Study On The Construction Of Ecological Security Pattern In Hehuang Region

With the development of society and economy,the population gradually migrates to the cities and the progress of urbanization in China has made remarkable achievements.However,with the progress of urbanization,human activities have unreasonably exploited and utilized the national and regional space,leading to the gradual deterioration of the ecological environment in the region.Faced with the ever-increasing ecological environment,the state put forward the general idea of ecological civilization construction at the 18 th National Congress of the Communist Party of China,and constructed the regional ecological security pattern as an important part of ecological civilization construction.It has now risen to the national security strategic level.At the same time,in order to comply with the law of urbanization,the state has formulated a new urbanization development plan.Urban agglomeration,as the starting point for a new type of urbanization planning,plays an important role in promoting regional coordinated development and nurturing the regional growth pole.However,the development of urban agglomeration depends on the regional carrying capacity of resources and environment.Only by rationally allocating resources and environmental capacity and scientifically constructing the regional ecological security pattern can the relationship between land development and ecological and environmental protection be properly handled.The Hehuang area is located between the ecological barrier of the Qinghai-Tibet Plateau and the sand control belt in the north of our country.It has a unique strategic support to protect the "China Water Tower" and prevent the westward desertification from spreading eastwards.It is also dominated by "two screens and three belts" National ecological security strategy is closely related to the pattern of bearing the ecological protection of the region has an important role.However,the natural environmental conditions in the region itself determine the ecological environment in the region is very fragile.With the unreasonable development and utilization ofhuman activities,serious soil erosion,expansion of land desertification,frequent geological disasters and biodiversity reduction,Prominent environmental issues.With the advancing of new national urbanization,Hehuang area,as an important bearing area of Lanzhou-Xining urban agglomeration,is especially necessary to construct the ecological security pattern in this area.Based on this,based on combing the theory of ecological security and the research progress at home and abroad,this paper uses the dynamic changes of land use,land use transfer matrix,landscape pattern index,water balance model,modified generalized soil loss equation and INVEST model,Cumulative resistance model and other research methods to build regional ecological security pattern.By analyzing the evolution of land use and the characteristics of landscape pattern in the past 20 years,the characteristics of regional eco-environment are known.By assessing the importance of ecosystem function,the spatial distribution of important eco-functions in the region is mastered,which will lay the foundation for identifying key ecological sources in the study area Based on the model of minimum cumulative resistance,the minimum cumulative resistance surface of the study area was established,and finally the regional ecological security pattern composed of ecological sources,ecological buffer zones,ecological corridors and ecological strategic nodes was constructed.Conclusion as below:(1)The evolution of land use in Hehuang area: The land use types in Hehuang area are mainly agriculture,mainly cultivated land,woodland and grassland,accounting for more than 80% of the total area of the study area.Through comparison of two 10 years before and after,we can find that the rate of land use change is gradually accelerating,and the rate of change after the last 10 years is 1.61 times of the former.Among them,there are construction land,cultivated land,woodland and unutilized land where the rate of change is accelerated;grassland and water area where the rate of change is slowing down.The increase of construction land in thelater 10 years is 6.7 times that of the previous ten years,mainly taking up farmland and grassland,mainly distributed in Lanzhou,Baiyin,Xining and Haidong.The cultivated land area is in a decreasing trend as a whole,mainly occupied by construction,converted to grassland after returning farmland to forest and abandoned farmland.The area of forestland is increasing as a whole,mainly from cultivated land and grassland.The area of grassland continues to decrease,which is mainly converted into cultivated land and construction land;The area of water fluctuated before and after the change,basically the same,mainly converted into forest land and construction land;the unutilized land gradually decreased and mainly converted into cultivated land,woodland and grassland.(2)Landscape characteristics of Hehuang area: From 1995 to 2015,under the pressure of human social and economic activities,the spatial distribution of landscape types in Hehuang area tends to be scattered,the degree of aggregation is reduced,the landscape is more fragmented and complicated,and the dominance of single landscape type Reduce the diversity of landscapes.With the implementation of the policy of returning the grain plots to forestry,the degree of fragmentation of forest landscape gradually decreases,the shape is more regular and the connectivity is improved.The cultivated land,grassland and unutilized landscape Degree of fragmentation gradually increased,complex shape,connectivity decreased;changes in the water is not obvious.Based on the above research results,it can be found that human activities are constantly changing the land use in the Hehuang area,and thus the impact on the natural ecology is gradually increasing.(3)The importance of ecosystem function in Hehuang area: After evaluation,the functional importance of Hexi area is divided into four types: high,medium,low,medium and low,accounting for 21.78%,18.73% and 35.62%,23.87%.Areas of high importance are mainly concentrated in the southern and northwestern parts of the Hehuang area,with the southern part being dominated by Gannan TibetanAutonomous Prefecture and Huangnan Tibetan Autonomous Prefecture,and the Qilian Mountains and Qinghai Lake in the northwest as the main body.The areas of low importance are mainly located in the northeast and southwest,while the northeast mainly concentrates in the areas of Lanzhou,Baiyin,Dingxi and the northern part of Linxia Hui Autonomous Prefecture,Xining and Haidong;Focus on the Central Tibetan Basin in Hainan Tibetan Autonomous Prefecture.According to the assessment of the functional importance of single ecosystem,the four levels of importance can be divided into four types,and the spatial distribution results are basically the same,that is,the regions with high function of ecosystem are basically distributed in Hehuang area The less important areas in the south and northwest are generally distributed in the north-east and south-west.In terms of scale and structure,carbon fixation and oxygen release accounts for 25.42%,23.60%,20.38% and 30.60% of the study area respectively;water conservation accounts for 21.20%,28.04%,32.07% and 18.70%of the studied area;14.38%,16.03%,33.88% and 35.71%,respectively.Biodiversity accounted for 19.48%,8.67%,53.68% and 18.17% of the study area.(4)Identification of important ecological sources in Hehuang area: Based on the evaluation of ecosystem function importance,Hexiu area's major ecological sources were identified.The provenance of important ecosystem services in the area accounted for 40.51% of the total area of the study area.Surrounded by the southern and northwestern parts of the study area,the southern part is mainly centered on Gannan Tibetan Autonomous Prefecture and Huangnan Tibetan Autonomous Prefecture,and the Qinghai Lake and Qilian Mountain as the center in the northwest.The land is dominated by forest land,water area and grassland.(5)Construction of Ecological Security Pattern in Hehuang Areas: The basic resistance surface is set from the perspective of topographic factors and land cover types,and the minimum cumulative resistance surface is used to construct the minimum cumulative resistance surface of the study area.According to the frequencydistribution curve of resistance value,the minimum cumulative resistance surface is divided into three types of high,medium and low safety levels of ecological safety pattern,accounting for 14.46%,13.71%,31.32% respectively of the study area,The areas with low level of ecological security should be given priority to be protected.Urban construction and agricultural development should give priority to the use of areas with high ecological security.Through the analysis of the shortest path and the hydrological analysis of the flow between the ecological sources on the minimum cumulative resistance surface,a total of 57 ecological corridors and 37 ecological strategic nodes were identified in the study area.In the future ecological engineering construction,we should focus on strengthening the ecology Corridor construction,especially ecological corridors in the very fragile ecological strategy node.