Progress in Physical Geography

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Changes of urban wetlands in Wuhan, China, from 1987 to 2005 Kai Xu, Chunfang Kong, Gang Liu, Chonglong Wu, Hongbin Deng, Yi Zhang and Qianlai Zhuang Progress in Physical Geography 2010; 34; 207 DOI: 10.1177/0309133309360626

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Progress in Physical Geography 34(2) 207–220 ª The Author(s) 2010 Changes of urban wetlands in Reprints and permission: sagepub.co.uk/journalsPermissions.nav Wuhan, China, from 1987 to 2005 DOI: 10.1177/0309133309360626 ppg.sagepub.com

Kai Xu China University of Geosciences, China; Beijing Normal University, China Chunfang Kong China University of Geosciences, China Gang Liu China University of Geosciences, China Chonglong Wu China University of Geosciences, China Hongbin Deng China University of Geosciences, China Yi Zhang Central China Normal University, China Qianlai Zhuang Purdue University, USA

Abstract Urban wetlands play a significant role in the sustainable development of the urban eco-environment. However, accelerated urbanization has caused rapid changes in urban wetland landscape patterns, which may seriously affect their functions. Based on land-use maps, TM images, and field data from the Wuhan wetlands, the spatiotemporal evolution and wetland landscape pattern were quantitatively analyzed, with reference to landscape ecology indices of diversity, fragmentation, dominance, shape, and dimension. The results showed that: (1) the natural wetland area decreased: lake wetlands and marsh wetlands decreased by 18.71% and 50.3% from 1987 to 2005, respectively; (2) artificial wetland area increased by 47.75% in Wuhan over the same period; (3) the lake wetland area of Wuhan declined due to the conversion of large lakes to smaller ones; (4) the value of the diversity index (H), evenness index (E), and fragmentation index (F) decreased, while the value of the dominance index (D) increased from 1987 to 2005; (5) the landscape shape index (LSI) and fractal dimension (FD) of the river wetlands, lake wetlands, bottomland wetlands, and marsh wetlands decreased, while the LSI and FD of the reservoir and pond wetlands increased from 1987 to 2005; and (6) natural, societal, and economic, as well as human, activities are major factors for the structural changes in the Wuhan wetland landscape, as revealed by canonical correlation analysis. Results suggest that the ecological environment of urban wetlands should be protected to maximize the services of urban wetland ecosystems in Wuhan, China.

Corresponding author: Qianlai Zhuang, Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907, USA Email: [email protected]

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Keywords driving force, ecological method, Geographic Information System (GIS), landscape pattern, TM imageries, Wuhan

