Study On Land Use/Cover Change And Its Eco-Environmental Effects In Fujiang Basin

The paper explores the impact of spatial and temporal distribution of land use/cover on the ecological environment in the Fujiang basin.This paper analyses the change of Spatial distribution,amount and landscape patterns of land use/cover by ArcGIS,ENVI,GEE.Finally,the ecological environment effects of land use change are analyzed by estimation of net primary productivity,soil erosion and ecological environment quality in the Fujiang basin.The paper is helpful to provide scientific basis for the rational use of land and ecological environment protection in the study area,and also to enrich the case of land use/cover research at regional scale,and provide some reference for other similar areas.Main conclusions are as follows:?1?The land reclamation rate between 38.22%and 43.50%,and the grassland index between 29.32%and 35.98%in the Fujiang basin.The urban land area increased by 58.56%,the wetland area increased by 41.26%and the grassland land area decreased by-18.51%.Between 2002 and 2017,the dynamic of urban land use was 3.90%per year,which is the highest land use dynamics in the Fujiang basin.Wetland land use dynamics was second,it increasing by 2.75%per year.The dynamic degree of grassland was-1.23%/per year.In the basin,there was 3,657.59 km² of grassland land to converted into farmland land,1764.44 km²of farmland land was converted into grassland land,931.65 km² of grassland land was converted into forest land,400.97 km² of forest land was converted into grassland land,and144.23 km² of farmland land was converted to urban land,63.81 km² of grassland land converted to urban land.The overall land use conversion is relatively strong,with a dynamic degree of 1.93%in the Fujiang basin.?2?Overall,the landscape diversity index of land types tends to be abundant and increasing.The scattered small patches of landscape patches are increasing,and the aggregated large patches are increasing.From the point of view of type landscape,the fragmentation of grassland is the highest,and the geometric shape of patches is the most complex.The largest dominant patch is farmland in the study basin.Forest land,wetland and town have the highest dispersion index,which indicates that the three types of land use patches are large and scattered.Forest land,wetland and urban have the highest dispersion index,which indicates that the three types of land use patches are large and scattered.In a word,with the passage of time,various landscapes showed different characteristics under the influence of natural and human activities in the study basin.?3?The net primary productivity of vegetation in the southern part of the Fujing basin was lower than that in the north,The NPP was lower in Midstream and downstream areas of Fujing basin.The NPP was higher in Upstream area of Fujing basin.The value of forest NPP was the largest,and it was 505.25gCm^-2a^-1.The value of wetland NPP was the least and it was196.48 gCm^-2a^-1.In the Fujing basin,60.27%of the region was growing,39.73%of the region was negative growth.The overall NPP change was negative,with a slope of-0.12.The slope of NPP change of wetland and farmland land was 0.28.The slope of the woodland NPP change was-0.08.?4?The main characteristics of soil erosion are micro-erosion and mild erosion in the Fujing basin.The micro-erosion area accounts for 39.68%-71.55%,and the mild erosion area accounts for 16.77%-38.55%.The area of extremely strong erosion was between 0.86%and2.51%,and the area of severe erosion was between 0.88%and 2.81%.In the basin,soil erosion has been reduced year by year,it was reduced from 3.4×10³ T/hm² a in 2002 to 1.4×10³ T/hm²a in 2017.The amount of soil erosion converted from farmland to grassland has increased.The total amount of soil erosion converted from farmland to grassland increased by 0.53×10⁷ T,and the average value increased by 0.75×10³ T/hm² a.The total amount of soil erosion converted from grassland to farmland was reduced by-5.32×10⁷ T.The average soil erosion from grassland to town was reduced by 16.5×10³ T/hm² a.?5?In the Fujing basin,the natural ecological environment of the good level was the largest,it accounting for 51.00%-75.18%of the total area.the poor level was the largest,it accounting for 2.56%-3.84%of the total area.Compared with 2002,the area of poor level and the average level decreased by 1.28%and 35.07%respectively in 2017,the area of good level and the excellent level increased by 24.58%and 11.77%respectively.The area of excellent level ecological environment quality was largest in Beichuan County and Pingwu County.The area of excellent level ecological environment quality was least in Yinan County and Xichong County.