荒漠草原4种典型植物群落夏季土壤呼吸及枯枝落叶分解释放CO2贡献量

采用动态密闭气室分析法测定了沙蒿（Artemisia desertorum）群落、赖草（Leymus secalinus）群落、甘草（Glycyrrhizauralensis）群落和冰草（Agropyron crisatum）群落4种典型荒漠草原植物群落土壤呼吸和枯落物分解的CO2释放速率（RS＋L）、土壤呼吸CO2释放速率（RS）,利用推导法估算得到了枯落物分解的CO2释放速率（RL）及其对总释放的贡献。得到了如下结论：（1）4种群落的RS＋L差异较大,其平均值大小排序分别为冰草群落〉赖草群落〉甘草群落〉沙蒿群落,且各群落的RS＋L在1 d中是不稳定的,均表现为不对称的单峰曲线形式;土壤基础呼吸大小排序分别为冰草群落〉甘草群落〉赖草群落〉沙蒿群落,且土壤基础呼吸高的土壤,其土壤养分状况较好。（2）RS相对于气温具有时滞性,4个群落的平均值大小为冰草群落〉赖草群落〉沙蒿群落〉甘草群落。（3）RL平均值大小排序分别为冰草群落〉甘草群落〉赖草群落〉沙蒿群落;对RS＋L的贡献率大小排序为甘草群落〉冰草群落〉沙蒿群落〉赖草群落,表明RL值大的,其对RS＋L的贡献率不一定大,两者之间不存在正相关关系。不同植物群落枯落物对土壤呼吸的贡献与枯落物量、温度因子的相关关系并未表现出一致性,但与15 cm处的地温相关性最高。夏季RL对RS＋L的平均贡献量（以CO2计）在0.05~0.16 g.m-2.h-1之间,平均贡献率在12.88%~35.33%,是大气CO2的一个重要的排放源。

CO2-release rate of soil respiration and litter decomposition in summer of four plant communities in desert steppe

With dynamic closed air chamber method,this paper studied the soil and litter respiration（RS＋L）,soil respiration（RS） in typical desert steppes of the Artemisia desertorum Spreng,Leymus secalinus,Glycyrrhiza uralensis and Agropyron crisatum communities,and then the contribution of the litter decomposition to the total CO2-release（RL） were estimated.The results showed that：（1）The average RS＋L values of four plant communities were different： Agropyron crisatum Leymus secalinus Glycyrrhiza uralensis Artemisia desertorum.And RS＋L of Artemisia desertorum,Leymus secalinus,Glycyrrhiza uralensis and Agropyron crisatum communities was different in one day and all showed an asymmetric daytime pattern.The values of the soil basal respiration were in the following order： Agropyron crisatum Glycyrrhiza uralensis Leymus secalinus Artemisia desertorum.We can see that the higher soil basal respiration,the soil nutrient better.（2）Relatived to temperature,RS had time-lag,and the RS average values of the four plant communities were in the following order： Agropyron crisatum Leymus secalinus Artemisia desertorum Glycyrrhiza uralensis.（3）The RLaverage values of the four plant communities were in the following order： Agropyron crisatum Glycyrrhiza uralensis Artemisia desertorum Leymus secalinus.And the contribution rates of RL to RS＋L were in the following order： Glycyrrhiza uralensis Agropyron crisatum Leymus secalinus Artemisia desertorum.We can see that the RLaverage values and the contribution rates of RL to RS＋L had no positive correlation.The correlationship showed inconsistency between contribution rates and litter quality,temperature,but the contribution rates had better correlation in the soil temperature of 15 cm depth.In summer,the contributions of RLto RS＋Lwere from 0.05 to 0.16 g CO2.m-2.h-1,and the contribution rates were from 12.88% to 35.33%,we thought that the RLwas one of the most important emissions source to the atmospheric CO2.