| Land Use and Cover Change(LUCC)is a cross scientific research topic,which is collaborated by International Geosphere-biosphere Programme(IGBP)and International Human Dimensions Programme on Global Environmental Change(IHDP),however,as to fulfill the human needs,the land resources and transformation continued to increase,which led the loss of regional soil and water,land desertification,salinization,vegetation degradation and other environmental problems.It not only affects the structure and function of ecosystem succession directly,but also cause serious damage to regional ecological security pattern.Little Sanjiang plain is located in the core area of Sanjiang plain,which is the main marsh area of China.With the population surge,the ascension of agricultural modernization of technology and the interference of human activities for more than 50 years,it has become to the "Great Northern Warehouse" instead of "Great Northern Wilderness",and also is the important commodity grain production bases of China,meanwhile,it has caused many ecological environment problems.In this paper,with reference of relevant research,we used Landsat/MSS,TM remote sensing image as the main information source,with the support of RS and GIS,land use change model,map information model and landscape pattern analysis of land use from 1976 to 2013 in the study area were used to study the space-time evolution characteristics and spatial change of landscape pattern and ecological process.Based on the driving factors such as the natural environment and social economic,the internal driving mechanism of land use landscape pattern evolution was discussed.The theory of "pattern-process-effect" in landscape ecology were used to construct the landscape ecological security evaluation model based on the landscape level,in terms of natural resource state,environmental ecological pressure and natural-environmental response.So as to explore the ways of ecological recovery measures,also,to provide technical support and theoretical basis for regional ecological restoration and protection,eco-environmental reconstruction.The results showed that.1)During 1976 to 2013,great changes have taken place in Little Sanjiang plain.The land use pattern transformed from natural mixed landscape,such as wetland and other natural landscape,into a regional pattern dominated by man-made landscape,the structure of regional land structure was increasingly unreasonable.Among which,the land use structure was dominated by natural landscape(unused land,grassland and forest land)in 1976,accounted for 68.28%.The proportion of natural landscape in 2000 and 2013 was 38.20%and 19.62%respectively,and the proportion of man-made landscape(arable land and residential land)reached 51.99%and 78.19%respectively.The arable land,forest land and residential areas in the study area increased,and the grassland,unused land and water area decreased,as well as the grassland closed to the extreme decline trend.2)In the 37 years,the land use composite index increased from 188.39 in 1976 to 269.12 in 2013,and showed an increasing trend in each administrative unit,but the value was relatively small of the reserves in the three periods,this is mainly due to of large-scale development and continuous small-scale farming activities.The initial change type was the largest map unit in the research area,with the ratio of 36.92%,and the largest map type was"unutilized land-arable land-arable land",which accounted for 50.75%of the variation pattern of this type.The minimum mapping unit type was repeatedly changed type,accounting for 6.55%of the total area,arable land-forest land-arable land was the most large area map mode,and the late change type was "unused land-unused land-arable land".Continuous change type was"unused land-forest land-arable land".3)The patch number of arable land and forest land increased firstly and then decreased,grassland,water area and unused land presented a continuing decreasing trend,and the residents of mining land showed an increasing trend.The biggest patch perimeter,area and the average patch area,perimeter of forest land,grassland,unused land and arable land have good positive correlation,but the forest land,grassland and unused land landscape showed a trend of decrease,and the farmland showed an increasing trend.The number of plaques presented complex changes with the increase of particle size.The aggregation degree and fractal dimension of landscape patches appeared regular changes with the increase of particle size.The aggregation degree showed linear decreasing trend with the increasing of particle increasing,and the distribution and parallel index showed linear increasing trend.The diversity of landscape and evenness index did not showed the obvious particle size effect.4)During the 37 years,diversity index and evenness index decreased from 1.3488 and 0.7528 of 1976 to 0.7928 and 0.4436 of 2013 in the study area,landscape dominance index increased from 1.2362 of 1976 to 1.7922 of 2013.It showed that each landscape component distribution trend was uneven,the difference of area ratio increased and the homogeneous degree reduced,landscape pattern was strengthened by one or several dominant landscape types.The dominant landscape type enhances the overall control of the landscape,and the integrality of landscape was well.In the study area,it showed that the arable land was the substrate,and unused land,forest land,grassland,water area and residents of mining land dot the landscape as the patches,which related to the