| The rapid economic development is accompanied by the intensification of human activities.Unreasonable land use patterns have changed the landscape pattern and process of the ecosystem,profoundly affecting the long-term security of ecosystem functions and services,which is manifested in the emerging problems,such as the reduction of ecological land,the increased fragmentation of the landscape,the degradation of habitat quality,the reduction of biodiversity,and the reduction of ecosystem service supply capacity.The construction of the ecological security pattern is of great significance for optimizing the allocation of natural resources in the land space,maintaining the stability of the ecosystem,and ensuring regional ecological security by identifying the key components of the security pattern in the landscape to achieve the purpose of regulating and improving important ecological processes.In this context,this study analyzed the characteristics of land use/cover spatio-temporal variations from 2000 to 2018,taking Tongshan County as an example,which is located in low mountain and hilly area of southeastern Hubei and plays a key role in regional ecological security control.On this basis,this study explored the spatio-temporal evolution of habitat quality based on the In VEST model,and revealed the interaction between land use change and habitat quality.In this research both habitat quality and landscape connectivity were taken as the basis for identifying ecological sources.And the minimum cumulative resistance model was used to identifiy the potential ecological corridors.The gravity model was used to distinguish the importance of corridors.Finally,the ecological security pattern of Tongshan County in 2018 was constructed,and this research proposed an optimized scheme for the ecological spatial pattern that in line with the physical geographical features and development needs of the study area.The main conclusions are as follows:(1)The changes in the quantity and structure of land use in Tongshan County from 2000 to 2018 are mainly characterized by the continuous decrease of cultivated land and woodland,and the continuous increase of construction land.The area of grassland and water area first increased and then decreased,and the area of unused land first decreased and then increased.From the perspective of land use dynamic degree,the overall intensity of land use change from 2000 to 2010 was higher than that from 2010 to 2018.Among them construction land changed most dramatically,with the area increasing nearly twice.From the perspective of land use conversion,108.70 km2 and 190.22 km2 of land were converted in 2000-2010 and 2010-2018,respectively.The overall conversion situation is mainly characterized by the conversion of cultivated land to woodland and construction land,the conversion of woodland to cultivated land,grassland and construction land,and the conversion of grassland to woodland.From the perspective of landscape pattern index,Tongshan County’s overall landscape fragmentation degree has deepened,patch shape tends to be more complex,and the dominant landscape in the territory-woodland has good connectivity,and the landscape has a high degree of richness and a high proportionality.(2)The level of habitat degradation in Tongshan County is relatively low,mainly weak and light degradation,showing a slight aggravation trend.The level of habitat quality is relatively high.The average values of the habitat quality index in 2000,2010,and 2018 were 0.781,0.777,and 0.776,respectively,showing a slight deterioration trend.The severely degraded habitats are mainly distributed in the west,south and southeast of Tongshan County where the cultivated land and construction land are concentrated distributed.Habitat quality grades were mainly excellent and good,which accounted for more than 80%of the total area.From 2000 to 2018,the degraded areas of habitat quality were mainly the newly added construction land,and the areas where woodland was converted to cultivated land and grassland.The areas where the habitat quality grade elevated are mainly the areas where cultivated land is converted to woodland and waterland.It can be seen that the main reason for the deterioration of the habitat quality in Tongshan County is the expansion of construction land and the intensification of human activities.The results of the overall Moran’s I analysis showed that the habitat quality of Tongshan County presents a significant spatial clustered distribution,and the degree of clustering was further improved.The results of the hot spot analysis showed that the habitat quality hot spots were located in areas with higher altitude where woodland is concentrated and contiguous.The cold spots were located in areas where cultivated land and construction land are distributed.And the insignificant areas were mainly waterland and grassland.(3)15 ecological sources were identified in this study,with a total area of 738.63 km2,accounting for 30.51%of the total land area of Tongshan County.The land use type of the ecological sources is woodland,and they were mainly distributed in the low mountain and hilly area where altitude is relatively high.The results of ecological security zoning show that high-level ecological buffer zone,medium-level ecological buffer zone and low-level ecological buffer zone account for 23.80%,23.15%and 22.52%of the total area of the study area respectively.This study identified 34 potential ecological corridors with a total length of 236.89 km.Woodland is the main landscape type.The overall layout is consistent with the shape of Tongshan County,forming an "inverted fan";18 important corridors were identified which were low resistance corridors with short distance connecting large habitat patches;27 perching points,10 strategic points,and 34 break points were identified.The ecological network evaluation result showed that the ecological safety network constructed in this study is relatively complex,and each ecological source has a certain degree of connectivity.On this basis,this research puts forward the ecological space optimization scheme of "one barrier,one belt,two districts and five corridors" and suggestions on the protection of ecological security pattern in Tongshan County. |
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