Dynamic Study On Grassland Resilience In Western Songnen Plain Based On Time Series Remote Sensing Images

The impact of global change on the Earth’s ecosystem is gradually deepening.Grassland is the most widely distributed component of surface cover types and plays an essential role in the stability and development of terrestrial ecosystems.Grassland resilience represents the stability of ecosystems to a certain extent,and climate change and human activities are important influencing factors.The western Songnen Plain is an important area of ecological security in China,and it is also a fragile ecological zone in China.In recent years,with the impact of climate change and human activities,the ecological environment in the western Songnen Plain has undergone significant changes.However,the dynamic change of grassland resilience in the western Songnen Plain and the quantitative contribution of driving factors to the dynamic change of grassland resilience have not been fully studied.It is important to quantitatively distinguish the impact of dynamic changes in grassland resilience among various driving factors for sustainable land management in ecologically fragile areas.Based on the GLASS LAI remote sensing data,land use cover data,and meteorological data of the same period in the study area from 2000 to 2021,this paper constructs a grassland resilience index in the western Songnen Plain using IDL and LAI data as the basic data,studies the dynamic characteristics of grassland resilience in the western Songnen Plain from 2000 to 2021,and analyzes the impact of major climatic factors(temperature,precipitation)on the dynamic change of grassland resilience;At the same time,based on the geographical detector model,the relative contributions of climate factors,human activities,and geographical factors to grassland resilience were further quantified.The main research results and conclusions obtained are as follows:(1)From 2000 to 2021,the grassland area in the study area showed a trend of increasing first and then decreasing,with the total grassland area decreasing by 834.98km~2.In the past 22 years,the centroid of the grassland in the west of Songnen Plain has shown a process of moving first to the southeast and then to the southwest.On the whole,it has moved from the northeast to the southwest,17.95 km to the southwest.(2)From 2000 to 2021,the grassland resilience in the western Songnen Plain was between 0.1 and 0.21,with an average of 0.14 for many years,showing a slight upward trend in the overall fluctuation trend.The 22-year average resilience of grassland in the west of Songnen Plain is characterized by"high and medium value in the north and large distribution of low and medium value in the south".In terms of change trend type,the improved area accounts for 59.09%of the total grassland area,and there is serious degradation in some areas.(3)In the future changes,the grassland resilience in the western part of Songnen Plain is weak and continuous in the same direction.In terms of fluctuation degree,the grassland resilience fluctuates greatly.A small number of areas with continuous degradation are distributed in Lanxi County,Gannan County,Longjiang County and other places,while areas with uncertain future change trend are mainly distributed in the west of Taonan City,Tongyu County,the middle of Changling County,the west of Qiankoerlos,and the west of Zhenlai County.(4)From 2000 to 2021,the annual average temperature in the west of Songnen Plain showed an upward trend,and the rising range of annual average temperature from southeast to northwest gradually increased.The annual average precipitation shows an increasing trend,and the annual precipitation increases gradually from east to west.The response of grassland resilience to temperature and precipitation in the west of Songnen Plain is unevenly distributed in space.In 2000,2005,2010 and 2015,the dominant factors affecting the overall grassland resilience in the study area were temperature and latitude.Climate and geographical location became the main driving factors for the spatial distribution of grassland resilience in the above four periods.In 2020,the main factors affecting the overall grassland resilience in the study area were temperature,precipitation,and population density.Climate and human activities were the main driving forces for the overall grassland resilience distribution in the study area in 2020.