Analysis On The Effect Of Sloping Landscape Type Combinations On Soil Erosion In Semi-arid Areas Of Western Liaoning

Slope land is one of the main distribution areas of cultivated land resources in China.Slope is the most basic landscape unit that constitutes mountains,hills and broken plateaus,and is also the basic unit of soil erosion.Soil erosion on sloping land causes the migration of surface materials,which is likely to cause problems such as land degradation and reduced land productivity in the mountainous areas,threatening the living environment of people at the bottom of the slope.The area of sloping farmland in Liaoning Province accounts for about one-third of the total cultivated land in the province,and the arable land erosion mainly occurs on sloping farmland.The long-term agricultural cultivation in western Liaoning has made the sloping land distributed a variety of landscape types,which constitute different combinations of landscape types,which have different mitigating effects on slope soil erosion.Based on this,in order to find out the influence of different landscape types on the soil erosion on the sloping land,this paper uses the typical small watershed in the semi-arid area of western Liaoning,Baishan small watershed as the study area,using Arc GIS analysis,landscape index analysis,experimental analysis to analyze the landscape heterogeneity of the plots of different landscape types.Based on soil water content and soil clay content as indicators of soil erosion,the mitigation effects of different landscape types on slopes in small watersheds in semi-arid areas were analyzed.The main results are as follows:（1）The combination of landscape types in Baishan small watershed is complex and diverse,and the degree of landscape heterogeneity is relatively high.The landscape types widely distributed in the basin are rural roads,field ridges,dry land,highway land,and forested land,accounting for 65.086%,29.536%,1.821%,1.184%,and0.873%.Due to different farming methods and engineering measures,farmland can be divided into three types:sloping farmland,level terraced farmland,and slope terraced farmland.The main landscape types include orchard-slope farmland-orchard-slope farmland（OF_SOF_S）,woodland-level terraced farmland(WF_LT),woodland-sloping terraced farmland(WF_ST),woodland-slope farmland-woodland-slope farmland（WF_SWF_S）.),woodland-grassland-slope farmland（WGF_S）,woodland-orchard-slope farmland-orchard（WOF_SO）.The landscape index（DIVISION）of the basin is 0.992,the landscape shape index（LSI）is 59.473,and the Shannon diversity index（SHDI）is 1.654.The overall landscape type is more diverse,the degree of landscape fragmentation is higher,and the degree of landscape heterogeneity is relative higher.（2）When the combination of sloping landscape types is the same,there is little difference in the effect of soil erosion mitigation.However,when the landscape type is different at the slope position,the effect of soil erosion mitigation is slightly different.Both A1 and A2 are landscape types of orchard-slope farmland-orchard-slope farmland（OF_SOF_S）,which have similar effects on soil erosion.The difference between soil water content and clay content on the two slopes was small,0.034%and 0.23%.However,when the landscape type is different at the slope position,the effect of soil erosion mitigation is slightly different.In comparison,when the orchard is distributed in the upper part of the slope,the soil erosion slowing effect is more obvious than that of the slope farmland.The construction of level terraces in the combination of woodland-level terraced farmland(WF_LT)can reduce the degree of soil surface erosion and weaken the loss of soil fine particulate matter,and the most significant effect on soil erosion on slopes.In the woodland distributed in the top of the slope,the soil water content and soil clay content are lower than the level terraces at the same slope position,and the mitigation effect on soil erosion is not obvious.（3）When the combination of sloping landscape types is different,the effect of soil erosion mitigation is obviously different.When the landscape type combination is different,the change trend and value range of soil water content and clay content are obviously different.The soil water content and clay content of 0-20 cm in the landscape type combination of G1 level terraced farmland(F_ST)ranged from 10.33%to 17.98%and 2.62%to 3.62%,while the landscape type combination of G2 orchard-slope farmland-orchard-slope farmland（OF_SOF_S）ranged from 8.10%to 16.00%and 1.80%to 3.50%.Analysis of the difference between 0-20 cm soil water content and clay content,slope farmland（F_S）,woodland-grassland-sloping farmland（WGF_S）,woodland-orchard-slope terraced farmland(WOF_ST),slope terraced farmland(F_ST),slope farmland-orchard-slope terraced farmland-orchard-slope terraced farmland(F_SOF_STOF_ST)have a significant effect on soil erosion mitigation effects.The slope of a single sloping farmland has a more significant effect on soil erosion than the composite slope with woodland and sloping farmland.The slope of the single slope terraced farmland is less significant than the composite slope of the orchard and slope terraced farmland.In general,the combination of non-cultivated landscape types or complex landscape types has a significant mitigation effect on soil erosion.