Benefit Appraisal And Green Patterns Establishment Of Urban Forest In Arid And Semi-Arid Areas

Urban forest is a basic infrastructure to make city sustainable development true. It is imperative for a city in arid and semi-arid areas to reasonably evaluate effects of urban forest and establish green patterns, which are high efficiency, economical to water and stable. 12912 trees belonging to 42 kinds of tree species in 21 yards, 13 streets and 4 squares in Shendong mining area were investigated, and their many kinds of function benefits were measured and appraised including dust removal, carbon dioxide fixation and oxygen release, and water transpiration and heat absorption and air temperature reduction and so on. In addition, tree species selection and green patterns establishment in different function areas were studied using Grey Incidence Analysis and Principal Component Analysis respectively, and many green models were put forward. The main conclusions were as follows: Broad-leaved deciduous trees' leaf areas and function effects including SO2 absorption, carbon dioxide fixation and oxygen release, water transpiration and temperature reduction, heat absorption and energy economy were the greatest, while brushes'were the least totally; for evergreen coniferous tree species, capability of retaining dust was the strongest, and others was between other two tree species. Individually, capabilities of retaining dust of Juniperus rigida , Sabina chinensis , Picea wilsonii, Armeniaca sibirica , Rosa rugosa , Syringa oblata ,Prunus tomentosa were the highest respectively in three kinds of trees mentioned above, while Platycladus orientalis, Prunus davidiana,Tamarix chinensis were the lowest. For CO2 fixation and O2 release, the greatest ones were Sophora japonica Linn.f.pendula, Salix babylonica, Euonymus alatus, Juniperus rigida etc, and the least ones were Acea mono, Forsythia suspensa, Rosa xanthina, Sabina chinensis etc. As to other function effects, Sophora japonica, Salix babylonica, Prunus davidiana, Syringa reticulate (Bl.) Hara var.mandshurica, Picea wilsonii were predominant, and Populus simonii, Sabina chinensis and most of brushes were relatively weak. Comprehensive evaluation results showed that Populus alba var. pyramidalis, Salix babylonica, Sophora japonica, Sabina chinensis, Picea wilsonii, Syringa oblate, Rosa xanthina, Rosa rugosa should be selected in precedence to others in arid city greening, and Sophora japonica Linn.f.pendula, Rhus typhina, Pinus sylvestris var. mongolica etc. were also good green trees. In addition, Populus simonii, Elaeagnus angustifolia, Malus baccata, Xanthoceras sorbifolia, Prunus riloba, Berberis thumbergii etc. may be also selected especially in yards. Tamarix chinensis, Ulmus pumlia were inferior to other trees in yards, and salix matsudana was worse than others in streets and squares. Green amount is a determinant factor to forest ecological effects. Green coverage and green amount per area should be both considered in urban greening. Complicated structure composed of arbors, brushes, vines and grasses was the best green pattern, because of its stabilization, big green amount and obvious effects. In yards, streets, and squares, the green levels were best in Shangwan primary school, the eastern street of Shendong hotel and the western square of Shangwan respectively. In addition, green belt should be widened in street greening so as to improve green effects per green length.