| The natural geography of China’s northern ecologically fragile areas is complex,with serious interference from human activities and significant climate change impacts,and the sustainable development of the ecosystem faces serious challenges.The existence of the horqin sands affects the ecological security of the northern region of China,and its environmental condition has been widely concerned.In order to investigate the ecosystem health status of the horqin sands,this thesis selects a typical closed flow area between sand dunes and meadows as the study area,analyzes the land use change and transfer intensity through land use data,and obtains the ESV change law from the ecosystem service function and land use type respectively;Then,we obtained many data and constructed an eco-hydrological synergistic health evaluation model,analyzed the change characteristics of important indicators in the evaluation system and the eco-hydrological synergistic health status of the study area,and discussed its causes;According to the current health status of the study area,the ecological safety pattern in different periods was established,and the safety pattern of the study area was optimized with the help of arable land suitability evaluation to achieve a virtuous cycle within the ecosystem of the study area.The research results are as follows:1.During 1985-2021,dryland,shrubland and semi-shrubland were the three most dominant land use types in the study area,with other land use types accounting for a smaller proportion.In terms of land use transfer changes,the largest transfer out was from shrubland and semi-shrubland,and the largest transfer in was from dryland.The total Ecosystem Service Value(ESV)in the study area ranged from 1851.47×10~6 to2464.15×10~6.From the viewpoint of various service functions,hydrological regulation and climate regulation were the main ecological functions affecting ESV;from the viewpoint of land use types,semi-shrubland and shrubland were the main land types affecting ESV.In terms of land use type,semi-shrubland and shrubland are the main land types affecting ESV.The spatial distribution of ESV based on the 2km×2km grid scale showed that the area of the lower ESV zone generally tended to increase,and the area of the middle ESV zone and the higher ESV zone generally tended to decrease.the sensitivity coefficients of the nine land types ranged from 0 to 0.98,all of which were less than 1,indicating that the estimation of ESV results was good.the ESV showed a strong positive spatial autocorrelation,and the clustering pattern was distributed Clearly,the range of high-value agglomeration areas and low-value agglomeration areas increased.This indicates that the contradiction between ecological land use and high-intensity land resource use leads to regional development imbalance and ecological degradation,and the intensity of human activities should be controlled and environmental management should be strengthened.2.Based on the hydrological cycle elements and VORS model,a new H-VORS model was constructed to evaluate the eco-hydrological synergistic health of the study area.between 1985 and 2021,the eco-hydrological synergistic health status decreased from 0.45to 0.41,basically in a subhealthy state;among the townships,only Ganqiqa and Agoura townships maintained a subhealthy state,while the rest of the townships were in poor health.The hydrological cycle and ecosystem vitality subsystem showed an overall rising trend,the ecosystem organization and restoration showed a decreasing trend,and the ecosystem service capacity showed a decreasing trend followed by a slow rising trend.This study provides important information on the current status of the dune-meadow interphase area,and the study of each system helps to understand the internal change characteristics of the study area,which has a positive effect on improving the health of the ecosystem and helps to optimize the reasonable regulation of the study area.3.Based on the land use change data and health status from 1985 to 2021,ecological sources were identified based on the ecosystem service importance evaluation and ecological sensitivity evaluation,and the ecological security pattern was constructed using the minimum cumulative resistance model(MCR)to analyze the ecological security pattern and its development trends in the study area in five different periods:1985,1995,2005,2015 and 2021,and explore the ecological spatial layout adjustment strategy.The study shows that:(1)the ecological security pattern of the study area has always been small in terms of the area of source land and is relatively scattered,with a low degree of networked ecological corridors and a lack of connectivity between ecological patches;(2)in the past 37 years,the ecological security pattern of the study area has experienced a development trend of deterioration followed by gradual improvement,and ecological policies such as returning farmland to forest and grass and afforestation have significantly improved the environmental security of the study area;(3)The study proposes a zoning policy of"priority protection and simultaneous control",and optimizes the study area by combining the method of arable land suitability evaluation,and the spatial pattern of ecological security pattern shows a"double core-scattered-semi-encircled"system.The results of the study provide a reference for the construction of county-level ecological security pattern in ecologically fragile areas and the ecological management of the horqin sands.From the value of ecosystem services and ecohydrological health of the study area to the construction and optimization of the ecological security pattern,this thesis provides a more comprehensive exploration of the sand dune-meadow interval.The results reveal the spatial and temporal variation characteristics of the indicators within the study area,clarify the spatial and temporal differences between townships,construct an optimization pattern,maintain and regulate the benign relationships within the study area,provide a scientific basis for regional security development planning,and have important guiding significance for the management of the horqin sands. |
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