Assessment Of Ecosystem Pattern, Quality, Services And Services Radiation Effect In National Ecological Security Shelters Of Northern China

With the long-term development and utilization and large population growth,especially in the past century,the fragile ecosystem of our country has been seriously degraded,and the supply of ecosystem services is decreasing day by day.In order to cope with the ecological crisis caused by ecological degradation and alleviate the restriction of high-quality economic development due to ecological factors,during the"Eleventh Five-Year Plan"period,our country proposed to build a basic structure of ecological security pattern with a"two screens and three belts"national ecological barrier as the main body.During the"Twelfth Five-Year Plan"period,it is clear that the"two screens and three belts" national ecological barrier will be the main body to build a national ecological security strategic pattern.The construction of a national ecological barrier zone is of great significance for strengthening ecosystem management,improving the quality of the ecological environment,enhancing the ecosystem's ability to provide ecosystem services,and achieving sustainable development.However,due to the large differences in the ecological environment between the north and the east and the east and the west in my country,the reasons for ecological degradation are complicated and the governance is difficult.In addition,due to the lack of early demonstration and planning for the construction of the national ecological barrier,and the unclear mechanism of ecological pattern evolution,there is a lack of research on ecosystem service management.In-depth ecological understanding,ecological information provided for decision-making is still limited.This research relies on the"National Key Research and Development Program"project undertaken by the instructor,uses remote sensing images as the main data source,combines meteorological,soil,hydrological,and socio-economic data,and uses GIS spatial analysis technology.The"Northeast Forest Belt","Northern Sand Control Barrier Belt"and"Loess Plateau Ecological Screen"in the north of the"two screens and three belts"national ecological barrier area are selected as the research objects.Quantitative analysis of the ecological background of the above-mentioned barrier zones from 2005 to 2015 was carried out,and the spatial analysis method of landscape pattern is used to study the temporal and spatial changes of the ecosystem pattern of each barrier zone.The net primary productivity(NPP),leaf area index(LAI),vegetation coverage(FVC)and other indicators are selected to evaluate the quality characteristics and evolution of the ecosystem.The water balance equation,the modified wind erosion equation model(RWEQ)and the universal soil loss equation(USLE)were used to estimate the main ecosystem services of the"Northeast Forest Belt","Northern Sand Prevention Belt"and"Loess Plateau Ecological Screen"respectively.Based on the ecosystem service flow theory,clarify the production-transmission-benefit mechanism of ecosystem services,build a barrier area ecosystem service radiation assessment model,and evaluate the radiation effects of dominant ecosystem services in typical areas of each barrier zone.Based on the research results of radiation assessment,a cross-regional ecological compensation plan is proposed.And comprehensively consider the terrain,the main ecosystem service function and other factors to optimize and adjust the boundary of the current barrier area.The main findings are as follows:(1)From 2005 to 2015,the pattern of ecosystems in each barrier zone was relatively stable,the area of natural ecosystems showed an increasing trend,and the conversion between farmland,forest and grassland was frequent.A large area of farmland has been transferred to grassland and forest,but at the same time grassland,wetland and forest have been converted to farmland to varying degrees;this indicates that the counties involved in the national ecological barrier area have achieved better results in implementing the policy of returning farmland to forest and grassland.However,there is a certain degree of deforestation and land reclamation,and farmland invades other ecological land.Sub-barriers:From2005 to 2015,the desert area in the northern sand defense belt continued to decrease,and a total of about32749km~2 was converted to forest and grass and other types in ten years.In addition,the average patch area of the desert decreases,and the number of patches,shape index,and edge density increased,while the change trend of forests and grasslands was exactly the opposite of that of deserts.Large desert patches were gradually divided into multiple patches by forest and grassland.The transformation of ecosystem types in the past 10 years is positive,indicating that the ecological environment of the northern sand defense belt is developing in a good direction.In the past ten years,the ecological system in the ecological barrier area of the Loess Plateau has changed relatively smoothly,with grassland and farmland dominated.However,the transformation intensity from 2010 to 2015 is negative,and the ecosystem is under certain pressure.The changing trend of the landscape pattern index also supports the above conclusions.Forests are the main ecosystem of the Northeast Forest Belt,accounting for more than 60%of the total area of the Northeast Forest Belt,with little change in the past ten years.The number of patches and patch density in cities and towns increased significantly from 2005 to 2015,indicating that the urbanization process during this period was relatively rapid and the number of cities and towns increased.(2)From 2005 to 2015,the quality of the ecosystems in each barrier zone has been steadily improving,and there is an overall improvement trend,but there is ecological pressure and degradation in local areas.In the northern desert belt,due to the poor natural background conditions,the implementation effect of the ecological restoration project has not been significantly produced.About 72%-80%of the area has a stable state of FVC,NPP and LAI.The FVC in the ecological barrier area of the Loess Plateau increases at a rate of 0.91%and 6.942)/(m~2·(6)per year,which mainly occurs in areas where the FVC is less than 50%.More than 66%of LAI is in a state of improvement,and about 8%of the area is still degraded.Generally speaking,the quality of the ecosystem in the ecological barrier zone of the Loess Plateau has improved significantly.The FVC of the northeast forest belt has improved significantly,with an improved area of 298,800 km~2,and the average FVC in 2015 reached 0.84.LAI has been relatively stable in the past 10 years,and the degraded areas are distributed in dots throughout the barrier belt.However,NPP has decreased at a rate of about 0.842)/(m~2·(6)per year during the decade.