Study On Spatial Distribution Of Land Use Landscape Pattern Under Human Activity Intensity Gradient In Loess Plateau

Under the background of complex and intense human activities,the land use types and ecological environment in the loess plateau have undergone great changes,which are mainly reflected in the change of land use landscape pattern.Therefore,a comprehensive and systematic assessment of land use landscape pattern and its changes under the gradient of human activities is of great significance for ecological construction and sustainable development planning in the loess plateau region..In this study,the loess plateau region as the research area,remote sensing and geographic information system combined,based on the principle of landscape ecology,Landsat 8 OLI satellite image data,DEM data and national basic geographic information database thematic information extraction,through the extraction of land use cover information in 1990,2010 and 2015 analysis of multi-temporal loess plateau land use landscape pattern changes,using the extraction of terrain,roads and settlements three factors to calculate the intensity of human activity,study the loess plateau region of different intensity gradient of human activity under the spatial distribution of land use landscape pattern.The following progress has been made:(1)Land use landscape pattern analysisThe main land use types in the study area are grassland and cultivated land,which occupy more than 60 % of the study area.Due to the implementation of ecological protection policies such as returning farmland to forest and soil and water conservation,the cultivated land was greatly reduced and the forest land and grassland were greatly increased between 1990 and 2015.From 1990 to 2015,with the continuous development of economy,the process of urbanization in the study area has been accelerating,and settlements have increased significantly;During the past 25 years,the water area,surface water amount and unused land area of the loess plateau decreased,and soil and water loss was serious.The landscape types in the study area are relatively stable,but the landscape tends to be fragmented and the landscape heterogeneity increases.That is because the cultivated land area of the study area is converted into construction land and forest and grassland,but the converted construction land and forest and grassland are scattered,and the topography of the study area is broken,the soil and water loss is serious,and the ecological vulnerability is low.With the passage of time,the landscape shape of woodland,shrub,grassland,settlement and unused land tends to be complicated,and the landscape shape of cultivated land tends to be simplified.(2)Analysis of gradient change of land use landscape patternThe gradient of land use types in the loess plateau was significantly different from 1990 to 2015.The dominance of forest land and shrub was linearly related to the intensity of human activity,and decreased with the increase of human activity intensity.Grassland distribution is more uniform in the low to high human activity zone,but not dominant in the high level human activity zone.Cultivated land and settlement showed dominant distribution in the middle-high human activity interval and the least dominant degree in the low human activity interval.Unused land was dominant in the lower intensity range of human activity.At the level of patch type,the patch area and shape index of cultivated land,grassland,forest land and shrub land use types showed the trend of increasing first and decreasing later.The aggregation index of grassland,forest land and shrub increased first and then decreased,and then increased.the aggregation index of cultivated land,water area,settlement and unused land decreased first and then increased.In terms of time,settlement,cultivated land,forest land and grassland were the most seriously affected by human activities from 1990 to 2015.it can be seen that cultivated land,grassland and forest land occupy an absolute dominant position in landscape pattern.Secondly,under the condition of moderate or low intensity of human activities,the percentage of patch area and shape index is larger,the other land use types are at low water level,human activities have a great interference,except shrubs land use landscape type aggregation degree shows a trend of first decrease and then increase.At landscape level,with the enhancement of human activities,Shannon diversity index(SHDI)and Shannon evenness index(SHEI)both showed a downward trend and then upward trend,while contag index(CONTAG)showed a downward trend.In 1990,2010 and 2015,the change trend of land use comprehensive degree was basically consistent with the gradient,which was rising first and then decreasing.Low to medium human activity intensity change is very significant,showing a rapidly rising trend.The change of human activity gradient zone from middle to higher is relatively stable,and the comprehensive degree of land use is significantly reduced after the higher human activity gradient zone.In this paper,the landscape pattern of land use in the loess plateau during the past 25 years is analyzed,and the overall change and the change trend under different human activities interference gradient are analyzed,and significant results are obtained,so as to provide valuable reference for land use policy and sustainable development planning in the study area.