Abstract: With the QuickBird RS images of the Three Circles of Xi’an City as the basis and under the support of GIS, a 20-m unit was taken as the appropriate grain size based on the sensitivity analysis of different grain size landscape pattern indices, and the present landscape pattern of the city was analyzed. The results indicated that in this city, residential and industrial areas were concentrated and artificial landscapes were congregated, which affected the natural ecological processes. Greenbelts and water bodies were highly fragmented, and distributed separately. The landscape structure within the 1st circle was unreasonable, different type landscapes between the 1st and 2nd circles had no uniform distribution, and the potential economic and ecological effects of land use between the 2nd and 3rd circle were quite high. It was suggested that the urban space structure and distribution of Xi’an City should be adjusted, and the continuity of landscape ecological processes and patterns should be maintained from the aspects of green belt landscape construction and water system protection.

Key words: CO₂ concentration, Rhizosphere soil, Bacteria, Fungi, Actinomyces