30 3 Vol.30 No TROPICAL GEOGRAPHY May 2010

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1 30 3 Vol.30o TROPICAL GEOGRAPHY May2010 % %

2 Tab.1 Classificaon system and interpret symbol of coastal wetland in the Pearl River Estuary : : % X Y t t C X i1 i1 C i 1 C i 1 C i Yi

3 Tab.2 Comparison of area and proporon of wetland in the three periods % % % Fig1 Studied area and coastal segments division (a) (b) (c) km Fig2 Wetland landscape distribuon in 1986a1995band 2005cof the Pearl River Estuary

4 % % Tab.3 Landscape index Tab.4 Area changes of wetland in the five segments

5 % % a. 整体 b. 鸡啼门 前山水道 c. 前山水道 横门 d. 横门 蕉门 e. 虎门 狮子洋 f. 交椅湾 深圳 Fig.3 Spaal changes of wetland landscape centroids of enre and five divided segments

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7 Study on Ecological Stress in the Urban Fringe of Guangzhou City Based on Landscape PatternA Case Study of Panyu District ZHAG Huixia 1 LOU Quansheng 2 LI Yan 1 1School of Resource and Environment, Guangdong University of Business Studies, Guangzhou , China; 2South China Sea Marine Engineering and Environment Instute, SOA, Guangzhou , China Abstract: With RS, GIS and stascal method, an ecological stress index model is established by selecng landscape fragmentaon index, patch cohesion index, fractal dimension index and land use sensivity index. Spaal disparity of the ecological stress with urbanizaon gradient at the urban fringe of Panyu district in Guangzhou City is studied. The results show that: the average patch area increases from suburb to exurb. The rao of arficial landscape decreases and that of natural landscape increases in the direcon of urban expasion. The landscape index of different landuse type vary with disturbance intensity of human acvity in three gradients. The ecological stress presents a patterns a pattern of decrease from north to south. Its distribuon has close correlaonship to the regional land-use mode and intensity. Human disturbance plays a dominant role in diffusion of landscape ecological stress. Key words: landscape pattern; urban fringe; ecological stress; Panyu District On Changes in Landscape Pattern of Coastal Wetland around the Pearl River Estuary in Past Two Decades GAO Yi 1,2,3,4,SU Fenzhen 2,SU Xiaoyu 2,XUE Zhenshan 2 (1.Yantai Instute of Coastal Zone Research for Sustainable Development,CAS,Yantai ,China;2.Instute of Geographic Sciences and atural Resources Research,CAS,Beijing ,China;3.South China Sea Instute of Oceanology,CAS,Guangzhou ,China; 4.Graduate School of Chinese Academy of Sciences,Beijing 10039,China) Abstract:Coastal wetland data in the years of 1986, 1995 and 2005 of the Pearl River Estuary was extracted from the mac maps and remote sensing images respecvely by using GIS and RS. Some indexes of landscape pattern, such as landscape diversity index, landscape contagion index and landscape fractal dimensions were chosen to describe the spaal pattern of the Pearl River Estuary coastal zone in the past two decades at both landscape and patch type level. The result shows that: (1) Among all the wetland types, the area of shallow waters accounted for the largest proporon, that was % in 1986, % in 1995 and % in The area of aquaculture water landscape increased the most, while paddy fields decreased the most. (2) Affected by human factors, the total area of wetland in the Pearl River Estuary coastal zone connued to decline. From 1986 to 1995, it decreased hm², and from 1995 to 2005 decreased hm², accounng for 5.3 % and 14.2 % of the total studied area respecvely. (3) The changes of wetland landscape were of temporal heterogeneity, and the distribuon of that had significant spaal heterogeneity. The landscape contagion index of each wetland type decreased to a great extent, while the landscape fractal dimensions increased disncvely during the two periods. In terms of landscape diversity index it showed a decrease after an increase. (4) The centroid of the wetland in the Pearl River Estuary coastal zone moved northwards from 1986 to 1995 by a linear distance of 0.4 km, and moved southeastwards from 1995 to 2005 by 6.1 km. By comparison between the wetland area decreasing speed and the centroid displacing speed, it can be concluded that the degradaon of the wetlands is accelerated. Key words: the Pearl River Estuary; coastal wetland; landscape index; spaal change