I Introduction environment assessment (White et al., 1997; Urban wetlands mainly refer to those wetlands Joyal et al., 2001). In recent years, the dynamics lying within the boundaries of cities, towns, and of wetland landscape patterns in China have non-agricultural areas adjacent to the urban been investigated using different methods in region, including those wetlands located within different locations, including land-use changes the region of satellite towns around centre in the Dongting Lake wetland using landscape cities. Wetlands form an important ecological indices (Zhao et al., 2002), wetland patterns in infrastructure of urban areas and provide varied Sanjiang Plain (Wang et al., 2003), and the ecological and social services in urban eco- characteristics and driving forces of wetland environments. It is now widely recognized that changes in the middle-lower reaches of the the sustainability of urban development depends Taoer River (Guo et al., 2004) using landscape on the provision and maintenance of forward- ecological methods. All these studies contrib- looking municipal and ecological infrastructures. ute to the development of wetland science and Therefore, it is important to investigate the landscape ecology. However, research on the dynamic evolution of the urban wetland land- dynamic changes in the urban wetland landscape pattern and their driving mechanisms scape pattern and the driving mechanisms is (Weber and Puissant, 2003; Xu et al., 2009) in still limited, particularly in a specific region rapidly urbanizing environments. with some unique wetland characteristics, such Landscape ecology deals with the patterning as Wuhan, China. of ecosystems in space and time. It emphasizes Wuhan, a metropolitan area in Hubei province, the interaction between spatial patterns and eco- is in the centre of China. The city lies at the junc- logical processes, and the causes and conse- tion of the Yangtze River and the Hanjiang River, quences of spatial heterogeneity across a range where rapid urbanization has occurred. It is of scales (Turner et al., 2001). One approach known as the ‘hundreds-of-lakes-urban’ because to achieving better understanding and character- it has many lakes (Figure 1). Until 2003, there ization of the changes in urban wetland were a total of 138 lakes whose areas were larger 2 landscapes lies, therefore, in analysis of wetland than 0.1 km in the city, mainly connected to structure, spatial-temporal pattern, ecological Caidian, Huangpi, Jiangxia, and Dongxi Lakes. process, and driving mechanism using landscape They accounted for 20% of the total lakes in the ecological methodologies and theories. main city areas (Zhang and Deng, 2005) and con- To date, most research has focused on analy- sisted of typical natural wetland landscapes (river ses of spatial-temporal dynamic change in land- wetlands, lake wetlands, bottomland wetlands, scape structures (Frohn, 1998; Turner et al., and marsh wetlands) and artificial wetland land- 2001; Tang et al., 2007). Others have studied the scapes (reservoir and pond wetlands) in the urban ecological planning, design, and management of areas of Wuhan. They played an important part in landscapes by using landscape ecological con- balancing the ecosystem, maintaining the water cepts and metrics (Berger, 1987; Pauleit and cycle, connecting rivers and lakes, and preventing Duhme, 2000; Jim and Chen, 2003; Corry and or controlling flooding in Wuhan. Thus, there is, Nassauer, 2005). Some research has focused historically, a close relationship between the evo- on biodiversity conservation and ecological lution of the wetlands and the urban development

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II Field area, data sources, research methods and research design 1 Field area Wuhan belongs to the transition zones from the southeastern highlands to the foothills in the south piedmont of Dabie Mountain, and covers from E113410 to 115050 in longitude and from N29580 to 31220 in latitude. The middle part is low and flat, while the south part and north part are hills. The landform types of Wuhan belong to the alluvial plain of the rivers. The climate of Wuhan is semitropical monsoon ranging from hot, humid, and rainy summers to cold winters. The multiyear average of sunshine hours is 2057. The average temperature and annual rainfall is 16.3Cand Figure 1. Maps and imagery of Wuhan, Hubei 1220 mm, respectively. The altitude in the region Province of China is less than 50 m. The soil types vary, with the largest area having paddy field soil, covering in Wuhan. However, with the rapid development about 45.5% of the total area (Wang et al., 2008). of the economy, the continuous growth of the population, and the accelerated urbanization in 2 Data sources Wuhan in recent years, overexploitation of the urban areas has taken place in the areas The data sources of this study include the terrain adjacent to wetlands. As a result, urban wetland map of Wuchang county for 1993, with a scale of areas have strikingly decreased in extent, water 1:50,000; the land-use map of Wuhan for 1995, quality has deteriorated, ecological function with a scale of 1:100,000; the Landsat-TM ima- has been disturbed, and the flood-prevention or geries of Wuhan urban areas for September flood-mitigation ability of the rivers and lakes has 1987, September 1994, April 2000, and April been lowered. In total, the social and economic 2005, with a resolution of 30 m; and the statisti- sustainable development of the wetland regions cal data from the Hubei Statistical Yearbook on has been seriously affected, while flooding is Wuhan urban wetlands from 1953 to 2005. increasing (Deng, 2005). The objective of this paper is, therefore, to 3 Wuhan urban wetland landscape types, analyze changes in the urban wetland landscape coding, and definitions pattern and the driving mechanisms for this from According to the state land-use classification 1987 to 2005 in Wuhan, China, and to gain a bet- system, the urban wetland landscape of Wuhan ter understanding of the historical evolution of is divided into five wetland types: river wet- the process, causes, and recent changes, using lands, lake wetlands, reservoir and pond wet- landscape ecological methodologies and the- lands, bottomland wetlands, and marsh ories. This understanding will provide important wetlands. These wetland types are based on the information to assist in the planning and mainte- classification system used in landscape ecology nance of sustainable urban wetlands, and to and the characteristics of the urban wetlands of enhance the services of the urban wetland Wuhan derived from TM satellite imagery’s landscape. spectral characteristics. The types, coding, and

