| As the most core part of the land surface layer,the land system is a complex system of coupling between human society and natural environment,and its changes profoundly affect the circulation process of matter and energy,change the flow of ecosystem services and human well-being,and threaten ecological security.With the increasing human activities,the types and modes of land use have changed greatly,and how to construct a scientific and reasonable model of land system research has become the focus of attention in the fields of land science,landscape ecology,geography and so on.This paper puts forward the"three-pyramid"model of land system research,taking the typical low-mountain mountain area as an example,taking the inner evolution logic as the main line,and taking the space-time scale as the ruler,studies the quantity of the land system,the change of spatial structure,the difference between artificial disturbance and space-time,hydrologic ecological effect,ecosystem service,The ecological security pattern and the future climate scenario land system simulates six blocks of content.In order to provide a scientific and reasonable research idea for land scientists and natural resource planning and management departments.The main findings of this paper are:(1)Based on multi-source remote sensing image interpretation,field sampling,data sharing and other ways to build a large database of land and ecological environment in the research area,spatialized grain production and fertilizer application,and assessed landslides,mudslides and other mountain disasters.The results show that the land use in Qixia City changed dramatically in 2000-2010,mainly for the transfer of cultivated land to construction land,and the change slowed in 2010-2015;15 years of cultivated land reduces 5485.70 hm~2,construction land increases 5232.15 hm~2;Food production has decreased sharply and fertilizer use has increased significantly.The change sensing characteristics of land use type and structure in quantity and spatial distribution,as well as natural ecological changes such as climate,soil and vegetation,and the change of natural ecological changes in climate,soil and vegetation in Qixia City from 2000 to 2015 are basically undertaken,and as a pattern exploration module for the study of land system,the value assessment of the service of regional ecosystems is noted.Sub-modules of land system research such as ecological security pattern construction and future land system space simulation provide basic data support.(2)Distribution index is used to study the distribution characteristics of land use types under the topographical gradients of the study area,such as elevation,terrain uplift,slope direction and slope variability,and the changes of land use types under different topographic factors from 2000 to 2015.The study found that the low terrain gradient is the main gradient area of the distribution and change of land use type in Qixia City.This part of the study as a sub-module of the pattern detection module of land systemization research is an effective complement to the study of typical regional land system,which can reflect the characteristics of regional land change,and provide decision support for the region to rationalize and intensively utilize under low-terrain gradient and protect the fragile ecological environment of mountain areas.(3)Using the method of area information conservation and particle size resampling,the best analysis granularscale scale of landscape pattern in the study area is 30m determined by the landscape index curve fitting inflection point,and the best analysis scale of the study area is 1500m determined by the moving windows method and the semivariogram analysis,and the characteristic scale of the study area is determined by the comprehensive granularity and magnitude.The human interference index of the study area is constructed by grid sampling,and the spatial aggregation and separation characteristics of human interference and the change sit-in condition sittinin in the 15 years from 2000 to 2015 are discussed from the aspects of global self-correlation and local self-correlation.To set up different buffer zone sample belts as the center of the town,and analyze the spatial and temporal evolution of landscape patterns in the four aspects of artificial interference landscape in the buffer radius of different towns,pattern structure,aggregation and diversity,on the characteristic scale.The results show that with the increase of the distance in the center of town,the artificial interference gradually weakens,the distance threshold of landscape fragmentation under human interference in Qixia City is 10000m,the distance threshold of aggregation is 6000m,and the distance threshold of diversity is 4000m.The"human-land"relationship coupling has its own characteristics in the research area,which,as another sub-module of the land system pattern detection module,basically understands the extent and scope of the influence of human activities on the land system in the research area by using landscape ecology and land remote coupling theory.(4)Taking the total national generating value,population density,grain production and fertilizer usage changes as economic and social drivers,with elevation difference,precipitation,temperature,vegetation net first productivity,soil erosion as the natural driving factor,to study the dynamics of land change,arable land change dynamics,construction land dynamics as the factor variables,The two driving methods of"social-natural"binary driven with common least-multiplier and geo-weighted regression that do not consider spatial heterogeneity under the small watershed scale based on DEM division find that the geographically weighted regression model is superior to the common minimum multiplication model,and the drivers are:terrain,gross national product,Population density,grain production and the comprehensive dynamics of land use and dynamic changes in cultivated land and construction land are closely related,and there are significant spatial difference severance laws in the factors of comprehensive dynamics of land use and change of cultivated land in the study area.At the same time,according to the regional characteristics,the key research on the driving forces of the drastic land use type of change provides a certain basis for the rational allocation of the whole elements of sustainable use of the regional land system.