Identification Of Black Soil Arable Land In Songnen Plain Of Heilongjiang Province Based On Remote Sensing Evaluation Of Soil Erosion

Heilongjiang Province is an important commodity grain base in my country.It is located in one of the three remaining black soil belts in the world,and its cultivated land area ranks first in the country.The study area is located in the black soil core area of the Songnen Plain in Heilongjiang Province,with a total area of 15.78×104km2,of which arable land is 8.81×104km2,including Harbin(partial),Qiqihar,Daqing,Suihua,Heihe(partial)5 prefecture-level administrative regions,33 cities and counties.The zonal soils in this area are mainly black soil and chernozem,which are suitable for cultivating and have superior natural endowments.However,unreasonable development and utilization for a long time and excessive acquisition have caused serious degradation of the physical and chemical properties and ecological functions of black soil.The "ecological function zone" has been transformed into an "ecologically fragile zone",and soil erosion has become a prominent constraint on the sustainable development of agriculture in this area.This research adopts remote sensing and informatization methods,with the help of large-scale,high-temporal-resolution remote sensing data and soil erosion model identification technology,and combines and superimposes with DEM data,land use,administrative division,elevation zoning,and soil classification vector data to create Generated a geospatial data set of cultivated land soil erosion in the black soil area,revealing the occurrence,growth and decline trends and spatial differentiation pattern of soil erosion in the black soil cultivated land in the Songnen Plain of Heilongjiang Province,implementing black soil protection in our province,maintaining the red line of cultivated land,and carrying out cultivated land water and soil conservation Monitoring provides basic support.It provides a scientific basis for evaluating the effects of soil erosion control,optimizing the layout of water and soil conservation projects,and consolidating the results of soil erosion control.1.Clarify the background and current distribution of black soil cultivated land in Songnen Plain,Heilongjiang Province.Based on remote sensing identification and GIS analysis,in 2000,the background area of black soil cultivated land in Songnen Plain of Heilongjiang Province was 79560.58km2,and the background area of cultivated soil erosion was 39758.59km2?accounting for 50%of the total cultivated area.The total annual erosion of cultivated land can reach 4680×104t/a,which is equivalent to an annual loss of 15600hm2 cultivated land.The current arable land area in the black soil area in 2019 is 88050.56km2,accounting for 55.8%of the total area of the region.According to the classification of the slope,the cultivated land in the black soil area<0.25°accounts for 69.3%of the cultivated land area,and the cultivated land>15° accounts for 0.01%of the cultivated land area.Divided by elevation zone,black soil cultivated land is mainly distributed between 100-200m above sea level in the central Songnen Plain,accounting for 55.1%of the total cultivated area.Divided by soil type,the main zonal soil of the cultivated land in the black soil area is black soil,followed by chernozem soil and dark brown soil,accounting for 30.7%,18.2%,and 9.1%of the cultivated land area respectively.2.It reveals the growth and decline trend and evolution characteristics of black soil cultivated land in Songnen Plain.Using GIS overlay analysis technology,after comparative analysis of remote sensing data at two time nodes,the area of black soil cultivated in the Songnen Plain of Heilongjiang Province increased from 79502.73 km2 in 2000to88050.56 km2 in2019.The amount of change is summarized as follows:First,other land The type changed to 21449.17km2 of cultivated land,and the second was the transfer of cultivated land to other land of 12901.87km2.In general,the relative variable of cultivated land area in this area has limited growth,but the absolute variable of cultivated land transferred in and out has a large change,especially some may cause Indicators of adverse effects(such as woodland and grassland reclamation,wetland development)and local areas(such as Heihe City)performed well.3.Clarify the current situation,growth and decline trends and evolution characteristics of black soil arable land in Songnen Plain.Using CSLE and the wind erosion model of cultivated land,combined with the digital results of related elements,the solution analysis of the soil erosion intensity of cultivated land was carried out.The results showed that the total area of black soil cultivated land hydraulic wind erosion in the Songnen Plain in 2019 was 36676.55km2,accounting for the total area of cultivated land.41.7%.Among them:the water erosion area is 32651.29km2,mainly distributed in the northern and eastern Songnen Plain and the flooded agricultural areas in the east;the wind erosion area is 4025.26km2,mainly distributed in the agricultural and pastoral wind and sand areas in the western Songnen Plain.During the evaluation period from 2000 to 2019,the soil erosion area of cultivated land in the black soil area decreased from 39758.59 km2 in 2000 to 36676.55 km2 in 2019.It is divided according to the growth and decline of various intensity levels,of which the slight erosion change is +7638.40 km2.The change of moderate erosion is-9241.10km2,the change of strong erosion is-1701.48km2,the change of extremely strong erosion is +32.39km2,and the change of severe erosion is-3675.14km2.The overall situation of the evolution of soil erosion has slowed down.4.Carry out remote sensing evaluation of soil erosion control effect.Based on the identification of black soil cultivated land and the study of the trend of growth and decline,the soil erosion of cultivated land is still a limiting factor for the sustainable development of agriculture in this area.It is urgent to carry out the evaluation of the effectiveness of soil and water conservation,guide the scientific management of soil and water loss,and adopt remote sensing data and soil and water conservation monitoring results to pass typical Analysis and macro-survey carried out the evaluation of soil and water conservation effects,and the results showed that since 2010,the accumulated area of 453.45 km2 under the key soil and water conservation projects has been implemented on black soil cultivated land.The agricultural development project implements water and soil conservation tillage measures of 2598.36 km2.The soil erosion area of arable land decreased from 39758.59 km2 in 2000 to 36676.55 km2 in 2019.Among them,the area of moderate or above soil erosion decreased by 14485.33 km2,a decrease of 64.5%.The total annual runoff that can be intercepted by various projects in the treatment area is 31795.26×104m3/a,the total soil preservation amounted to 651.37×104t/a,which is equivalent to the annual loss of black soil cultivated land of 1,736.98hm2.5.Propose regional soil erosion control strategiesBased on the project research results,in view of the strong changes in the transfer of cultivated land during the evaluation period,the analysis of the sensitivity and vulnerability of soil erosion in typical black soil areas,and the characteristic law of reduced intensity and slight increase in soil erosion during years of soil erosion control,it is passed The analysis of the social management mechanism and the policy environment respectively proposes strategies for optimizing the development of land and space to prevent the expansion of the transfer of cultivated land;concentrate advantageous resources to carry out large-scale control of cultivated land erosion in typical black soil areas;raise standards and increase investment,To accelerate the pace of soil erosion control.In order to do a good job in regional water and soil conservation and protect black soil cultivated land,scientific suggestions have been made.At present,41.7%of the cultivated land in the black soil of Heilongjiang Province is under the stress of soil erosion.At present and for a period of time in the future,the black soil cultivated land will face the severe challenges of increasing soil erosion and thinning of the cultivated layer for a long time.We should increase support for the black soil conservation technology support projects,Speed up the ecological environment improvement and soil erosion control in the black soil area,protect the black soil,and build the North Dacang.