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Table 1. Landscape coding, types, and definitions of Wuhan urban wetlands Coding Types Definitions 41 River wetlands The land below natural or artificial formation of rivers and perennial water main channel 42 Lake wetlands The land below naturally formed areas of perennial water level 43 Reservoir and pond The land below construction of artificial recharge of perennial water level wetlands 46 Bottomland wetlands The land between water-flow period and floodwater level of rivers 64 Marsh wetlands The land of surface-growth wet plants and flat, low-lying topography, the chronically damp, the seasonal perennial water or stagnant water

Figure 2. Wuhan urban wetlands in 1987, 1994, and 2005 definitions of the urban wetland landscape of analyzed with respect to their statistical, spatial, Wuhan are shown in Table 1. heterogeneous, and complex characteristics from 1987 to 2005. These analyses not only build a foundation for further analyzing the changes in 4 Research methods and research design the Wuhan wetlands, but also provide the ratio- The wetland system is self-organizing and com- nale for exploring and planning the sustainable plex in nature, which exhibits a discontinuous development of urban wetland resources. character in time-space as well as a conspicuous Six steps were taken in analyzing the changes non-linearity. Change in wetlands results from a of Wuhan urban wetlands. First, the Landsat-TM combination of natural, social, human, and other images were processed using the ERDAS factors. The spatial pattern of wetland landscapes IMAGE software system. Second, the Wuhan contains different types of wetland patches and urban wetlands spatial database and attribute the spatial and temporal characteristics of the database of 1987, 1994, and 2005 were estab- landscape can reveal the evolution of the wet- lished by using ArcGIS in combination with lands through a quantitative analysis of the land- Landsat-TM imageries, 1993 terrain map, and scape pattern. Therefore, the spatiotemporal 1995 land-use map. The results can be seen in evolution of the Wuhan wetland landscape was Figure 2. Third, using the databases mentioned

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Figure 3. Calculation flowchart of landscape ecological indices of urban wetlands above, the statistical and spatial change charac- of these indices have substantial overlap in their teristics of the Wuhan urban wetland landscape use and interpretation (Giles and Trani, 1999; were analyzed using the patch number, patch Tischendorf, 2001). In order to reduce the redun- area, average patch area, patch area variance, dancy in the use of these indices, we selected the and other characteristics. Fourth, the landscape patch-based and heterogeneity-based indices ecological indices of the Wuhan wetlands were that have the least mutual correlations but which calculated using common landscape ecology possess complementary ecological meanings. indices. Fifth, the Wuhan urban wetlands’ spa- These included: diversity index (H), dominance tiotemporal change characteristics, evolution index (D), evenness index (E), fragmentation processes, and driving forces for the past 19 years index (F), landscape shape index (LSI), and frac- were quantitatively analyzed using canonical tal dimension (FD). Among these indices, the correlation analysis. The research design is LSI and FD are the patch-based indices that shown in Figure 3. Finally, some recommenda- characterize the configuration of the individual tions were formulated to better develop, recover landscape class at the whole landscape scale and reconstruct a positive eco-environment and (Forman and Godron, 1986; Schumaker, 1996; to promote sustainable development in Wuhan Chuvieco, 1999; Imbernon and Branthomme, urban areas. 2001). Regarding the spatial heterogeneity- based indices, we chose H to describe the landscape diversity, D to measure to what extent 5 Selection and calculation of the landscape several principal landscape types control the ecological indices of the Wuhan wetlands whole landscape, E to measure the even degree Landscape ecological theory provides a set of of different landscape types, and F to measure quantitative tools (namely landscape indices or the landscape fragmentation. These indices have metrics) to characterize landscapes and to mea- been widely used to provide useful information sure a region’s landscape changes through time on biophysically changed phenomena associated (Reed et al., 1996). It is widely accepted that a with patch fragmentation at large spatial scales general association exists between landscape (Viedma and Meliaˆ, 1999; Fuller, 2001). The patterns and ecological processes (O’Neill calculation methods used to derive the landscape et al., 1988; Turner et al., 2001). However, many ecological indices are shown in Table 2.

