摘要
通过对西藏高原农田生态系统土壤CO2 排放状况的观测 ,讨论了高原冬小麦、青稞和对照裸地的土壤CO2 排放日变化和季节变化的特征。冬小麦、青稞和对照裸地的CO2 排放的最高点和最低点分别发生于当地时间的 1 3 :0 0～ 1 4:0 0和凌晨 5 :0 0～ 6:0 0左右 ,但在越冬期土壤CO2 排放已很微弱 ,日变化不明显。冬小麦和青稞地的土壤CO2 排放最高值出现在灌浆初期 ,可达到 40g·m- 2 ·d- 1 左右 ;收割后 ,气温和土壤温度也逐渐降低 ,土壤中的微生物和小麦根系的呼吸减弱 ,土壤CO2 排放一般为 2 0g·m- 2 ·d- 1 以下 ;至越冬期 ,土壤CO2 排放降至 2g·m- 2 ·d- 1 左右 ,土壤CO2 排放非常微弱。高原农田土壤CO2 排放与 5cm土壤温度变化相关性最好 ,可用 5cm土壤温度来推算高原冬小麦地的土壤CO2 排放量 ,并由此得到在灌浆期高原冬小麦的根系呼吸所排放的CO2 量占整个土壤的CO2 排放量的 3 4%～ 44% ,平均为 40 %。
Soil respiration of different farmlands were measured and the characteristics of its daily and seasonal variation were identified for the farmlands of winter wheat, Tibet barley and non-crop soil in the Tibetan Plateau. The maximum and minimum soil respiration of winter wheat farmland, Tibet barley farmland and non-cropland occurred at local time 13:00～14:00 and 5:00～6:00 respectively. However, soil respiration in winter was fairly low and daily variation was not apparent. Soil respiration in winter and Tibet barley farmland reached maximum values in the grouting period in a year, accounting for 40 g·m -2·d -1. After harvest, soil respiration, including microorganism and root respiration, gradually reduced to less than 20 g·m -2·d -1 with the air and soil temperature decrease. In winter, soil respiration lessened to some 2 g·m -2·d -1. Soil CO 2 emission was more correlative to 5 cm soil temperature than soil temperature of other layers. Therefore, 5 cm soil temperature can be used for estimating amount of soil respiration. 5 cm soil temperature in growing season and non-growing season were used to separate root respiration from total soil respiration. The ratio of root respiration is 34～44%,averaging 40%.
出处
《资源科学》
CSSCI
CSCD
北大核心
2003年第5期103-107,共5页
Resources Science
基金
国家重点基础研究发展规划项目 (编号 :G19980 40 80 0 )。
关键词
西藏高原
农田
生态系统
土壤呼吸
日变化
季节变化
二氧化碳
Tibetan Plateau
Farmland
Soil respiration
Root respiration
Daily variation
Seasonal variation
