| Urban forest system which is mainly founded by woody plant communities is of consequence to maintain and improve the urban environment, to improve the person-reside environmental quality and to construct an ecological city and good for inhabitation. Based on the landscape ecology theories and methods, the landscape structure of urban forest system was analysed and evaluated. It provides scientific basis for spatial distribution pattern of urban forest land and landscape ecological programming.In this paper, the study object is forest system in Chongqing metropolitan regions, using the theories and methods of landscape ecology. A map based on RS technique, GIS technique and investigation on the spot with a scale of 1:500,000 were used for analyzing forest horizontal pattern in Chongqing metropolitan regions. To get the optimum way of landscape pattern is from landscape indexes analyzing on a map with a scale of 1:100,000. The study results offer basic data and academic gist for the forest system constructing and programming in central downtown part.Got out following conclusions:1) In Chongqing metropolitan regions, Jin-yun Mountain, Zhong-liang Mountain, Long-wang Dong Mountain, Tong-luo Mountain, Ming-yue Mountain and Tao-zi Dang Mountain are all Northeast Southwest tending towards, embodied the characteristic of Chongqing paralleled ridge-valley. The cover rate of natural forest is higher than background area in the mountains. There are 5 forest land types: evergreen broad-leaved forests, evergreen coniferous forest, evergreen and deciduous broad-leaved forest, evergreen broad-leaved and coniferous forest and bamboo grove. Forest total area is 104,017hm~2 and 19% of this region, which is concentrated in Jin-yun Mountain, Zhong-liang Mountain, Tong-luo Mountain and Ming-yue Mountain, and the preponderant type is evergreen coniferous forest. The 6 mountains are green strips and the average area is 23 881hm~2. With low boundary density, large shape index numbers, large in ratio of long with broad, it is good for maintaining and improving the urban environmental quality.2) Total area of forest land in central downtown part is 5385hm~2 and the cover rate is 10.4%. The natural forest which is holding up 8.5% of the study region area is 4402hm~2. It is concentrated in Zhongliang Mountain and Tongluo Mountain and there're 4 plant types: evergreen broad-leaf forest, evergreen coniferous forest, evergreen and deciduous broad-leaved forest, evergreen broad-leaf and coniferous forest. The preponderant type is evergreen coniferous forest.According to character of community type and extensity pattern, low boundary density, large shape index numbers, high fragmented index and biggish variant coefficient are hold in paths of different forests.The eastern Zhong-liang Mountain and western Tong-luo Mountain which contacted with city hard core area are 2 green ways, founded by forest plants. The character of 2 green corridors is large in area, biggish in boundary density, large in ratio of long with broad and much unequal in form. 3) There are no natural forests in the city hard core area and 1.9% of the central city part 983.56hm~2 is forest land in existence. Based on the urban greenland system types, the forest in the city hard core area is partitioned to public park forest, accessory forest and others. The area variant coefficient of forest in city hard core is smaller than mountain forest path obviously. The boundary density of forest land in city hard core area is big and the integrity of patch distribution pattern is poor. The path shape index and fractal dimension of forest path in city hard core area are large and the boundary is more complex than mountain forest path. The absolute value of fragmented index is lower than normal, but higher than mountain absolute value of fragmented index in this region. The park forest's separation index is largest in 3 types. The forest landscape diversity of the park forest, which has lowest diversity, is lower than mountain forest. Forest land in city hard core area has larger equality index than mountain forest and which has very low connectivity index.4)The suitability analysis of the forest land system in central downtown part showed that, the suitable land for forest construction mainly concentrated in the traversing farmland or the farming and forestry mixing zone around the city branch road along the route, and then concentrated in the riparian belt-shaped distribution strip; There was nearly no other land fit for forest land in the entire of Yu-Zhong district and the core area of Sha-Pingba district, there was still a good deal of farmland could be possibly designed for forest land construction in Yu-Bei district and Jiang-Bei district, and there was few dispersed cropland fit for afforestation in the Jiu-Longpo,Nan-Ping and Ba-Nan district.5)In the forest land system landscape structure optimization content in central downtown of Chongqing, the paper studied the combination of ring, line, wedge, point in the forest land system, and proposed strategy for the ring-like forest land, the corridor forest land, the wedge-shaped forest land and the punctual forest land.The ring-like forest land is composed by the Zhong-liang Mountain, Tong-luo Mountain and the north and south forest belt along the both sides of inner rim highway, circles the hard core area of urban district. Combined with the suitability analysis and present situation, forest belt width partition established segmently, variated between 100m-1000m.The corridor forest land construction mainly focused on the both side of the Changjiang River, the Jialing River and both side of inner rim highway near the Zhong-liang Mountain and Tong-Luo Mountain, also considered the nearby main roads and the rill river peripheral. The width on each side of the inner rim highway is from 40m to 200m, other main road side width from 30m to 60m. For the Changjiang River, Jialing River riparian the tight land sector, the forest belt width should no less than 30m. In addition, the width of forest belt in some other important rivers between 20m and 30m.The paper marked out the central mountain ridge gage into the wedge-shaped forest land. Combined with the existing four models wedge-shaped forest land patches, planned several small patches which were 2hm~2-20hm~2 to increased the Connectivity of the entire ridge line forest belt. The planned wedge-shaped forest land's acreage was approximately 128hm~2.In this paper, 99 punctuate forest lands were planned, total area approximately 1864.8hm~2. Among these, four large forest land patches which are above the 100hm~2 were planned to transform and built in Yu-Bei district, Jiang-Bei district, Nan-An district and Da-Dukou district, the middle and small scale forest land patches were equably distributed in urban district, Through organic synthesized among the large, middle and small patches, connected with the main forest land corridor, finally formed the green network system.After planning, the forest land total area was 11,680.9hm~2 and the rate was 22.6%. The forest land patch fragmented index in urban district hard core area was reduced greatly, the degree of separation was enhanced, and the connection index was also promoted. As a whole, the stability of forest landscape gets exaltation.
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