Abstract: Both diurnal and seasonal dynamics of soil respiration in three-year old alfalfa(Medicago sativa L.)filed were measured using LI-8100 Automated Soil CO₂ Flux System.The relationships between soil respiration,soil moisture and solar radiation were analyzed.Results indicated that the diurnal dynamics of soil respiration presented a single peaked curve.The lowest value was 3.102,2.071,4.655,4.52,3.355 μmol·m^-2·s^-1 appearing at 8:00-9:00 or 18:00-19:00 for each observed day,respectively.And the highest value was 4.934,3.034,6.948,5.682,4.823 μmol·m^-2·s^-1 appearing at 13:00-16:00.Seasonal dynamic of soil respiration showed an irregular single peak with the minimum 2.48 μmol·m^-2·s^-1 value at June and the maximum 5.79 μmol·m^-2·s^-1 value at July.The diurnal dynamics of soil respiration had a significant correlation to the soil temperatures of 5cm depth and R2 values were 0.2722～0.8214(P<0.05).There is no significant correlation between the diurnal dynamics of soil respiration and the soil temperature of 20 cm depth(P>0.05).The seasonal dynamics of soil respiration had no significant correlation to solar radiation and the soil temperature at 5,10 and 20 cm depth(P>0.05).However,there was a significant correlation to the soil moisture at 5,10 and 20 cm depth(P<0.01).

Key words: Alfalfa fields, Soil respiration rate, Environment response

摘要： 采用LI-8100对河北沽源牧场地区3年生苜蓿(Medicago sativa L.)草地生长季土壤呼吸速率日动态以及季动态进行测定,分析了土壤呼吸速率与土壤温度、土壤湿度和大气辐射的相关性。结果表明:苜蓿草地的土壤呼吸日动态呈单峰曲线,各观测日的最小值分别为3.102,2.071,4.655,4.52,3.355μmol·m^-2·s^-1,出现在每天8:00-9:00和18:00-19:00之间,相对应的最大值分别是4.934,3.034,6.948,5.682,4.823μmol·m^-2·s^-1,出现在13:00-16:00之间。土壤呼吸速率日动态与5 cm土壤温度的相关性最大,R2的值为0.2722~0.8214(P<0.05),与10 cm土壤温度有一定的相关性,与20 cm土壤温度相关性不大。土壤呼吸季动态呈不规则单峰曲线,最小值是2.48μmol·m^-2·s^-1,出现在6月26日,最大值是5.79μmol·m^-2·s^-1,出现在7月24日。土壤呼吸季动态与5,10,20 cm深度的土壤温度均无相关性,与5,10,20 cm深度土壤湿度均有极相关关系(P<0.01),与太阳辐射无相关性。

关键词: 苜蓿草地, 土壤呼吸速率, 环境响应