Impacts Of Land Use Change On Habitat Quality In The Upper Reaches Of The Fen River

Land use change is the main driving force of regional ecological environment change.With the deepening of urbanization,the relationship between land use and ecological environment has been paid more and more attention.The upper reaches of Fenhe River is an ecologically fragile area of the Loess Plateau.In recent years,due to the unreasonable land use caused by human activities,the ecological environment is deteriorating day by day.It is of great practical significance for sustainable development of the upper Fen River to analyze the land use change and the temporal and spatial variation of habitat quality in the upper Fen River in the past 20 years,explore the influencing factors and reveal the influence of land use change on habitat quality in the upper Fen River.This paper takes the upper reaches of Fen River as the research object,using remote sensing images of Fen River in 2000,2010 and 2020 as data sources,and using land use transfer matrix and other methods to analyze the spatio-temporal characteristics of land use change.Habitat degradation degree and Habitat Quality were analyzed and evaluated based on the habitat quality module of In VEST model.The influencing factors of habitat quality were detected by using geographic detector,and then the influence of land use change on habitat quality was discussed.The main research conclusions are as follows:(1)From 2000 to 2020,the cultivated land,forest land and grassland in the upper reaches of Fenhe River accounted for 97%.The area of cultivated land,grassland,forest land and water area decreased,while the area of construction land increased;The land with the highest rate of change is unused land,followed by construction land.The comprehensive index of land use degree in the upper reaches of Fenhe River shows an upward trend and is in the developing period.In terms of space,the area of construction land increased significantly and showed a multi-point diffusion distribution along the river valley.From 2000 to 2010,the trend of diffusion was obvious in the central and western part of China and the southeast part of China,but there was little change during 2010 to2020.In the upper reaches of Fenhe River,land use transfer changes mainly include cultivated land,forest land and grassland to construction land.(2)From 2000 to 2020,the upper reaches of Fenhe River was at a moderate degradation level,and the degradation speed was faster from 2000 to 2010,and it was obviously improved from 2010 to 2020.With the passage of time,the area of highly degraded and severely degraded increased,while the area of mildly degraded and moderately degraded decreased.Spatially,different levels of habitat degradation decreased from the center to the outside.(3)The habitat quality index in the upper reaches of Fenhe River was in the range of0.4-0.6,which was a general level,and showed a decreasing trend with time.The lower level was the main habitat quality type in the study area,which decreased rapidly during2000-2010 and improved during 2010-2020.In spatial distribution,the quality of habitat increased from the center to the surrounding area.In the upper reaches of Fenhe River,89.78% of habitat quality grades remained unchanged,and 8.01% of habitat quality grades decreased.The decreased habitat quality grades were mainly from higher grade to lower grade.2.21% grade elevation,of which the lower to general conversion area is the most.From 2010 to 2020,the habitat quality grade shifted steadily,and the proportion of habitat quality deterioration area decreased significantly.(4)The explanatory power of influencing factors on habitat quality in descending order was land use > elevation > annual average precipitation >GDP> slope >temperature >NDVI> population density.The interpretation of land use was the highest,which was 0.5826.The interaction detection results showed that the two factors were enhanced,and the interaction between land use and other factors was obvious.There was a negative correlation between the comprehensive index of land use and the habitat quality,and the local spatial correlation was low-high type and high-low type.High-low types were mainly distributed in the middle of the study area,while low-high types were mainly distributed in the periphery of the study area.The effect of land use transfer on habitat quality was worse than better.The conversion of cultivated land,forest land and grassland to construction land had negative effects on habitat quality,and the conversion of forest land and grassland to cultivated land had the most negative effects.The conversion of cultivated land to grassland and woodland had positive effects on regional habitat.The negative effect was much greater than the positive effect during 2000-2010,and the negative effect was smaller during 2010-2020.Compared with 2000-2010,the land use structure change from 2010 to 2020 showed a uniform and dense distribution in space,and the land use pattern was obviously optimized,resulting in a smaller habitat quality change value.Land use structure change under the influence of human activities destroys and protects ecology simultaneously.