| Land use refers to the activity of people using land as a carrier to obtain various products and services.As the most direct reflection of human activities on land,land use change plays an important role in Global change.Ecological risk refers to the risk borne by an ecosystem or its components within the scope of natural or human activities.It refers to the potential harm caused to the ecosystem or its components by various unexpected events or disasters in a specific area.In recent years,with the increasingly prominent ecological environment problems in the context of Global change and the popularization of remote sensing information applications in the era of Big data cloud platform,ecological risk assessment has received great attention from academia,ecosystem managers and the whole society.Mastering the process of land use change and its ecological risks can provide decision-making support for optimizing land resource allocation,maximizing land use benefits,and avoiding ecological risks.At present,people are increasingly paying attention to ecological risks and conducting many effective studies.Literature analysis shows that there are certain limitations.Existing research mainly focuses on retrospective ecological risk assessment,but there is relatively insufficient exploration of different development trends of future ecological risks and optimization of land spatial patterns.Therefore,a comprehensive analysis of the changing characteristics of ecological risks,exploring response mechanisms for ecological risks in different future scenarios,and taking effective measures to regulate ecological risks are of great significance for the construction of a new pattern of regional protection.Taking Lanzhou,an important ecological barrier area in northwest China,as an example,this study first simulated the land use pattern of Lanzhou in 2025 under natural development scenarios,cultivated land protection scenarios,and ecological priority scenarios with the help of MCE-CA-Markov model.Secondly,the land use simulation is used as an incentive to build an ecosystem service model,calculate the ecosystem service value of Lanzhou in 2020 and 2025,and then build an ecological risk assessment model based on changes in ecosystem services,predict the ecological risk index in the region,and explore the spatial distribution and change characteristics of ecological risks under the three scenarios in the region;Finally,according to the characteristics of land use change in Lanzhou City and the prediction results of ecological risks,optimize the land use pattern in different regions,take effective measures to regulate ecological risks to improve the spatial pattern of land use,enhance the ability to prevent ecological risks,and promote the coordinated development of Urban ecosystem and social economy.The main results of this study are:(1)Dynamic analysis of land use change in LanzhouIn 2025,the spatial distribution of land use pattern under three scenarios in Lanzhou City will be dominated by grassland,followed by cultivated land,construction land and forest land.In the natural development scenario,the development trend of urban construction land is significant,and its development space continues to expand and extend.In the scenario of farmland protection,outside the scope of the basic farmland protection zone,the construction land shows an upward trend,which is controlled compared to the natural development scenario,and the stability of the regional ecosystem is significantly improved.In the context of ecological protection,the growth of urban construction land is greatly restricted,resulting in a balanced spatial distribution of construction land and a more reasonable structure and layout of construction land.(2)Scenario prediction of ecosystem services in Lanzhou CityThe total ecosystem service value under different scenarios in 2025 is ecological priority scenario>farmland protection scenario>natural growth scenario.Compared with 2020,the overall value of the four types of ecosystem services shows a trend of regulation services>support services>supply services>cultural services.The proportion of ecosystem service value of each land use type in the research area is in order:grassland>cultivated land>forest land>water body>unused land>construction land.Compared with the ecosystem service value in 2020,the ecosystem service value of cultivated land in Lanzhou City only decreases under the natural development scenario,and the ecosystem service value under the cultivated land protection scenario is the largest;Under the three scenarios,both forest land and water bodies are in a stable upward trend;The ecosystem service value of grassland only decreases in the natural development scenario,while it shows an upward trend in the farmland protection scenario and ecological priority scenario,and the ecosystem service value is the highest in the ecological priority scenario;The value of ecosystem services for unused land can be ignored in three scenarios;The contribution of construction land is 0.It can be seen that forest land and water bodies are the main contributors to the growth of ecosystem service value.(3)Spatial distribution of ecological risk in Lanzhou City under multi scenario simulationThe ecological risks in 2020 and 2025(under three scenarios)are dominated by low and medium low risks,and the sum of the two accounts for more than half.The proportion of medium risk areas is moderate,and the proportion of medium high and high risk areas is relatively small,indicating that Lanzhou has a good ecological environment.Specifically,under the natural development scenario,the area of low,medium,and low risk areas in 2025 has decreased compared to 2020,while the area of medium,medium,and high ecological risk areas has shown an increasing trend.In the scenario of farmland protection,the area of low,medium,and medium risk areas in 2025 has decreased compared to 2020.This is related to the policy of farmland protection,which limits the indiscriminate expansion of construction land,protects farmland,reduces ecological risk index,and ultimately improves the area of medium,high risk areas.Under the ecological priority scenario,the area of low and medium risk areas in 2025 shows a downward trend compared to 2020.Low to medium,high to medium,and high-risk areas show a slight increase trend.The main reason is that in this scenario,the transformation of ecological land is restricted,its stability is increased,and its loss rate is controlled.Overall,the order of ecological risks from high to low is natural development scenario>farmland protection scenario>ecological protection scenario.In the three scenarios,the ecological priority scenario fully considers the basic requirements of sustainable development of ecological environment and urban space coordination,strictly manages the land use and development intensity of the municipal government,encourages land conservation,improves the ecological environment quality,and better meets the strategic needs of sustainable development of Lanzhou City.(4)Land use optimization measures and ecological risk control measures in Lanzhou CityIncrease the greening of urban areas in high-risk areas,improve ecological benefits,reduce soil erosion and precipitation evaporation losses,and build urban "ecological corridors" with the Yellow River as the main body through the city,forming an ecological layout of green landscapes along the river.Medium-risk stable zones are mostly plants with good growth patterns,or forest parks,etc.,and the regulatory measures that can be taken mainly include three aspects.First,relevant government departments implement the land greening system,increase forest coverage,and implement mechanisms to effectively protect the long-term development of forest and grass resources;Second,mountains and forests and other natural landscapes are rich in resources,which have various ecological functions such as regulating climate,conserving water sources,protecting carbon and oxygen balance,and enhancing the maintenance of key areas such as forest parks;Third,in accordance with the overall strategic requirements of ecological priority,accelerate the development of the ecological model of"Shanshui City".Low-risk conservation zones have good natural heritage,and should take natural restoration as the main body and biological and engineering measures as the auxiliary measures to manage natural disasters and soil erosion,optimize ecosystem structure,system stability and function,and promote the regeneration of regional biodiversity. |
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