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Table 2. Calculation methods and definition of landscape ecological indices Landscape ecological Type indices Formulae Meanings Heterogeneity- Diversity index Pm Reflects the type of urban wetland landscape H ¼ ðÞPi lgðÞPi based indices (H) i¼1 of Wuhan and the portion of uniformity. The greater the H value, the larger the diversity of Wuhan wetland types. Dominance D ¼ Hmax H Measures one or a few types of wetland index (D) Xm landscape dominant players for different ¼ Hmax þ ðPiÞlgðPiÞ wetland landscape pattern. The greater the D i¼1 value, the larger the differences in landscape types. Pm Equality Reflects the uniform distribution in the dif- ðÞPi lgðÞPi index (E) E ¼ H ¼ i¼1 ferent types of wetland landscapes. The Hmax lgðÞm greater the E value, the more uniformity in the composition of the wetland landscape. Fragmentation Pm Refers to the degree of wetland landscape F ¼ ðÞNi=A index (F) i¼1 being divided into parts, and reveals the degree of impact of human activities on the pattern changes of a wetland landscape. pffiffiffiffiffiffiffi Patch-based Landscape LSI ¼ Li 2 pAi Represents the complexity of the geometric indices shape index shape of the wetlands. It could indirectly (LSI) reflect the degree of human activities in the wetlands. Fractal dimen- FD ¼ 2 lnð0:25LiÞ Reflects the self-organization and complexity sion (FD) lnðAiÞ of the wetland landscape patch. It could indirectly reflect the degree of interference. m is the type of numbers of wetland landscape; i is patch type; A is the total area of wetland landscape; N is the total number of patches; L is the total perimeter of wetland landscape; Ai is the area of the ith wetland landscape area; Pi is the proportion of the ith wetland landscape area to the total area; Ni is the total patch number of the ith landscape types; Li is the total perimeter of the ith landscape; H is the diversity index; Hmax is the largest in uniform under the conditions of the diversity index.

III Results from 1987 to 2005 (Figure 4, A–B and D–F). The only exception is that the average patch area 1 Changes in the characteristics of the increased by 2.71% from 1987 to 1994, and then Wuhan urban wetland landscape pattern decreased 1.71% from 1994 to 2005, but the Regional characterizations of the patterns and general trend showed a 1% increase from 1987 changes in the urban wetland landscape from to 2005 (Figure 4C). Overall, the area of the 1987 to 2005 are summarized in Figure 4. The Wuhan urban wetlands decreased by 8.11% total number of patches, total areas, patch area during the 19-year period. variance, maximum patch area, and the Similarly, the total areas of the river wetlands, minimum patch area of the Wuhan wetland land- lake wetlands, bottomland wetlands, and marsh scape gradually decreased by 9.82%, 8.11%, wetlands also decreased by 13.36%, 18.71%, 10.11%, 15.61%, and 31.17%, respectively, 6.16%, and 50.33%, respectively. In contrast,

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Figure 4. Histograms showing the statistical characteristics of changes in the Wuhan urban wetland landscape from 1987 to 2005: (A) patch number; (B) total area; (C) average patch area; (D) patch area variance; (E) maximum patch area; (F) minimum patch area the total area of the reservoir and pond wetlands wetlands and marsh wetlands decreased by increased by 47.75% from 1987 to 2005 17.79%, 18.71%, 1.12%, 15.61%, 26.94%, (Figure 4B). Overall, the natural wetland area 50.33%, 32.02%, and 45.31% from 1987 to decreased. In particular, the lake wetlands and 2005, respectively (Figure 4, A–C and E). These marsh wetlands decreased sharply, while the changes are due to the fact that the larger lake artificial wetland areas increased in Wuhan. wetlands and marsh wetlands were divided into The patch numbers, the total areas, the aver- smaller ones. These fragmentations resulted in age patch areas, and the maximum patch of lake the decline of the Wuhan lake wetlands and

Downloaded from http://ppg.sagepub.com at PURDUE UNIV LIBRARY TSS on April 8, 2010 213 214 Progress in Physical Geography 34(2) marsh wetlands, since the ecosystem of small lakes and marsh wetlands is fragile and tends to decline either naturally or artificially (Deng, 2005). Our analysis further indicated that the human disturbance in the lake wetlands and marsh wetlands increased due to the increase of population and economic development over the region during the past 19 years in Wuhan.

