Investigation And Analysis Of Gardening Tree Resources In Northwest China

Virescence, symbolizing the development and civilization of a city, can improve the entironment and habitation of this city. For a perfect landscaping design, well-distributed plants and bountiful species of plant are indispensable. Therefore, a survey of the plant species in the city can provide information for the garden virescence design so as to make it more standardized and more suitable to the local environment thus to reflect the characteristics and bring into play the ecological functions of garden virescence.Based on literature search and the two chief factors, temperature and precipitation, that affect tree growth, the northwest region of China falls into six areas, in each of which one or two cities are selected as the research place. Among all the eleven cities the tree varieties and the relation between city virescence and its entironment have been investigated and studied so as to find out more new resources for garden virescence and to develop and enrich the excellent tree varieties suitable to the city environment in northwest region. The survey, therefore, is of great significance to the construction and improvement of the ecological system in the cities of northwestern regions.The research has the following findings: 1.In the northwestern regions, the tree varieties are rather unevenly distributed among all the cities and the distinction is considerably large. 2.In the same area, the tree varieties in big cities, cities with better climate and long history tend to be much more than those in small cities, cities with poor climate and short history. 3.In the same investigated area, cites with different climate and regional agricultural development differ greatly in the tree varieties, let alone the cities in different investigated area. In the same area, the tree varieties in big cities, well-developed and larger-scale cities and cities with longer history tend to be much more than those in small cities. 4.In conclusion, in the northwestern region, the tree varieties, especially the evergreen varieties, are rather scarce. Among the 11 investigated cities, only in Xi'an, Tian Shui and Han Zhong there is a great proportion of evergreen tree varieties and in most other cities the ratio of evergreen trees to hardwood is one third. Among all the sidewalk trees, the evergreen varieties are in special shortage. No sidewalk in the cities of northwestern region is covered with more than one third of evergreen varieties, which made the cold, desolated winter seem more depressed in this region. 5. Due to the poor climate, underdeveloped economy, little investment in virescence, huge cost in introducing tree varieties and high demands of maintenance and management, in northwestern region more local tree varieties are put intouse than that in southern developed cities. In the course of utilizing the local trees, a large amount of tree varieties haven't been well developed. For example, 50% of the local tree varieties haven't been utilized or seldom used in virescence in Xi'an, and 55% in Han Zhong. As a result, the virescence tree varieties, especially the sidewalk trees, tend to be fewer in northwestern cities in short of virescence resources, which lead to an identical model with minor differences there.Four problems have been found out through my investigation and analysis: 1. There are few virescence tree varieties, esp. the evergreen trees. 2.The utility of the local tree varieties and special varieties need to be expanded. 3. The afforesting acreage is over-stressed while ecological effect is neglected. 4. The city virescence structure is too simple and single-modeled. As for these problems, I proposed four solutions as follows: to establish an integrative management to take advantage of the plants to beautify the setting; to combine regional virescence characteristics with the local conditions; to perfect the law and the regulations concerning virescence and to improve the virescence management ability. Besides, I also come up with 4 principles (priority of integrity and ecology, sustainable development and culture-orientation) to demonstrate available tree varieties for city virescence in northwestern region, which can serve as the guide for virescence there.