刈割对华北平原人工草地土壤呼吸速率的影响

根据中国科学院禹城综合试验站牧草生态试验场土壤呼吸测定数据,分析了刈割前后3年生和6年生苜蓿、白三叶及小黑麦4种人工草地土壤呼吸日变化特征及刈割对草地土壤呼吸速率的影响。结果表明:①刈割前不同牧草地的土壤呼吸强度差异明显,依次为3年生苜蓿>6年生苜蓿>白三叶>小黑麦,刈割后不同牧草地的土壤呼吸强度相差不大,土壤呼吸速率在3.0~3.5 μmol CO₂·m^-2·s^-1之间;②刈割前不同牧草地的土壤呼吸日变化不相同,6年生苜蓿与小黑麦草地刈割前土壤呼吸速率由9:00开始逐渐增强,在12:00~16:00之间持续较高,以后逐渐下降,3年生苜蓿与白三叶草草地土壤呼吸速率在9:00~12:00之间逐渐升高,12:00到达峰值,之后逐渐下降;③与刈割前相比,4个处理牧草刈割10 d后其草地的土壤呼吸速率下降了30%~40%;④刈割前后Q₁₀值在1~2.32之间,平均值为1.37,刈割前平均值为1.63,刈割后平均值降为1.10。

Effects of Cutting on Soil Respiration Rate of Cultivated Grassland in North China Plain

Cutting can play a vital role in common management of cultivated grassland.The aim of this study was to clarify the effects of cutting on soil respiration rate of cultivated grassland and the variation of soil respiration before and after cutting.Based on experiment data of soil respiration of cultivated grassland for 4 forages 3-year alfalfa（Medicago sativa L.）,6-year alfalfa,white clover（Trifolium repens L.）,and triticale（Triticosecale Wittmack cv.Triticate-830）] in Yucheng Comprehensive Experimental Station of Chinese Academy of Sciences,daily variations of grassland soil respiration before and after cutting and effects of cutting on grassland soil respirations were determined.The results showed that soil respirations of different grasslands were obviously different before cutting.1) The intensity of grassland soil respirations were 3-year alfalfa>6-year alfalfa>white clover>triticale.However,the intensity of grassland soil respirations was between 3.0-3.5 μmol CO₂·m-2·s-1.2) Before cutting,diurnal variations of soil respirations of different grassland types were also different from each other.Diurnal variations of soil respirations of 6-year alfalfa and triticale were almost the same.Their soil respirations increased gradually from 9:00 and keep relative high values between 12:00 and 16:00,and then decreased gradually.3) Diurnal variations of soil respirations for 3-year alfalfa and white clover were consistent.Their soil respirations increased gradually from 9:00 and got to a climax at 12:00,then decreased gradually after that.Ten days after cutting,grassland soil respirations for all forages decreased by 30%-40% comparing with those before cutting.4) The values of Q₁0 were between 1 and 2.32 before and after cutting and the mean value was 1.37.The mean value of Q₁0 was 1.63 before cutting and was 1.10 after cutting.