2 Heterogeneity analysis of Wuhan urban Figure 5. Heterogeneity analysis of Wuhan wetland landscape pattern wetland landscape pattern from 1987 to 2005 The analysis of heterogeneity is mainly designed to human activities increased from 1994 to 2005. reveal landscape diversity, dominance, evenness, Nevertheless, the general trend of H, E,andF and fragmentation in size and distribution of decreased from 1987 to 2005, and the general patches in the landscape. It is preferable to adopt trend of D increased for the same period. these indices when speculating on a spatial pattern because landscape patterns possess both homogeneous and heterogeneous attributes. The H, D, E, 3 Complexity analysis of Wuhan urban and F are calculated based on heterogeneity indices wetland landscape pattern that reflect spatial heterogeneity by quantifying the The analysis of complexity is designed to reveal spatial structures within the landscape. the degree of complexity of the spatial patch prop- Using the spatial and attributes databases of erties in a wetland landscape and assess the impact 1987, 1994, and 2005 of the Wuhan urban of anthropogenic activities. The analysis can sug- wetland landscape mentioned above, and the for- gest the degree of impact of human activities on mulae in Table 2, the H, D, E,andF values can the pattern change of the wetland landscape. The be calculated (Figure 5). The H, E,andF were the LSI and FD values are the most important indices largest and D was the smallest in 1987 (Figure 5). of the analysis. For examples, Rex and Malanson The results show that the diversity of the Wuhan (1990) reported that there was a significant rela- wetland resource was largest in 1987, comprising tionship between FD and the impact of human lake wetlands, river wetlands, and reservoir and activity on the riparian forests in Iowa. Wickham pond wetlands. In addition, the results also showed et al. (1994) found that the FD of the wetlands that the patches in the Wuhan wetland landscape increased as the number of agricultural and resi- were distributed evenly, and the impact from dential land-cover components of the landscape human activities was the lowest in 1987. pattern types increased. Liu and Cameron (2001) The values of H, E,andF decreased, while the found that there was a significant difference in the value of D increased from 1987 to 1994. These fractal dimension of the wetlands when classified changes indicate that the later Wuhan wetland according to land use, vegetation type, size, and landscape tended to be more homogeneous, and level of human disturbance. Zhang et al. (2004) the diversity decreased while the impact from found that FD can be used to show the relationship human activities increased. The values of H, E, between the spatial structure and the pattern of the and D slightly increased while F decreased from wetland resources. In contrast, others have demon- 1994 to 2005. These changes show that the most strated that the FD of the wetlands decreases as the recent Wuhan wetland landscape became surrounding agricultural and human land use gradually more diverse, while the impact from increases (Forman and Godron, 1986).

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Figure 6. (A) LSI and (B) FD analysis of Wuhan wetland landscape pattern from 1987 to 2005

