|Other Abstract||Land Use and Land Cover Change (LUCC) is an important part of environmental Change and sustainable development research. Simulation of future land quantity and spatial pattern is of great significance to regional sustainable development. At present, LUCC scenario simulation studies mainly focus on the short-term simulation of small and medium scale regions, which is inadequate to reflect the long-term trend change characteristics of large spatial scale. China's coastal zone is located in the transitional zone between the Eurasian continent and the Pacific Ocean, with a large space range and complex and diverse land use types. Intensity of human activities has strained land resources in coastal zones and altered ecosystems, thus increasing the complexity and uncertainty of dealing with the risks of global change. In view of this, in order to ensure the healthy and sustainable development of China's coastal zone, it is urgent to carry out long-term series multi-scenario LUCC simulation research on China's coastal zone.
China's coastal zone includes the mainland part, offshore islands and shallow sea/offshore waters. The boundary of the land region in this study is determined according to the administrative divisions of prefecture-level cities in the eastern coastal areas, and the sea area is the combined range of 10 km and 10 m isobath from the land-sea boundary of the administrative region. For this region, we are grasping the characteristics of land use change in coastal zone from 2000 to 2015 and analyzing the long-term economic and social development in the future. Based on SSP1-RCP2.6 (A), SSP2-RCP4.5 (B), and SSP3-RCP4.5 (C) scenarios, the SD-FLUS model was established. It is a model that combines top-down macro-area demand forecasting and bottom-up micro-space simulation. Through the model, the simulation results of multi-scenario land demand time series up to 2100 are obtained, as well as the simulation results of the spatial distribution of land use in 2020, 2025, 2030, 2035, 2040, 2050, 2060, 2070, 2080, 2090, and 2100. The main conclusions are as follows:
(1) The analysis of land use change characteristics in China's coastal zone shows that there are rich land use types in China's coastal zone, and the main land use types are cultivated land, woodland, shallow sea water and construction land. The land use in China's coastal zone shows a transitional pattern from sea to land, from shallow sea water to coastal wetland to constructed wetland to land mixed with multi-types mainly cultivated in the north and forested in the south. Considering the variation range of different species in the last 15 years, the overall variation range and rate slowed down gradually. The comprehensive index of land use degree showed a significant increasing trend, which indicated that the level and degree of intensification of land use in China's coastal zone is continuously increasing.
(2) Natural factors, such as climate differentiation, sea-land gradient and elevation differentiation, have significant effects on LUCC in the coastal zone. Human factors mainly include the number of population, level of economic development, industrial structure, level of urbanization and policy orientation. In addition, location factors represented by distance will significantly affect the distribution and changes of land use. In the future, the population growth rate will slow down and the economic development trend will be on the rise. The urbanization rate will gradually increase and will start to stabilize after 2050.
(3) The constructed SD model has a good simulation effect on the land quantity demand of multiple scenarios in the future period, and is universal in each coastal zone. It is a better way to understand the dynamic mechanism of land use change to construct the SD model with population and economy as the leading factors to simulate the future land demand in coastal zone. The simulation results show that the economic and social development in Scenic A is less dependent on land resources, and the demand for construction land and constructed wetland is relatively small, which is conducive to the protection and restoration of various ecological land types; Scenario B: The demand for land resources in economic and social development is in the middle of the three scenarios; Scenario C Economic and social development has significant demand for living and production land, construction land expands, cultivated land is seriously shrinking, and the area of natural ecological land type is relatively small.
(4) The FLUS model effectively simulates the spatial distribution of multi-scenario land use in the future. The simulation results show that although there are obvious differences between the multi-scenarios, on the whole, the trend of the expansion of Sansheng (production, life, ecology) space to the sea is still more significant. In Scenario A, the trend of centralized distribution and pattern optimization of land types is obvious. In Scenario B, the expansion of construction land and artificial wetlands and the shrinking of coastal forests and grasslands are obvious. In Scenario C, the expansion of construction land, artificial wetlands and cultivated land toward the sea is more significant. Cultivated land has decreased, inland water bodies have shrunk severely, coastlines have been artificialized, and human-land conflicts have intensified. Based on the comparative analysis of the results of multi-scenario simulation of China's coastal zone, relevant suggestions for the development, utilization and control of China's coastal zone space in the future are put forward.
China's coastal zone LUCC scene simulation studies in order to adapt to social development, formulate reasonable land use development in the new period, the control policy, to optimize the land space, medium and long term strategic decision making and measures for coastal zone area refinement to provide scientific support, to protect ecological environment of coastal zone, coastal zone comprehensive management ability, promoting the sustainable development of coastal area economic society has important scientific significance.|