关键词: 日动态, 环境因子, 短期测定, 土壤呼吸速率

Abstract: Soil respiration is very important for global carbon budget, while the measurements once a day may cause biases in results. For detecting the deviations, and determining the best time for measuring soil respiration rates, simultaneous determinations of the diurnal dynamics of soil respiration, soil temperature and air temperature of four vegetation types (forest, shrub, grassland, meadow) and 13 community composition types in the Saihanba Forestry Center, Hebei Province, north China were made from June to August, 2011. It was found that soil respiration rates deviate -26%~68% from the average when measured at different times. Soil respiration rate was less affected by time of day in the forest, while 7:30?10:30 and 17:00?19:00 may be the best time for measurements in grassland and meadow (average deviation < 10%). The daily variations in soil respiration rates were closely correlated to that of soil and air temperature. This study suggests that soil respiration rates are affected by daily changes that cannot be ignored.

Key words: daily change, environmental factor, short-time measurement, soil respiration rates