The present analysis reveals that the LSI and increased over the past 19 years. The dry climate FD of the bottomland wetlands were the smal- has resulted in a reduced amount of water in the lest, while the LSI and FD of the reservoir and rivers and lakes. Along with a rapidly increasing pond wetlands were the largest (Figure 6). The population, the degree of development and utili- results indicated that the shape of the bottomland zation of marsh wetlands and bottomland wet- wetlands was the simplest and the impact of lands were increased. As a result, many marsh human activities there was the smallest, while wetlands and bottomland wetlands have been the shape of the reservoir and pond wetlands was replaced by agricultural land, while the reservoir the most complex and the impact of human and pond wetlands have been replaced by refined activities was the largest over the past 19 years. fishponds (Deng, 2005). These analyses suggest that the impact of human activities on the natural landscape was smaller than that on the artificial landscape (eg, reser- IV Discussion voirs and ponds). The Wuhan urban wetlands are mainly distribu- The LSI and FD of the river wetlands ted along the Jianghan Plain (an alluvial plain and marsh wetlands reduced from 1987 to along the Yangtze River and the Hanjiang River; 2005 (Figure 6). For the same period, the LSI Figure 2). The formation and evolution process and FD of the lake wetlands and bottomland of the Wuhan wetlands have a close relationship wetlands increased, and then decreased from with the Yangtze River since they were origi- 1994 to 2005. However, the overall trend of nally and directly connected. Before the 1980s, LSI and FD decreased from 1987 to 2005 all the lakes and reservoirs overflowed in the (Figure 6). The results suggest that the shapes flood season and separated from each other in of the river wetlands, marsh wetlands, lake the dry season. However, the natural connec- wetlands, and bottomland wetlands became tions among the Yangtze River, river wetlands, simpler and their self-similarity decreased. lake wetlands, and reservoir wetlands have However, the impact of human activities reduced since the 1980s due to economic devel- increased from 1987 to 2005, while the LSI and opment, population growth, and accelerated urba- FD of the reservoir and pond wetlands nization (eg, the construction of a flood-control increased from 1987 to 1994, and then dykes, sluice gates, and pumping stations). These decreased from 1994 to 2005. The overall trend changes have affected the flood course of the showed an increase from 1987 to 2005 (Figure Yangtze River and the storage function of the lake 6). These results indicate that the shape of the wetlands and reservoir wetlands, and have also reservoir and pond wetlands tended to become cut off the biological connections and reduced the more complex and that the self-similarity biodiversity and biomes.

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Table 3. Canonical loading of landscape indices by canonical correlation analysis Canonical loading Canonical Canonical Canonical Canonical Variable Meaning variable 1 variable 2 variable 3 variable 4 variable Landscape ecological indices Y Y1 D –.489 .418 .765 .630 Y2 E .734 –.240 –.623 –.125 Y3 F –.436 .296 .850 .016 Y4 H .265 .865 –.310 .294 variable Social factors X X1 GDP –.131 –.779 –.612 –.031 X2 Cultivated land area .059 .915 –.380 .118 X3 Total population –.103 –.921 .376 .013 X4 Gross output value of agriculture, forestry, –.421 .477 .016 .771 animal husbandry and fishery X5 Area of aquatic farming .055 –.957 .186 –.215

Figure 7. The annual average (A) temperature and (B) precipitation at Wuhan from 1985 to 2005 from the China Statistical Yearbook of 1985 to 2005

Using canonical correlation analysis methods 1 Role of regional temperature and (see discussion below and Table 3), we found a precipitation significant relationship between urban wetland There is a close relationship between the landscape ecological indices and socio-economic region’s temperature and the precipitation and factors. In addition, the large-scale reclamation the wetland area. The annual average tempera- of the lakes and rivers has caused the wetland ture of Wuhan increased each year, but the ecosystem to deteriorate; as a result, the wetland annual precipitation remained unchanged from biodiversity has decreased, but flood disasters 1985 to 2005 (Figure 7). Evaporation also gra- continue to increase. The natural, social, and dually increased during the past 21 years, and human activities thus combine to cause these the climate of Wuhan became warmer and changes. dryer. This was key to changing the shape and

