落叶松人工林土壤热传导季节变化及其与环境因子的关系

以2003—2005年落叶松人工林土壤热状况的实际监测数据为基础，研究了其土壤热传导特性及其与环境因子的关系.结果表明：落叶松人工林不同年份、不同地点土壤热通量的季节变化十分明显，4—8月为正值，9月至次年3月的绝大部分时间为负值，其年收支基本处于平衡状态.土壤热通量和土壤热导率（k）受净辐射影响显著，并存在时间延迟效应，冬季为4～5 h，夏季为2～3 h.基于实测的土壤热通量和土壤温度差计算得到的k值早春季节显著高于其他季节（P<0.05），而其他月份不存在显著差异(P>0.05).使用我国大多数气象观测站积累的土壤温差数据和 k值进行土壤热通量季节变化估计时，早春季节（3—5月）可能会产生较大的误差.

Seasonal variation of soil heat conduction in a larch plantation and its relations to environmental factors.

Based on a 3-year (2003-2005) observation of soil heat flux (SHF) in a larch (Larix gmelinii) plantation, the characteristics of soil heat conduction in the plantation and their relationships with environment factors were analyzed. The results showed that there was an obvious seasonal variation of SHF in different years and sampling sites. The SHF was positive from April to August and mostly negative from September to next March, with an almost balance between heat income and outcome at annual scale. Solar net radiation had significant effects on the SHF and soil heat conductance (k), and an obvious time-lag effect was found, with 4-5 hours’ time-lag in winter and 2-3 hours’ time-lag in summer. Based on the real-time measurement of SHF and soil temperature difference at the study sites, the k value was significantly higher in early spring (P<0.05), but no significant difference was observed in other seasons (P>0.05). Therefore, when we use the observation data of soil temperature from weather stations to estimate soil heat flux, the k value in spring (from March to May) could induce a bias estimation.