Physiological Characteristics And Ecological Function Of Eight Species Of Landscape Trees

From July to September, eight single planted arbor trees and bushes: Fraxinus americana Linn. , Fraxinus sogdiana Bge. , Quercus robur L. , Ulmus densa Litw. , Ulmus pumila L. var. pendula (Kirchn.) Rend. , Syringa reticulata (Bl.) Hara. var. mandshuica (Maxim.) Hara. , Sorbaria sorbifolia A. Br. and Prunus triloba Lindl. were selected as standard sample trees in the botanical garden of Urumqi. Some physiological indexes such as: net photosynthetic rate, photosynthetic radiation-use efficiency, light saturation point, light compensation point, transpiration rate, water use efficiency and water competitive capacity were determined and analyzed. By understanding physiological characteristics and ecological function of landscape trees and comprehensive evaluating, some scientific grounds were drawn for the choice and arrangement of trees in ecological landscape gardens of arid region city.From the analyses, the conclusions were drawn out that: 1) Net photosynthetic rate, photosynthetic radiation-use efficiency, transpiration rate and water use efficiency were determined and queued up for guiding the choice and arrangement of landscape trees. 2) When the density of Carbon dioxide increase remarkably, the capability of absorption and utilization to Carbon dioxide of Ulmus densa Litw. and Fraxinus sogdiana Bge. is stronger than others'. 3) Light use efficiency to the weak light of landscape trees is bigger than that to the strong light, and LUE reduces gradually with the strengthening intensity of light. 4) Water use efficiency of landscape trees is different, and the difference exists between water competitive capacity and light use efficiency of eight species of landscape trees. 5) Some ecological function: the balance between Carbon dioxide and oxygen,increasing humidity and reducing temperature,green biomass were analyzed.