Study On Photosynthetic And Transpiration Of Dominant Tree Species In Beijing Mountainous Area

This article mainly researches Photosynthetic and Transpiration of Dominant Tree Species in Miyun reservoir watershed in Mountain Area of Northern China .Reveal characteristics and rules of water consumption of different species. On the basic of the analytical results, combine drought-resistant afforestation technology; find the low consumption tree species and optimum planting density.Contraposing the existing vegetation of Miyun reservoir watershed, choosing 22 kinds of shrubs and two pieces of typical forest stand as research object, obtain following conclusion by pot experiment and experiment of typical forest stand, field and experimental research, applying statistical method to analyze photosynthetic and transpiration. The main conclusion is as follows:Because of biological characteristics of different tree species, form different Ecological Adaptability. At water enough condition, 22 tree species of the young plant used in the experiment whose tendency of transpiration rate, photosynthetic rate and the diurnal changes of water use efficiency are similar. The transpiration rate of arbor trees is higher than Coniferous Trees', but in the average efficiency of using water, Coniferous Trees is greatly higher than arbor trees'. The transpiration rate of positive shrub species is greatly higher than negative shrubs species', but in the average efficiency of using water, negative shrubs species is greatly higher than Coniferous Trees'.The water consumption of tree increased with increasing stand density,thus,the soil moisture decreased correspondingly.The bare soil had strong evaporation and its watercontent was lower than woodland.Therefore,the reasonable spatial structure and stand density inforestation would be beneficial to increase and maintain soil moisture.