| Hang-Jia-Hu Plain is considered one of the earliest locations of rice agriculture development and one of the most important paddy bases in eastern coastal China.It has been experiencing rapid urbanization and economic development since 1979,however,dramatic increased built-ups encroached on a significant portion of the paddy fields here along with the rapid economic growth of the post-reform period from 1980 to 2010.It has affected local food security and degraded the landscapes of paddy fields and impacted their capacity to deliver ecosystem services,such as climate regulation,flood control,soil organic carbon storage,environmental protection,and the provision of an aesthetic landscape.It is urgent to identify the dynamics of paddy field patterns in response to urbanization,and provided the implications for sustainable development in this region.In this study,we integrate GIS,gradient analyses and landscape metrics to characterize the different modes of paddy field loss,identify the driving factors,distinguish the dynamic patterns of paddy field in response to urbanization,explore the change of paddy ecosystem services values influrenced by the change of human needs,and then disscuss the protection policies for decision-making processes to achieve regional sustainability.The main contents and conclusions were summarized as follows:(1)This study characterized the general trend of urbanization in the Hang-Jia-Hu Plain from 1980 to 2010,and distinguished the different modes of paddy field loss.Results showed that the area of Hang-Jia-Hu Plain account for 7.56%of Zhejiang province,and the area of paddy fields of level I accounted for 47.23%.However,urban land expanded to nearly four times that of the initial area during 1980-2010 and that 88%of new urban land was developed on paddy fields.In 2010,land development intensity was 23%which was exceeded the ivable land development line(20%),and approaching to the warning line of 30%.Extensive built-ups expansion intensified the contradiction between human and land,and paddy field of the highest quality became the first victim of urbanization.The loss of paddy field exhibits spatial autocorrelation,and spatial aggregation increased gradually.It is indicated that the paddy field around the built-ups was easily to be encroached.Local autocorrelation analysis shows that the extensive occupation was firstly observed in the noutheast of Hang-Jia-Hu Plain and then extended to the southwest.Moreover,the extensive occupation occurred on the urban periphery,along the highway,dispersed in the rural area.(2)The changing patterns of paddy fields in response to various urban expansion patterns in the Hang-Jia-Hu Plain from 1980 to 2010 were characterized.Our results demonstrate that the urban built-up area increased significantly,but the population-based urbanization lagged behind the land-based urbanization and the growth of urban was unreasonble.Moreover,various urban expansion styles differentially influenced the patterns of paddy fields.In autonomous expansion cities,sprawled urban land mainly occupied paddy fields in urban centers.However,the irregular expansion of passive expansion cities encroached on a number of paddy fields in the urban fringe where the landscape of urban patches and paddy fields was more complex and irregular in shape.Furthermore,the urbanization curve implies that future urbanization efforts will focus on the passive expansion cities,indicating that paddy fields still face the risk of disruption.We suggest that the boundary of urban development should be restricted,permanent paddy reserves should be delimited,and ecologically oriented management systems that target paddy field protection should be implemented to ensure the sustainable development of this region.(3)Highway construction has accelerated urban growth and induced direct and indirect changes to land use.This paper explores the interaction between the impact of highways and paddy field loss.Results showed that the Hang-Jia-Hu Plain experienced extensive highway construction during 1990-2010,with a clear acceleration of expressway development since 2000.This unprecedented highway construction has directly fragmented the regional landscape and indirectly disturbed the regional landscape by attracting a large amount of built-up land transition from paddy field from 1990 to 2010.In the highway-effect zone,serious farmland loss initially occurred in the urban region and then spread to the rural region.Moreover,we found that thethe discontinuous expansion of built-ups scattered the farmland in the rural region and expressway-effect zone.Furthermore,dramatic expansion of built-ups occurred in 200m near the highway,and the fast growth area of built-ups gradually shifted outward from the sides of the highways,and the fast growth area of built-ups construction of expressways attracted more and more built-up land and induced a large amount of land transition.Influenced by highway construction,rice fields was most vulnerable to encroach by built-ups,and the paddy field in 400m buffer was more complex.Construct of expressway made paddy field more unstable.Particularly,with the boom of e-commerce,the increasing requirements of highway construction for logistics have created a great threat to farmland in the 21st century.It will lead to dramatic land use/cover changes in Hang-Jia-Hu Plain,so it is important to integrate the multiple planning,such as national economic and social development planning,urban planning,land use planning,transportation system planning,and environmental planning.(4)Based on the spatial data analysis and landscape expansion index,we explore the spatiotemporal characteristics of rural area and the dynamic of paddy field in response to rural expansion.Result showed that the rural settlements concentrated with evident spatial variability,and the KDE increased gradully.Rural settlements increased significantly and smaller shape induced by the outflying expansion.From1980 to 2010,the development of rural settlements has experienced the diffusion-coalescence process,of merging,if not controls,rural settlement will diffuse in the future.Furthermore,rural expansion made paddy field more irregular and more complex.Various rural expansion styles differentially influenced the patterns of paddy fields.Paddy field became more complex induced by edge-expansion,and the paddy field will easily to converse to built-ups.Outflying mode made paddy field more irregular,increased the risk of pests and deteriorated the structure and ecological functions of paddy field.Therefore,the local government should strictly implement the policy of "increase and decrease connection of urban and rural construction land",abandoned and idle small-scale rural settlements should be consolidated and reclamed to paddy field to improve the quantity and quality of paddy field.Moreover,the planning of "production-life-ecology" should be built to seek a balanced and coordinated development between urban and rural areas.(5)Finally,we analysis of the evolution of the paddy ecosystem service value in response to human needs,the result suggest that paddy ecosystem provided the basic materials product,ecological security,and spiritual needs to human.According to the weight indicators of human needs,human physical needs gained from paddy ecosystem are gradually reduced,and ecological security and spiritual needs increased gradually.Intergrating the change of land use/cover change and human needs,paddy ecosystem service value was drcreased from 0.748 billion yuan in 1980 to 0.599billion yuan in 2010.With the people's living standards gradually improved,paddy ecosystem service constitutes of human needs also changed.Between 1980 and 2010,the paddy ecosystem value of ecological security and spirit increased drmaticlly,while the value of the physical needs decreased.By 2020,China will achieve all-round well-off,according to changes in characteristics of human needs,the spiritual value of paddy ecosystem will increase.On the whole,the ecological security value was the highest,espascially,it could purify and regulate the atmosphere.Secondly,it could purify and reserve water.Although indirect value provided by paddy ecosystem has gradually become the mainstream of human pursuit,but the original value of food production was irreplaceable.Therefore,based on food security,ecological and cultural values.should be maximized.However,the rapid urbanization in last three decades increased the inconsistent between paddy ecosystem services and economic development.Built-ups of urban built-up area,mileage of highway,and rural settlement area were significantly negatively correlated to paddy ecosystem service value,and the rural settlement area reduced the paddy ecosystem services value drmaticlly.Hang-Jia-Hu Plain is one of the fastest developing areas of China.However,traditional style of the rice culture and heritage had impacted by modern economic and social development drmaticlly.This study suggests that local governments should further improve the market-oriented protection system for paddy field,maintain the red line of farmland area,and improve the value of the paddy ecosystem services to meet human needs in different periods.In addition,balance the construction land and paddy field between urban and rural development.It is important to integrate the multiple planning and break the administrative boundaries and departmental boundaries to provide a scientific basis for decision-making processes to achieve regional sustainability. |
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