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Figure 8. Change chart of (A) total population and (B) GDP and its composition of Wuhan from 1985 to 2005 from the China Statistical Yearbook of 1985 to 2005 structure of the Wuhan wetland landscape pat- analysis methods. X is the independent variables tern, especially the transformation from marsh related to socio-economic factors from the wetlands to grassland and farmland. Hubei Statistical Yearbook of 1985 to 2005, and Y is the standard variables related to urban wetland ecological indices. We identified five inde- 2 Role of population increase and pendent variables as common factors using economic development factor analysis before the correlation analysis, The Wuhan population increased and the econ- in order to reduce mutual interference between omy was developed rapidly between 1987 and the independent variables. 2005. These were the major factors causing the The first variable is E and its typical load is changes in the Wuhan wetland landscape pattern 0.734, with negative correlation to gross output (Figure 8). Particularly, the country’s grain values of agriculture, forestry, animal husban- production in Jianghan Plain increased dramati- dry, and fishery, and GDP (canonical loading cally, while the population increased and the is –0.421 and –0.131, respectively). This indi- economy developed rapidly. The population of cates that E decreased with the growth of GDP Wuhan increased from 6.084 million people by and gross output value of agriculture, forestry, the end of 1985 to 8.014 million people by the end animal husbandry, and fishery. Correspond- of 2005 (Figure 8A). The Gross Domestic Product ingly, marsh near urban areas was turned into (GDP) of Wuhan also increased from 9.732 bil- arable land or building sites, or converted into lion yuan in 1985 to 223.8 billion yuan in 2005 ponds for fishery, and E declined with the (Figure8B).Atthesametime,primary,second- decrease of area of marsh wetlands from 1987 ary, and tertiary industry showed a strong growth to 2005 in Wuhan. trend (Figure 8B). Such rapid population growth The second variable is H and its typical load and economic development certainly have had a is 0.865, with negative correlation to the area profound effect on the scale, structure, distribu- of aquatic farming and total population (cano- tion, and intensity of land use in Wuhan. This will nical loading is –0.957 and –0.921, respec- inevitably affect the structure, scale, and distribu- tively), indicating that H decreased with the tion of the Wuhan urban wetland landscape. growth of the area of aquatic farming and total Table 3 provides the results of a quantitative population. Artificial enclosure to support analysis of the relationship between urban wet- aquatic culture in the lakes was the factor that land landscape ecological indices and socio- determined the reduction in area of the lake economic factors, using canonical correlation wetlands, which led to H decreasing with the

Downloaded from http://ppg.sagepub.com at PURDUE UNIV LIBRARY TSS on April 8, 2010 217 218 Progress in Physical Geography 34(2) simplification of wetland types from 1987 to massive mixed feed pouring accelerated the 2005 in Wuhan. pollution of the urban lake wetlands, reduced The third variable is F and its typical load is the lakewater transparency, lowered the biodi- 0.85, again with negative correlation to GDP versity of the whole lake region, and degraded and cultivated land area (canonical loading is – the ecosystem of the urban lake wetlands. 0.612 and –0.38, respectively), indicating that Simultaneously, the areas of lake wetlands F decreased with the growth of GDP and culti- sharply decreased from 904.99 km2 in 1987 vated land area. With population increase and to 735.67 km2 in 2005, and affected the lake the development of the economy, more wetland storage function, which led to the frequent area is required for housing, transportation, pub- occurrence of flood disasters. lic facilities, and recreational facilities, and F decreased, also reflecting the division of larger wetlands into smaller ones from 1987 to 2005 in 4 Role of accelerated urbanization and the Wuhan. rapid expansion in Wuhan The fourth variable, D, is distinct in behaviour The accelerated urbanization and the rapid from the other variables. Its typical load is –0.30, expansion of urban and real estate development with a positive correlation to gross output value resulted in lake and pond wetlands of Wuhan of agriculture, forestry, animal husbandry, and urban and peri-urban being filled and occupied fishery (canonical loading is 0.771), indicating with residential housing or industrial land. that D increased with growth in these. This is Statistical analyses show that the Wuhan urban explained by the fact that, with the decrease in lake surface, especially in the Hankou region, area of lake wetlands and marsh wetlands, there reduced by 154.6 km2 and then decreased by was a simplification in wetland types, between nearly 60% due to subsequent reclamation and 1987 and 2005 in Wuhan. occupation. As a result, Neisha Lake reduced in area from 0.39 km2 to 0.03 km2; Waisha Lake from 4.73 km2 to 4.23 km2; and Houxian Lake 3 Role of artificial enclosure from 0.17 km2 to 0.04 km2. Eight lake wetlands Artificial enclosure for aquatic culture in the no longer exist. In addition, the building of lakes was the factor that determined the rapid Hankou Zhongshan Road, Jiefang Road, and reduction in the area of natural wetlands and Hankou Railway Station took away a large num- rise in the artificial wetlands in the middle of ber of lake wetlands. Furthermore, Nan Lake, the 1980s. The areas of the Wuhan reservoir Shai Lake, Simeitang Lake, and Tangxun Lake and pond wetlands increased rapidly from inundated residential property from time to time 302.34 km2 in 1987 to 446.71 km2 in 2005. (Zhang and Deng, 2005). LSI and FD of the river The artificial enclosure for aquatic culture in wetlands, marsh wetlands, lake wetlands, and the lakes resulted in overharvesting of water bottomland wetlands decreased, while the LSI grass, accelerating the loss of biodiversity of and FD of the reservoir and pond wetlands the aquatic plants and weakening the self- increased from 1987 to 2005. The results purification ability of the lake wetlands. The indicate that the shape of the river wetlands, results made the LSI and FD of the reservoir marsh wetlands, lake wetlands, and bottom- and pond wetlands increase from 1987 to land wetlands become simpler and their self- 2005 (Figure 6). The shape of the reservoir and similarities decreased. However, the shape of pond wetlands tended to become more com- the reservoir and pond wetlands tended to plex and the self-similarity increased over the become more complex and the self-similarity period. In addition, excessive breeding and increased over the past 19 years.

