、3400.8、3432.0화3308.4 g CO_2·m~(-2).a~(-1).단재불동계절,각충처리대토양호흡적영향시불동적.재우계,대기CO_2농도배증화고담침강적토양호흡속솔현저제고(p<0.05),기타처리무현저변화;이재한계,고강우적토양호흡속솔현저고우대조상(p<0.05),담침강처리칙억제십양호흡작용(p<0.05).각처리적토양호흡속솔여지하5 cm토양온도지간구유현저적지수관계(P<0.001);당토양습도저우15%시,각처리적토양호흡속솔여지하5 cm토양습도구유현저적선성관계(p<0.001).
Aims Responses of soil respiration to global change play an important role in global carbon cycling, but the effects of increasing atmospheric carbon dioxide concentration ([CO_2]), nitrogen (N) deposition and precipitation on soil respiration in subtropical China are unclear. Our objective was to test the effects of increased [CO_2], 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 [CO_2] (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 CO_2 from a tank until the chambers had a concentration of (700 ± 20) μmol CO_2·mol~(-1). The NN treatment was achieved by spraying seedlings once a week for a total amount of NH_4NO_3 of 100 kg N·hm~(-2)·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 values 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 CO_2 effluxes between CO and the other two treatments. The annual CO_2 effluxes reached 4 241.7, 3 400.8, 3 432.0 and 3 308.4 g CO_2·m~(-2)·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, soil respiration increased in the HR treatment (p<0.05) and decreased in the NN treatment (p<0.05). We found significant exponential relationships between soil respiration rates and soil temperature and significant linear relationships between soil respiration rates and soil moisture (below 15%).