(3)From 2005 to 2015,the dominant ecosystem services in each barrier zone showed an increasing trend.The sand-stabilization ecosystem services in the Northern Sand Control Barrier Belt have increased significantly.Over the past decade,the total sand-stabilization ecosystem services have increased by about2.218 billion tons,an increase of 30.47%.However,there are still 69.31%of the areas where the sand-stabilization ecosystem services have remained basically unchanged during the 10 years.At the same time,there are obvious regional differences in spatial distribution,and the amount of sand-stabilization ecosystem services gradually decreases from east to west.The grassland ecosystem is the main body of the sand-stabilization ecosystem services of the Northern Sand Control Barrier Belt.The increase in the amount of sand-stabilization ecosystem services is closely related to the vegetation coverage,and the contribution rate of the vegetation coverage is 44%.In the past ten years,the situation of soil conservation services has improved overall in the ecological barrier area of the Loess Plateau,and forests and grasslands have played an important role in soil conservation.Among them,the growth of forest soil conservation is particularly rapid,increasing at a rate of 22.92 t/(km~2·a).However,local degradation still exists,and the areas with reduced soil conservation are mainly concentrated in the districts and counties on the west side of the Lvliang Mountains-the east side of Huanglong Mountain and the west side of the Ziwu Mountains,covering an area of about 20,900km~2.In the linear regression analysis,the amount of soil conservation is significantly correlated with rainfall and vegetation coverage.The change of vegetation coverage has a small contribution to soil conservation,only 16%.There are obvious differences in the spatial distribution of water conservation services in the Northeast Forest Belt,mainly low-grade,accounting for about 60%,and concentrated in the northern periphery.Among all ecosystem types,forests have the largest water conservation capacity,followed by grasslands.Linear regression analysis shows that the average annual precipitation is significantly positively correlated with water conservation,and the contribution rate to water conservation is the largest,at 79%,while vegetation coverage is not significantly negatively correlated with water conservation.(4)Based on the wind-sand transport process,a radiation assessment model of sand-stabilization ecosystem services was constructed.Based on the law of sediment transport,a radiation assessment model for soil conservation services was constructed.Constructing a water conservation services radiation assessment model based on geographically weighted regression and spatial autocorrelation.Studies in typical areas show that the above models can better simulate the radiation effects of the three ecosystem services,and the radiation effects of ecosystem services in the barrier area are obvious.The ecosystem services provided by the Ordos which located in the Northern Sand Control Barrier Belt provide a significant radiation effect on the sand-stabilization ecosystem services,reducing the amount of dustfall by about2.87×10~8 tons for the beneficiary areas,and avoiding the investment in dust removal by about 4318.51×10~8.The area of the beneficiary area is about 1.66×10~6km~2,which is 19.12 times the area of Ordos,and about 5.08×10~8 people benefited.The beneficiary area of the Loess Plateau Ecological Screen consists of two parts:The Loess Plateau Ecological Screen itself and the lower reaches of the Yellow River.The total population of the beneficiary area is about 0.16×10~8people.Compared with the inside of the barrier zone,the soil conservation services in the Loess Plateau Ecological Screen are of greater significance to the lower Yellow River,reducing the sediment content of the Yellow River and the sedimentation of the lower channel.In terms of radiation effect,the radiation intensity maintained by the soil decreases with the increase of distance.The Northeast Forest Belt mainly radiates the Songhua River basin in China,and the water conservation service benefit area is mainly a small watershed close to the Northeast Forest Belt.There are 272hydrological response units with an area of 8.98×10~4km~2,and the water conservation of about 14.27×10~8m~3 is related to the northeast forest belt.The total population of the beneficiary area is about0.01×10~8 people,accounting for 9.31%of the population of the three eastern provinces.(5)Evaluation based on the radiation effect of ecosystem services can provide new ideas for the formulation of ecological compensation plans,and can more scientifically and reasonably identify the spatial scope of the payment subject,and determine the amount of compensation that should be paid based on the benefit benefits.In the study of typical areas.Taked Ordos(located in the sand prevention belt in the north)as an example.Because Ordos is not only a sand-stabilization ecosystem services providing area,but also the largest beneficiary area of this service.Need to bear about 7.96×10~8 yuan in compensation,accounting for 36.28%of the total ECF,and the remaining 13.99×10~8 yuan will be jointly borne by 16 provinces and cities including Inner Mongolia Autonomous Region and Shaanxi Province.The compensation fee decreases as the distance increases.In view of the existing problems in the timing of the boundary delineation of the ecological barrier zone,the proposed adjustment plan is proposed:The Tarim Sand Control Barrier Belt extends northward to the northern foot of the Tianshan Mountains,and an oasis area in the Tarim Basin is added to the south.The Gansu Corridor Sand Control Barrier Belt extends to the northern edge of the oasis area at the northern foot of the Qilian Mountains.The Inner Mongolia Sand Control Barrier Belt extends to the northern foot of Yinshan Mountain.The ecological barrier zone of the Loess Plateau expands the eastern districts and counties of the Luliang Mountains and adds the eastern end of the Qinling Mountains.The northeast forest belt extends to the south end of Greater Khingan Mountains and the southwest end of Changbai Mountain.Ecosystem management in the barrier area should consider responding to future climate changes,and local climate conditions should be taken into consideration during ecological construction,and measures should be taken in accordance with local conditions.