白桦和水曲柳树干温度日变化的空间变异及其影响因子  

Spatial variation in diurnal courses of stem temperature of Betula platyphylla and Fraxinus mandshurica and its influencing factors

作　　者：李虞冉 王兴昌[1] 王传宽[1] 刘帆[1] 张全智[1] LI Yu-ran WANG Xing-chang WANG Chuan-kuan LIU Fan ZHANG Quan-zhi(Center for Ecological Research, Northeast Forestry University, Harbin 150040, China）.)

机构地区：[1]东北林业大学生态研究中心,哈尔滨150040

出　　处：《应用生态学报》2017年第10期3197-3207,共11页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(41503071);大学生创新项目(201610225112);教育部长江学者和创新团队发展计划项目(IRT_15R09)资助~~

摘　　要：植物温度是森林生态系统能量平衡和植被呼吸估算的重要参数.采用T型热电偶监测树皮和木材特性各异的2个阔叶树种(白桦和水曲柳)不同深度、高度和方位的树干温度(T_s),探索T_s日变化的空间变异及其影响因素.结果表明:T_s月平均日变化格局与空气温度呈相似的正弦曲线,但T_s变化滞后于空气温度,时滞从树皮表面处的0 h增加到6 cm深度处的4 h.随测定深度的增加和高度的降低,T_s日变化的峰值和日较差均逐渐减小.T_s周向差异不大,休眠季节白天南向、西向T_s日峰值略高.两树种树皮和木材的热学特性(比热容和导热系数)的差异,会通过影响树干表面与外界的热交换和树干内部热扩散而造成T_s径向变化的种间差异.白桦树皮较高的反射率削弱了太阳辐射对T_s的影响.多元逐步回归分析表明,环境因子可以很好地估测T_s日动态(R^2>0.85),影响程度依次为空气温度>水汽压>净辐射>风速.估算生物量热储和树干表面CO2通量时应考虑T_s径向、纵向和种间差异.Plant temperature is an important parameter for estimating energy balance and vegetation respiration of forest ecosystem. To examine spatial variation in diurnal courses of stem temperatures（ Ts） and its influencing factors,we measured the Ts with copper-constantan thermocouples at different depths,heights and azimuths within the stems of two broadleaved tree species with contrasting bark and wood properties,Betula platyphylla and Fraxinus mandshurica. The results showed that the monthly mean diurnal courses of the Ts largely followed that of air temperature with a ‘sinusoidal＇pattern,but the Ts lagged behind the air temperature by 0 h at the stem surface to 4 h at 6 cm depth. The daily maximal values and ranges of the diurnal course of Ts decreased gradually with increasing measuring depth across the stem and decreasing measuring height along the stem. The circumferential variation in Ts was marginal,with slightly higher daily maximal values in the south and west directions during the daytime of the dormant season. Differences in thermal properties（ i. e.,specific heat capacity and thermal conductivity） of both bark and wood tissue between the two species contributed to the inter-specific variations in the radial variation in Ts through influencing the heat exchange between the stem surface and ambient air as well as heat diffusion within the stem.The higher reflectance of the bark of B. platyphylla decreased the influence of solar radiation on Ts.The stepwise regression showed that the diurnal courses of Ts could be well predicted by the environmental factors（ R^2〉 0.85） with an order of influence ranking as air temperature〉 water vapor pressure〉 net radiation 〉wind speed. It is necessary to take the radial,vertical and inter-specific variations in Ts into account when estimating biomass heat storage and stem CO2 efflux.

关 键 词：树干温度 空间变异 日变化 热学特性 

分 类 号：S792.153[农业科学—林木遗传育种] S792.41[农业科学—林学]