Sap Flow Rate and Its Relationship with Environmental Factors of Chinese Fir Plantation in Huitong, Hunan Province Photosynthetic Physiological Characteristics of Planted Allium mongolicum Changes of Gas Exchanges in Leaves of Different Cultivars of Winter Wheat Released in Different Years Photosynthesis-physiological characteristics of Haloxylon ammodendron under different soil moisture grades Response of Linzhi Spruce‘ s Net Photosynthetic Rate to Environmental Factors in Tibet Transpiration of tree species for vegetation restoration in dry-hot river valleys