通过解析芨芨草(Achnatherum splendens)干草原原生植被生长季中期5、10、20、40、60和80cm 6个土层连续监测的土壤温度资料,探讨其生长季土壤温度和土壤导温率的基本特征.结果表明:芨芨草干草原表层(＜ 20cm)土壤温度日变化明显,遵循正弦波动规律；20 - 40cm为正弦波动和线性振荡的过渡层,40cm以下无显著日变化.土壤温度日变化振幅(A)和相位((φ))随土壤深度(z)增加分别呈现几何级数衰减( A=4.60e-6.74z,R2=0.93)和线性延迟((φ)=6.14z +7.67,R2=0.95)模式；表层土壤温度对脉冲式降水表现为渐变式响应并出现同温层；典型晴天下土壤导温率(κ)随土壤深度增加而指数升高(κ =2×10-7e4.21z,R2=0.92),34.7cm土层的土壤温度日变化与5.0cm反相,而土壤温度日变化恒温层为86.0 -102.0cm土层.%Based on soil surface temperature of six soil layers at depth of 5cm, 10cm, 20cm, 40cm, 60cm and 80cm from June 15 to July 14 in 2010, the variation of soil shallow layer temperature and soil thermal diffusivity was studied. The results showed that there were an obvious sinusoidal diurnal variations of soil temperature from top layers ( <20cm), buffer layer (20 - 40cm) for sinusoidal fluctuation and linear oscillation while undetectable diurnal changes below 40cm soil layers. The amplitude (A) and phase (ψ) of diurnal soil temperature variations declined exponentially (A=4. 60e-6.74z,R2=0.93) and linearly (ψ =6. 14z +7.67,R2=0. 95) with the soil depth (z) increased, respectively. The response to pulse precipitation of soil temperature at top layers changed gradually, and resulted in the same thermal soil layers. Soil thermal diffusivity (K) was enhanced exponentially (K =2 × 10-7e4.21z,R2=0. 92) with soil depth enhancement. There were totally opposite diurnal fluctuations between 34. 7cm and 5. Ocm. The depth of diurnal constant temperature strata was about 86. 0 -102. 0cm.
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