The habitat quality and connectivity structure of urban small and medium-sized green space play an important role in promoting urban biodiversity. Under the influence of community life circle services, the urban green space construction in China has formed a typical and repetitive green space pattern. Exploring the minimum quadrat of green space composition and its habitat elements and morphological structure is an important way to improve the urban ecological quality and green space planning and design. This research, based on the basic achievements of urban site habitat construction and ground cover plant community design in northwest China, takes the green space in the old and new urban areas of Xi’an City as the objects. It puts forward the basic scale quadrat of “2 km×2 km” urban block green space habitat network by using the research paths of review, geographic information interpretation-field surveys and cluster analysis. It has found four typical patterns, which are single-core radiation, multi-core dispersion, corridor crossing and scattered distribution. It also analyzes the coupling relationship between the form, elements and spatial pattern of the quadrat, and explores the ways to improve the construction of green spatial habitat network in the quadrat system.

In order to further tap the ecological potential of urban trees, improve the diversity of tree species in urban environment, and promote the sustainable development of urban trees, this paper further analyzes the structure, diversity and spatial distribution law of the prominent tree species in Hefei city on the basis of on–the–spot identification of the prominent trees distributed in the main city. The results show that: 1) 528 significant trees are identified in the three districts, belonging to 40 species, 36 genera and 27 families, with 23 trees evaluated by qualitative index and 505 trees by quantitative index. In quantity distribution, the number of significant trees in the three districts is ranked as Yaohai District> firstringroad City> Government Affairs District. The top four tree species in relative abundance are Platanus acerifolia, Cinnamomum camphora, Ginkgo biloba and Cedar. 2) In terms of the tree age structure, most trees are 20~40 years old, and only 22 trees are over 100 years old; the ratio of evergreen to deciduous tree species is 1: 3, and the ratio of plant to tree is about 7: 18; there are 23 native tree species accounting for 57.50%, but only 171 trees. 3) In terms of area distribution, the average tree height and crown area in Yaohai District are the largest, the average DBH, Shannon–Wiener index and Simpson index in the first–ring city area are the highest, and the species evenness index in Government District is the highest. 4) In terms of site types, most significant trees are distributed in urban streets, residential areas and parks, and only 11.74% of them are distributed in government organizations, schools, public facilities, scenic spots and religious land.

This paper explores the relationship between the spatial scale and biodiversity protection level and thinks that under the specifi c urban-region scale, landscape diversity is the key level to the macroscopic protection of biodiversity. Based on the systematicness and the otherness of urban–regional environment and the biologic fl ow and process, the protection pattern of biodiversity within urban–regional scale should be established. The author holds that seeking the “optimal landscape pattern”is one of the core missions of biodiversity protection planning. Based on that, the paper summarizes the two types of city space and their biodiversity planning and design in two ways: first, the”Urban-rural landscape pattern optimization approach”specific to the space of city matrix, which includes “agglomeration segregation”,”landscape”, “green infrastructure”, three models and five pattern optimization strategies; second,  the “Nature reserve approach” specific to the space of natural matrix, which includes”reserve circle”and”protected area network”two modes and six reserve design principles.

In Japan, the environmental degradation in the urban and urban fringe area advanced from rapid economic growth to begin at the mid-1950s. The environmental aggravation such as large-scale development of the city with little consideration of environment, air pollution and the noise and so on had a big influence at the biological diversity. The habitation space of the creature is decreased or disappeared, and biological diversity suddenly is decreased. This tendency continued after stability of the economic growth of the mid-1970s. The environment of the urban area was not desirable space for the creatures. In addition, it decreased the ecosystem service. However, this problem lies in administration and private consciousness, and improves the consciousness of inhabitants and the reduction of the pollution, as well as the maintenance and creation of the urban greening advanced, and the environment of the urban area was improved