Study On Soil Erodibility Of Core Area Of ​​Arid Valley In Upper Reaches Of Minjiang River

Dry river valley is the upper Yangtze river mountain ecological environment is the most weak, there is a problem, most is in the key and the most difficult mountain governance type, a special area with a small environmental capacity and ecological low threshold characteristics. Due to a serious disturbance of man-made factors, lead to serious soil erosion, landslides, the natural disaster such as mud-rock flow, combined with obvious foehn effect and the background of global climate change, drought river valley distribution area is increasingly larger and more stability, its drying trend and tendency of the desertification development has become the upper Yangtze river ecological environmental degradation is one of the most typical performance. Based on the dry valley of the upper reaches of minjiang river cores of different slope direction as the research object, through the investigation of vegetation in different slope direction characteristics and soil sampling, using EPIC model to estimate the soil corrosion K value, and analyzes the different slope to the soil corrosion characteristics and vegetation distribution characteristics and the relationship between the soil corrosion K value, the results of the study on regional soil erosion process prediction and effective control of soil and water loss, restore the ecological environment has important significance. The main results were as follows:(1) Soil erodibility six evaluation indicators, sunny and semi-shady slope clay content the most sensitive, followed by water-stable aggregates and structural index showed a weak spatial variation sensitive sex. Shady soil organic matter in the most sensitive, followed by clay content, silt content and bulk density and other indicators; structural index showed a weak sensitivity to spatial variability. Criteria for the classification based on the sensitivity of soil organic matter found, clay content, silt content, bulk density and water stability of aggregates and other indicators for the evaluation of soil erodibility sensitive indicator shows the distribution of organic matter and soil aggregates in the evaluation of erodable characteristics important role.(2) The average soil K value sunny 0.3397, range of 0.3084-0.3624; shady soil K values averaged 0.3180 variation,range of 0.2832-0.3472; semi-shady slope soil K values averaged 0.2941, range of 0.2551-0.3373, the maximum is 1.42 times the minimum, showing a larger amplitude measurements. Sunny K values mean 0.3397,0.3429 median, median and mean close, indicating that in the study of soil erodibility K value is more evenly distributed, not subject to the impact of specific value, shady and semi-shady slope on soil erosion the value of K is more evenly distributed. Erodibility K value and show that the study area has a low degree of spatial variability, resulting in soil erodibility becomes larger variability reason so many factors in the study area soil texture, topography, vegetation and other differences.(3) Mostly shrub vegetation dominated Asteraceae, especially Artemisiagmelinii and Ajania potaninii most universal. Due to the strong sunny light, resulting in soil exposed to the sun, the shortage of water, sparse vegetation, cover a minimum of 42.88%; less shady sun, adequate moisture, vegetation growth is more intensive coverage of 64.54%, which irons Artemisia coverage up to 50%; semi-shady slope, not part-time exposure to the sun, moisture and sunlight is more uniform, dense vegetation, cover up to 68%, shrub vegetation under a lot of short-day plant Andropogon, coverage reached 30%.(4) Soil corrosion K value with clay and silt content was significantly positively related, and sand content has significant negative correlation; With the increase of soil organic matter content of soil corrosion K value decreased gradually. Different slope, the lower the temperature, the more precipitation, making organic carbon mineralization rate decreased with increasing organic carbon content, organic matter accumulation increased, the lower the corresponding soil erodibility K value.(5) Characteristics of the study area based on the distribution of vegetation and soil erodibility K value Relations, soil erodibility factor K value greater sunny, erosion-prone; soil erodibility factor K values than the sunny little shady, greater ability to resist erosion, soil erodibility factor K value of the minimum half-shady slope, erosion resistance can be in the strongest. Through the soil erodibility factor K value of spatial consistency of the analysis, growth conditions and the extent of soil erosion resistant vegetation closely related, indicating that vegetation is an important factor affecting soil erosion resistance.