Seasonal and diurnal variation of energy budget components in coniferous forests
Seasonal and diurnal variation of energy budget components in coniferous forests
复制标题
针叶林能量预算成分的季节和日变化
DOI：
10.1016/0022-1694(85)90042-3
复制
发表时间：
1985
影响因子：
6.4
通讯作者：
A. Lindroth
中科院分区：
文献类型：
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作者：
A. Lindroth
这项研究是70年代S在瑞典进行的大型多学科生态系统调查的一部分。非生物研究的主要目的之一是加深我们对控制北方针叶林局部和小气候的物理过程的理解。作为这项研究的一部分，对瑞典中部一片稀疏松林的能量收支进行了深入的研究。对1977-1978年间波文比的分析表明，用于感热和潜热通量的净辐射(Rn)的比例在整个季节并不是恒定的。这一比率从5月份的约40%上升到8月份和9月份的60%左右。5月平均白天干冠层潜热通量约为135W m−2，7、8月份增加到15 0~160W m−2，9月份下降到10 0W m−2。感热通量由5月的190W m−2下降到9月的55W m−2。白天平均储能速率在5、9月份最大，约为23W m−2，7月份最小，约为12W m−2。中午的波文比由5月份的2左右下降到8、9月份的0.5~1。在为期6天的时间里，对地面植被和整个森林的蒸散量进行了同步测量。白天平均，约59%的净辐射用于潜热通量，32%用于感热通量，9%用于储存。只有13%的潜热通量来自地面植被，而50%以上的感热通量来自地面。四种欧洲针叶林的比较表明，白天的平均潜热通量变化较小。平均潜热通量速率为135±27W·m-−~2，林分密度与潜热通量速率之间不存在相关关系。
This study was part of the large multidisciplinary ecosystem investigations undertaken in Sweden during the 70's. One of the main aims of the abiotic research was to deepen our understanding of the physical processes governing the local-and microclimate of northern coniferous forests. As part of this, the energy budget of a sparse pine forest in central Sweden was intensively studied. Analysis of Bowen ratio measurements during 1977 and 1978 showed that the fraction of net radiation (R n) utilized for sensible and latent heat (LE) fluxes was not constant over the season. The ratio LE R n increased from about 40% in May to about 60% in August and September. The mean daytime latent heat flux from a dry canopy was about 135 W m− 2 in May, increasing to 150–160 W m− 2 in July and August and then decreasing to 100 W m− 2 in September. The sensible heat flux decreased from about 190 W m− 2 in May to 55 W m− 2 in September. The mean daytime energy storage rate was largest in May and September with about 23 W m− 2 and smallest in July with 12 W m− 2. The Bowen ratio at noon decreased from about 2 in May to 0.5-1 in August and September. During a period of six days, simultaneous measurements of evapotranspiration from the ground vegetation and the whole forest were made. Averaged over the daytime period, about 59% of the net radiation was used for latent heat flux, 32% for sensible heat flux and 9% for storage. Only 13% of the latent heat flux came from the ground vegetation while more than 50% of the sensible heat flux originated from the ground. Comparison between four European coniferous forests showed that the mean daytime latent heat flux varied relatively little. The mean rate was 135±27 W m− 2 and there was no correlation between density of forest and rate of latent heat flux.