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V Conclusions comprehensive measures can be utilized to save Using landscape ecological indices, we exam- and restore the positive services and functioning ined spatiotemporal evolution characteristics of Wuhan urban wetland ecosystems, such as and dynamic changes in the pattern of urban returning farmland to lakes, opening the flood wetland landscape in Wuhan from 1987 to storage to the lakes, dredging the expansion 2005. TM images, land-use maps, surveyed field lakes, and controlling pollution. Moreover, data, and statistical data on Wuhan wetlands slowing down wetland degradation caused by were used to support the analysis. We found that: human activities is important to recovering and rebuilding the damaged wetland ecosystem and (1) Urban wetland area decreased by to maintaining the balance between the supply 137.5 km2; natural wetland area decreased of the renewable natural resources and the needs by 281.87 km2; and artificial wetland area of humans. To have sustainable urban develop- increased by 144.37 km2. ment, the services and advantages of wetland (2) The types of urban wetlands became less ecosystems should be preserved wherever possi- homogeneous, because the value of H, E, ble in Wuhan. and F decreased, while the value of D Acknowledgements increased from 1987 to 2005. In addition, we also found that LSI and FD of the river We appreciate the support by the Special Fund for wetlands, lake wetlands, bottomland wet- Basic Scientific Research of Central Colleges (no. CUGL090232), China University of Geosciences lands, and marsh wetlands decreased, (Wuhan), and the Research Plan Project on Soft while the LSI and FD of the reservoir and Science of Wuhan (no. 200940833385-02). pond wetlands increased. (3) There is a close interaction between the References landscape ecological indices and socio- Berger, J. 1987: Guidelines for landscape synthesis: some economic factors (GDP, cultivated land directions-old and new. Landscape and Urban Plan- area, total population, gross output value ning 14, 295–311. of agriculture, forestry, animal husbandry, Chuvieco, E. 1999: Measuring changes in landscape pat- fishery, and area of aquatic farming), as tern from satellite imageries: short-term effects of fire revealed by canonical correlation analysis, on spatial diversity. International Journal of Remote indicating that the changes of types, num- Sensing 20, 2331–46. bers and total areas of urban wetlands in Corry, R.C. and Nassauer, J.I. 2005: Limitations of using Wuhan were at least partly caused by urba- landscape pattern indices to evaluate the ecological nization and development of the economy consequences of alternative plans and designs. Land- from 1987 to 2005. scape and Urban Planning 72, 265–80. Deng, H.B. 2005: Research on Jianghan lake groups and Our research also suggests that ecological land- evolution and lake area regional sustainable develop- scape methodologies can be used as a basis ment. Beijing: Economic Science Press (in Chinese). for decision-making in the appraisal of wetland Forman, R.T.T. and Godron, M. 1986: Landscape ecology. environments and for utilizing wetland New York: Wiley. Frohn, R.C. 1998: Remote sensing for landscape ecology: resources in a sustainable way. In order to max- new metric indicators for monitoring, modeling, and imize the services of the Wuhan urban wetlands, assessment of ecosystems. Boca Raton, Florida: Lewis we suggest that appropriate adjustment of the Publishers. adjacent land use is a critical component in Fuller, D.O. 2001: Forest fragmentation in Loudoun Wuhan urban wetland conservation. At the same County, Virginia, USA evaluated with multi-temporal time, biological and engineering technology and Landsat imagery. Landscape Ecology 16, 627–42.

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