Physiological Characteristics Comparison of Mixed and Pure Forest of Platycladus orientalis in Shandong Limestone Mountain

[Objective] To analyze the effect of different afforest model to barren hill on physiological characteristics of Platycladus orientalis,provide the theoretical basis for afforestation.[Method] Photosynthesis and transpiration were ascertained by measuring from 8 am to 6 pm every two hours in April 26 and 27,2004,the photosynthesis characteristics,transpiration characteristics and moisture content characteristics in leaves of Platycladus orientalis in mixed Platycladus orientalis-Pinus tabulaeformis forest and in pure Platycladus orientalis forest were investigated.[Result] The diurnal changes of net photosynthesis rate and transpiration rate of Platycladus orientalis in mixed Platycladus orientalis-Pinus tabulaeformis forest were different from pure Platycladus orientalis forest,as well as the relativity between photosynthesis rate of Platycladus orientalis in mixed forest and light intensity,air temperature,air humidity,the temperature of leave chamber and CO2 content in air.The mean photosynthesis rate of pure forest was 54.1% of the one of the mixed forest.The moisture content in leaves of two type of forest had not marked difference.Relative moisture content in the leaves of mixed forest was higher than that of pure forest,while its natural water saturation deficiency was lower than that of pure forest.[Conclusion] Under a good forest microclimate condition or with much soil moisture,the state of water balance for mixed forest was better than that of pure forest.