油松枝干水容特征及其对蒸腾耗水的影响

Water capacity of branches and stems of Pinus tabulaeformis and its impact on transpiring water consumption.

该文通过对油松枝条和茎干组织水容特征研究,旨在进一步阐明树体水容对蒸腾耗水的影响,为油松山地造林和城市绿化水分管理提供理论指导.研究结果表明:①枝条水容日变化表现为先减低后回升,枝条水容与水势呈二项函数关系.②在季节变化上,水容受土壤和环境水分的影响,6月份枝条水容值比9月份大.③在空间上,不同冠层和不同方位的枝条水容有差异,其中,下部枝条水容值比上部的稍大,东南部的水容值比西北部的稍大;不同树干高度液流通量的变化受边材面积大小的影响,自基部沿树干高度递减;在白天树干茎段累计水容下位要比上位大,但树干水容的亏缺可以在晚间得到一定程度的补充.④在对蒸腾耗水的调节上,树体上位组织的储存水首先被耗散,依次拉动下位,直至根系主动吸水.

The characteristics of water capacity of branches and stems of Pinus tabulaeformis were studied in this paper to further illustrate the laws and controlling mechanisms in water consumption of forest tree species, and then provide a theoretical guidance for water management and the afforestation of P. tabulaeformis. Results showed that the diurnal fluctuation of branch relative water capacity of P. tabulaeformis decreased first and rised then. The branch water capacity and water potential assumed inverse function relations. The seasonal variations of relative water capacity of branches were influenced by the factors of soil and environment. And the size of water capacity was larger in June than that in September. Spatial variations of the relative water capacity of branches at different parts and directions had some differences, /e the upper crown＇ s must be slightly larger than that of the below, and the southeastern must be slightly larger than that of the northeastern. Sap flow flux was influenced by sapwood area size, and decreased progressively from the base along the trunk to the top of tree. Deficit of water capacity of the top stem sections may receive supplement at night. As to its impact on the transpiring water consumption, the top tree body＇s storing water is dissipated first, then draws the lower position in turn, until the root system absorbs water actively.