natural conditions,economic development level and the regional industrial structure.5)During the 37 years,the arable land had a high transfer contribution rate,which accounted 55.34%and 80.50%in 1976-2000 and 2000-2013 respectively,and the ratio of the contribution rate was higher than that of the transferred contribution rate.The contribution rate of the residential area was higher than the contribution rate.The contribution rate of water,grassland and unutilized landscape was higher than the transfer contribution rate.The contribution rates of forest land-arable land,grassland-arable land and unused land-arable land were 30.50%,1.86%and 47.28%respectively in 1976-2000.Arable land,forest land and water landscapes had higher retention rate,while grassland and unused land had lower retention rate,the retention rate of arable land landscape in 2000-2013 was the largest,94.85%,and the smallest was the grass landscape,which was only 0.59%.The change mode of forest land--arable land,grassland-arable land and unused land-arable land basically reflect the dominant driving factors of dynamic change of landscape composition.6)The value of ecological services in the study area decreased from 2242.91 x 107 yuan in 1976 to 1280.95 x 107 yuan in 2013,and the annual rate of reduction was 1.15%.The ecological service value of arable land and residents of mining land showed an increasing trend.Farmland landscape ecological service value increased from 228.770 x 107 yuan in 1976 to 615.815 x 107 yuan in 2013,while unused land,grassland and water landscape presented a downward trend,and the value of landscape ecosystem services of unused land has declined the most which was 1213.131 x 1.07 million yuan,the grassland landscape was 173.541 x 107 yuan.Unused(wetland)as the main body of ecological value in 1976 and 2000,the ecosystem service value was 72.071%and 53.763%respectively.Farmland was the main body,which had a ratio of 48.075%in 2013.Which due to the landscape pattern changed from the mixed landscape pattern of the original wetland matrix to the agricultural landscape pattern of the current farmland matrix,presented a wetland domain landscape types of natural ecosystem environment into farmland as the main landscape types of half natural ecosystem environment.7)Based on landscape ecology "pattern-process-effect "theory,under GIS and spatial autocorrelation as well as other technical support,from the state of natural resources,environmental and ecological pressure and response on nature and environment,landscape ecological security evaluation model was constructed based on the landscape level,landscape pattern of temporal and spatial evolution and the response to the inner mechanism of the regional ecol-process,the three phase of landscape ecological security of global Moran's I index was positive,which indicated a greater space landscape ecological security integration,and its spatial distribution was not random,there existed a high-high and low-low positive correlation,and a low-high or high-low space negative correlation.The high-high autocorrelation type mainly distributed in ecological security level V in 1976,and high-high distributed in river and protected area,high-high concentrated area and low-low concentrated area showed an obvious spatial differentiation characteristics in 2000 and 2013.Landscape ecological security presented conversion characteristics from high level to middle and low level in 1976-2013.The ecological security level was mainly ? and ? in 1976,covered an area of 62.36%,while the level ? and IV occupied a large proportion in 2000,accounting for 54.13%of the total area,and level ? and ? occupied the dominant position in 2013,which took up to 68.34%.8)Landscape ecological environment security assessment is always a difficult problem to ecological security research,based on the field investigation and quantitative remote sensing inversion of vegetation coverage data,we established the regression relationship between ecological safety and regional environment,it showed that the landscape ecological security and vegetation coverage presented a high positive correlation,the correlation coefficient R2 was 0.9028.For better reveal the vegetation coverage change relationship between value and landscape ecological security changes,we used the change value of 1976-2000 and 2000-2013 to establish the regression model,the correlation coefficient R2 was 0.9577 and 0.9577,respectively,and they were higher than 0.9028,which showed that landscape ecological security and the vegetation coverage changes also has high relevance,and landscape ecological security can well reflect the regional ecological environment change information and the ecological environment quality condition.9)Markov model was used to forecast the result of landscape ecological security in the study area,and the simulation results showed that ecological security level ? ratio appeared an increasing trend from 2013 to the final balance condition,and other ecological area ratio showed a decreasing trend,ecological security level ? ratio in the equilibrium state was 72.64%,which had the absolute advantage position,and then was ecological security level ?,the ratio was 20.54%,and ecological security level V was the minimum,accounted for only 1.10%.The final simulation results were similar to the results of 2013,presented an absolute advantage of ecological security ? and ?,while other ecological levels were in a secondary dominant position. |
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