(5)The circulation of hydrologic substances such as runoff,sediment content,organic nitrogen,organophosphorus and nitrate content entering the main river channel at different scales at different stages of Qixia City was simulated by the distributed hydrological model SWAT model.Using SWAT-CUP,the field monitoring data and simulation data fit results are verified by using the decision coefficient and nash coefficient,the reasonableness of the model parameters is determined,the uncertainty of the model is reduced,and the accuracy of the simulation results is guaranteed.The characteristics of different small basin landscape patterns and hydrologic substance distribution are analyzed by the analysis method of the non-constrained main component,and the correlation between precipitation and runoff,sediment and nutrients entering the main river channel,land use change and runoff,It is found that forest land is the"sink"type of water quality pollution,and cultivated land and construction land are the"source"type of water quality pollution.The correlation of sediment content to nutrients,drawing on the corresponding model analysis(CCA)and path analysis in ecology,the correlation between landscape pattern index and water quality under the small watershed scale was studied,and found that the spot was different on the scale of the spot,and the block was different in its effect on the retention and promotion of pollutants.Under the landscape level the plaque density and shape in both scales to intercept effects of all kinds of water pollution,plaque spread degree is different,the effect of different scales and landscape diversity in small watershed scale effect is not obvious.This part of the study is a study of the coupling between land use/landscape pattern and ecological process,is the land change effect module in the study of land system,taking the hydroecological effect of land system change in the study area as an example,and in-depth lying about the relationship between the"pattern and process"of the study area by means of model and quantitative method.It provides an effective solution path for the ecological environment protection in the low hilly area of Ludong from the perspective of land.(6)On the basis of the exploration of land system pattern change and ecological effects,Using Xie's proposed method of ecosystem service evaluation value and revision method,we use ground data and Google historical images to subdivide land use types using the ecosystem service value assessment scale,using vegetation net first productivity,Precipitation and soil retention revise ecosystem service value equivalent factors,take inflation and other factors into the discount rate correction factor,quantitativeand spatial evaluation of ecosystem service value under the grid scale of the study area,sensitive analysis of ecosystem service value,Among the single services,climate regulation,hydrologic regulation and soil conservation accounted for 60.70 percent and 61.54 percent of the total value,respectively,in 2000 and2015,and were key ecosystem service types in the city of Qixia.The total value of ecosystem services increased by 1.74 per cent in 15 years,but the value of food supply fell the most,to4.51 per cent,and the value of water supply increased the most,by 7.54 per cent..Based on global spatial self-correlation,Local spatial self-correlation and the use of simple kriging interpolation and other exploratory spatial analysis methods to study the 15 years of ecosystem value space-time separation characteristics in Qixia City from 2000 to 2015.It was found that the spatial scale dependence of ecosystem service value was weakened and the cold point area increased.This part of the study is an extension of the ecological effect module in the study of land system,and it is also the basis of regional ecological security pattern and future land system spatial simulation research based on ecological security pattern.(7)Based on the spatial distribution characteristics of different ecosystem services,different levels of ecosystem service important areas are divided according to the aggregation of each service function,and a comprehensive ecological security pattern is constructed.Using artificial neural network algorithm to obtain the adaptive probability of land use change in the study area by using the natural and social driving factor data as the training data.With the minimum level area of ecological security pattern as the restricted development area,the decision-making unit of multi-intelligent body is constructed,in which the decision-making objective of the control body uses the amount of land use change under the Markov module climate scenario of TerrSet,guides the subject to adopt the corresponding local class of ecological security pattern partition,and implements the main body adopts adaptive degree operator.Based on roulette selection mechanism,the cell automaton model simulates the spatial distribution of land use in 2010,The verification results show that the model has high accuracy for water area and construction land simulation,,kappa coefficient were above90%.predicts the quantity of land use change under the RCP 4.5 concentration path,and simulates the land use spatial change in 2030,2050,2070 and 2100,Restricted by the pattern of ecological security,the water area and construction land will not change much in the next80 years,the area of cultivated land will increase significantly,and other land such as garden land will decrease significantly.To simulate the future of the change of land system space,on the basis of analyzing the future hydrological ecological environment risk,the results show that water quality improved significantly in the study area,soil loss significantly reduced.As the final module of land systematic research,it is not only an effective way to test the optimization effect of"pattern-process"from the perspective of ecological protection,and it can be used as a reference for the sustainable use of land in the research area.Starting from the view of system and sustainable development,this study deepens and perfects the theoretical method and technical system of land system utilization and protection in the typical low hilly hilly area,effectively solves the bottleneck of economic development and ecological protection in low hilly area,and breaks through the difficult problems brought about by the lack of regional historical data.The scientific and reasonable prediction of land space allocation and ecological environment provides reliable technical support for the harmonious development of"climate-land-human"in the research area. |
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