| Soil erosion is one of the most serious disaster in the world, which will destroy land resources, resulting in siltation, droughts, floods, other disasters and reduce soil nutrients and clay materials, making soil compaction or degradation. Soil erosion is also the reflection of ecological and environmental degradation and seriously threaten human survival and d evelopment, being an universal concern issue. Muling is a typical of Agricultural land area with fragile ecological environment. Severe soil erosion not only loss limited black topsoil with years, but also declined soil fertility, reduced production of fruit and other crops year by year, becoming a major factor restricting economic development. No matter terrain but also agricultural ecological environment, Muling is a typical study area. In terms of terrain or land and are. Therefore, Muling was selected as the study area, with the support of RS and GIS software to analyze dynamic characteristics of soil erosion and nutrient loss.The results have practical significance on improving land conditions, soil fertility and reducing soil nutrient loss, aiming t o provide a theoretical basis for the prevention of soil erosion. The following conclusions:(1) Mild and moderate are the mainly erosion sensitivity in the study area, and gradually increased from north to south. Fulu is the main distribution area of micr o-sensitivity and extremely sensitivity areas are sparingly located in Xia Chengzi and Ma Qiaohe. Overall, the sensitivity of soil erosion is not obvious, without strong sensitivity areas, but mild and moderate sensitivity areas are distributed widely in Muling.(2) From 2009 to 2013, gully density have increased from 0.14 km / km2 to 0.17 km / km2 in Muling. The range of grid density increased from 0.002 km / km2- 8.601 km / km2 to 0.060 km / km2-7.294 km / km2, and the average of gully density increased from 0.135 km / km2 to 0.931 km / km2.(3) Compared with 2009, soil erosion intensity have increased in 2013, and the distribution of erosion gully significantly expanded, but the distribution of the erosion intensity have the same trend.(4) During 2009-2013, the erosion gully density in the north-central region is relatively larger than in the south of Muling, the core area was located in the central region of Xia Chengzi. Taking the core area as the center, soil erosion, radiate to surrounding with conc entric circles, and the extent of erosion is relatively reduced.(5) In Muling the amount of erosion gully is from 3748 to 3953 in 2009- 2013. The total length of erosion gully is 840.886 km in 2009, and 974.838 km in 2013. The average length of erosion gully increased from 0.224 km to 0.931 km. Range of erosion gully length is 0.001 km-1.539 km in 2009 and 0.044 km- 1.372 km in 2013.(6) In 2009 and 2013, the maximum value of the total length of erosion gully appeared in Xia Chengzi and Hexi, the value is 459.758 km and 247.947 km separately, the total length of the other towns were lower than 200 km and 100 km. The maximum value of the average length appeared in Gonghe, the value is 0.427 km and 0.372 km respectively, and average length of erosion gully in the other towns fluctuated between 0.20 km and 0.35 km.(7) The mean of erosion gully density in the mild, moderate highly sensitive areas is successively increasing, while in the extremely sensitive area the mean of erosion gully density is almost 0. Mild and moderate are the mainly erosion sensitivity in the study area, and erosion gully is also more in the corresponding areas. Sensitivity of soil erosion influenced the number and distribution of erosion gully formation, but the impacts also depend on other factors.(8) Covariance between erosion gully density and soil erosion sensitivity is 0.0086 and correlation coefficient is 0.0620, indicating the soil erosion sensitivity was positively correlated with erosion gully density. Erosion gully has more density in the more sensitive areas of soil erosion.(9) The soil is acidic in Muling. In addition to soil nutrient phosphorus, the mean of organic carbon, available potassium and total nitrogen of woodland is higher than arable land, the content of organic carbon of woodland is about 1.8 times higher than arable land. In addition to phosphorus, the difference of the organic carbon, available K, total nitrogen of arable land and woodland were significant(p <0.05). In addition to soil nutrient phosphorus, in the spatial distribution of the same sampling point, the content of organic carbon, available potassium and total nitrogen of woodland is higher than arable land.(10) In the different erosion gully density gradient, available phosphorus content of farmland is higher than or almost equal to woodlands; total nitrogen did not change significantly. When erosion gully density is 0.10 km / km2, the phosphorus and potassium content of farmland and woodland showing the maximum values; when the density increased to 0.25 km / km2, the content of phosphorus and potassium decreased; density continues increased, the content of the two elements reduced slowly, even increased slowly. The total organic carbon of arable land has low content. |
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