合肥市区城市森林景观格局分析

运用3S技术在分析合肥景观特点的基础上，研究了合肥市区17．6km^2范围内的城市森林景观特点及与其它景观单元间关系。结果表明，主要景观要素分为建筑与硬质铺装表面、城市森林斑块、一般绿地、道路、水面五大类景观背景为建筑及铺装表面，占总面积的73．13％；道路为典型的廊道景观，约占6．89％；研究区城市森林斑块共408块，计161．16hm^2，占总面积的9．8％，平均面积0．396hm^2、最大面积12hm^2，斑块形状复杂、近圆度小，其中48％的班块属于面积<500m^2的小班块，>1hm^2的城市森林班块只占8．6％；水面斑块147块，计149．93hm^2，占总面积的8．54％，平均面积1．02hm^2，最大面积16hm^2；一般绿地斑块255块，计39．74hm^2，占2．26％，最大面积3．86hm^2，平均面积0．1558hm^2．Shanlnon—Weiner景观多样性指数和均匀度均偏低，分别为0．9284和0．5768。另外，城市森林与一般绿地两类景观要素的总优势度达0．39，由于这两类景观斑块的尺度变化范围大，比较破碎，小尺度的斑块所占比例高，又主要集中在西区，分布不均匀，故对环境的影响作用受到限制，文中引用自然森林的内部生境概念，确定合肥城市森林斑块出现内部环境的l临界面积为9800m^2，研究区拥有城市森林的内部生境总面积为31．69hm^2，仅为城市森林面积的19．7％，不利于对物种提供更多的生境，提出应用内部生境的大小来划分城市森林斑块，建立城市森林小班块—中斑块—大斑块—特大斑块的尺度等级体系，据此提出，研究区各尺度的城市森林斑块面积比为2：2：2：3。同时提出合肥东北部应增加城市森林面积，尽可能建设1．5～3．0hm^2的片状城市森林。

Analysis of urban forest landscape pattern in Hefei

Based on the theory and methodology of landscape ecology, the landscape pattern of the study area (17.6 km2) in the downtown of Hefei was analyzed by using the techniques of RS, GPS and GIS. The object was to provide a comprehensive method to study urban forest structure and its function in environmental improvement. The results showed that there were 5 major landscape elements, i.e., building and hard pavement surface, water, road, urban forest, and general green land in the area. The landscape matrix was building and pavement surface, occupied 73.13% of total land. Road was the typical corridor element in the city and occupied 6.89%. Green land occupied 11.44%, in which, urban forest patch occupied 9.18%. There were 408 urban forest patches, with an area of 161.16 hm2. The average area of the patch was 0.396 hm2, and the maximum area was 12 hm2. 48% of urban forest patch was identified as small scale patches with < 500 m2 of area, and only 8.6% of them was larger than 1 hm2. The number of general green land patch was 255, with an area of 39.74 hm2, which accounted for 2.26% of land area, and its average and maximum area was 0.1558 hm2 and 3.86 hm2, respectively. There were 147 water patches, with an area of 149.93 hm2, and occupied 8.54% of land, and the average and maximum area of the patch was 1.02 hm2 and 16 hm2, respectively. In the study area, both of the Shannon-Weiner landscape diversity index and evenness were low, only 0.928 and 0.576, respectively. In addition, the dominance of urban forest patch and general green land was 0.39 showing that the two landscape elements had a certain influence on the environment of the study area. The concept of interior habitat for forest was introduced in this paper, which was employed to make a scale class system of urban forest patch. The threshold area with interior habitat for urban forest patch was 9800 m2, and there was 31.69 hm2 of interior habitat of urban forest in total, which occupied 19.7% of the total area of urban forest patch. This situation was not favorable for providing more habitats to support species diversity. It's suggested that the concept of interior habitat could be employed to identify urban forest patch, and a scale system of small scale patch of urban forest-middle patch-large patch-extra large patch was build in the paper. Based on this system, the ratio of different scales of urban forest patch in the study area should be 2:2:2:3. The authors also suggested that larger pieces (1.5-3.0 hm2) of urban forest patch should be built, and more urban forests should be established in the northeastern part of the city in the future.