Study On The Change Of Coastal Wetland Landscape Pattern And Its Response To Main Environmental Factors In The Yellow River Delta In Recent 30 Years

Wetland is an important part of the ecosystem and one of the most important living environments for mankind.The Yellow River Delta is rich in wetland resources,but in recent years,with the development of the economy,the enhancement of human activities and the implementation of relevant policies,wetland resources are seriously threatened.In order to fully grasp the dynamic changes of the wetland landscape pattern in Binhai New Area in recent years.This paper uses Landsat 8 and TM remote sensing images as the main data sources in 1989,1999,2009,2014 and 2018,by useing remote sensing and other techniques to analyze the spatial and temporal evolution of wetland landscape pattern in Binhai New Area in the past 30 years.Based on 91 measured site information,a four-quarter spatial gradient model of vegetation and soil factors was constructed to analyze the spatial distribution characteristics and even relationship of vegetation and soil factors under different landscape types.(1)The Yellow River Delta wetland was seriously degraded,with a total reduction of 893.07 km~2 in the past 30 years,with an average annual reduction of 30.8km~2.The area of natural wetland decreased by 1324 km~2,with the largest decrease in 1999-2009,reaching 614.63km~2;the area of constructed wetland increased by 430.93 km~2,with the largest increase in 2009-2014,which was 124.5 km~2.(2)Farmland and vegetation area are the two largest landscape types in the study area,occupying about 46.87% and 20.6%,while the vegetation coverage contribution rates were 59.07% and 37.62%,the biomass contribution rate were 59.08% and 36.04%.Vegetation and soil factors cause spatial distribution differences of different landscape types in the study area.(3)Vegetation factors show that biomass and vegetation coverage have small seasonal fluctuations in vegetation and bare land,annual average biomass is in medium productivity and low productivity,and annual vegetation coverage is slightly degraded and degraded;Farmland exhibits greater seasonal volatility than other landscape types.The soil factors showed that the annual average available phosphorus(AP)in the coastal wetlands of the Yellow River Delta is in a state of deficiency,which is grade IV standard soil.And the highest annual AP average in the farmland area of the landscape type;The annual average effective potassium(AK)is in a medium state,which is grade IV standard soil.The annual average AK is the highest in the bare land and the lowest in the vegetation area.There was a significant negative correlation between effective potassium and Shannon-wiener index and vegetation coverage in spring and autumn,which became the main controlling factor in plant growth and zeroing.(4)Through the analysis of the landscape pattern index in the study area in 2009,2014 and 2018.The plaque dynamic index was 40.28% in 2009-2018,and the highest in 2011-2018 was 21%.Construction land became the most landscape type with the largest increase in plaques,and the 2018 plaque density index was maintained compared to 2014.stable.The overall change of landscape features the gradual increase of fragmentation,the increasingly complex shape of landscape plaque,the diminishing landscape ecological function,and the balanced development of landscape distribution.