Impact Of Land Use Cover Change On Ecosystem Services In Changbai Mountain Agroforestry Transition Region

Changbai Mountain agriculture and forestry transition area is one of the most important grain producing areas and forest ecosystems in Jilin province.In recent years,due to the traction of national policies,the transformation between land use/cover and cultivated land and forest land has undergone tremendous changes,which has had a significant impact on ecosystem services.In this paper,the Changbai Mountain agroforestry transition area was selected as the research area,and the changes of land use/cover amplitude,speed change,dynamic degree change and landscape pattern of the Changbai Mountain agroforestry transition area for 1988-2016 years were analyzed,and the effects of different land use/cover changes on ecosystem services in the study area were quantitatively evaluated.The main conclusions are as follows:In the 1988-2016 year,the food supply in Changbai Mountain agriculture and forestry transition area showed an upward trend,increasing by 48.78 × 104t.Water production showed a slight upward trend,increasing by 98 million m3.The carbon storage decreased by 1100 x 104t.The habitat quality index showed a downward trend from 0.587 to 0.56.Food supply showed a spatial distribution from south to North and from low to medium to high.The water yield showed a spatial distribution from south to North and from low to high.Carbon storage and habitat quality have similar spatial distribution patterns,showing a high to medium low band distribution pattern from south to north.The transfer of cultivated land and woodland is the reason that led to the change of ecosystem services in Changbai Mountain's agroforestry transitional zone in the past 1988-2016 years.Among them,the main cause of the increase of food supply in the whole region is the transfer between woodland and cultivated land,the construction,land and woodland,the transfer between cultivated land,grassland and woodland,and the transfer of cultivated land,mainly concentrated in Meihekou and Hsien county.The main reason for the loss of carbon storage and habitat quality in the whole area is woodland conversion to farmland and woodland to construction land,mainly in Meihekou and Hui Nan county.The change of cultivated land and woodland is the two main factor leading to the temporal and spatial changes of ecosystem services in Changbai Mountain's agroforestry transitional zone.(1)cultivated land in 1988-2016 years showed an upward trend,rising by 6.17 x 104hm2.The dynamic degree of single land use in Dryland is 1.35%/a,and the comprehensive index of extension degree is 0.98.The dynamic degree of single land use in paddy field is-1.45%/a,and the comprehensive index of expansion degree is 1.03.It shows that the change of cultivated land structure is very fast during this period.From the conversion rate,the paddy field was transferred to the dry land area of 49536.81hm2,with a turnover rate of 43.31%.Dry fields are mainly transferred to construction land and broad-leaved.The total area occupied by construction land was 14566.14hm2,the conversion rate was 5.01%,and the broadleaf forest area was 14143.77hm2 and the conversion rate was 4.95%.From the distance of migration,the core of cultivated land is offset by 8006.46m.The fragmentation index of cultivated land increased,and the paddy field was cut into paddy fields,resulting in the fragmentation of paddy fields,and the shape became more complicated and irregular.The change of cultivated land resulted in the food supply in the whole region.The main factors of the increase of water yield were forestland conversion,construction land transfer and grassland conversion,mainly concentrated in Meihekou and Hsien county.The main factors leading to tihe loss of carbon storage and habitat quality in the whole area are woodland conversion to cultivated land and construction land conversion to farmland,which are mainly concentrated in Meihekou and Hui Nan county.(2)woodland showed a downward trend in the 1988-2016 years,decreasing by 8.31 ×104hm2.The single land use dynamic degree of coniferous forest is 0.63%/a,and the comprehensive index of expansion degree is 0.45.The single land use dynamic degree of broadleaf forest is 0.43%/a,the expansion degree comprehensive index is 0.34,the single land use dynamic degree of the coniferous and broad-leaved mixed forest is 0.22%/a,and the comprehensive index of expansion degree is 0.16.It is said that the change of the forest structure remains relative.Stable.Broad leaved forest was transferred to dry land with an area of 82314.27hm2 and a turnover rate of 12.48%.The coniferous broad-leaved mixed forest was transferred to dry land with an area of 11735.91hm2 and a turnover rate of 20.69%.From the migration distance,the woodland core is offset by 7115m.The number of woodland patches increased,the density of patch increased,the destruction of woodland was increased by 1988-1999 years,and the destruction of broad-leaved forest was enhanced.The management measures for forest land in 1999-2007 years were carried out,and the destruction of broad-leaved forest was slowed down,but the cutting forest was reduced in 2007-2016 years.The fragmentation of broad-leaved forest increased.In the 1988-2016 year,the woodland area of Changbai Mountain's agriculture and forestry transition area showed a downward trend,resulting in a significant decrease in woodland food supply,woodland carbon storage and habitat quality.The main reasons for the increase of water yield are farmland conversion,construction land transfer and grassland conversion,mainly concentrated in Liuhe County and Tonghua county.The main cause of the total area carbon storage and the loss of habitat quality is the conversion of cultivated land to Forestland and the construction of land transfer to forestland,mainly in Meihekou and Tonghua,and in Tonghua.On the whole,the types of ecosystem services show the rule of alienation on the spatial distribution.Mainly because of the thick and fertile soil layer in the northern region of Meihekou,the soil is the main type of land use,and the surface and groundwater resources are relatively rich,which is the main area of food supply.However,due to the influence of agricultural production and other human activities,the quality of the habitat decreased and the carbon storage decreased.The climate of the Liuhe County,Tonghua County,in the central region,is wet and cold,mainly in the mountain forests,with relatively less human disturbance,better vegetation,and greater water production and carbon reserves.In southern Tonghua,the urban landscape ecosystem is disturbed by human activities,and the quality of the habitat decreases and the carbon storage increases gradually.