The Influence Factors Of Vegetation Restoration In Cutting Slope Along Tong Huang Expessway

Exessway construction is important to promote the economic and social development, but it destroyed the original slope vegetation in mountain regions,caused rock exposed and serious ecological problems.So mountain highway slope vegetation restoration has became an important part of ecological construction.The gradient of Tong-Huang exessway's cutting slope is steep, it's hard to grow with vegetation in the slope, so it's necessary to study on Tong-huang expressway cutting slope vegetation restoration.This paper analysises the cutting slope vegetation characteristics and soil physical and chemical properties, the result shows that:(1) Level trench samples are at disadvantages on vegetation coverage,biomass, species richness,diversity and so on than the other slope samples,so level trench failed and it's unsuited on slope protection of Tonghuang expressway.The effect of combination of shrub-grass is better than unitary planting for slope protection,the vegetation growth status of natural samples are better than slope samples.(2) Through the analysising the soil physical and che mical properties,0-10cm soil layers contain more nutrients than 10-20cm soil layers.Spraying seeding samples and hole seeding samples are at a lower level at organic matter and hydrolyzable nitrogen; Level trench and hole seeding samples has less Valid Phosphorus and Available Potassium than others,hole seeding samples are at the lower level on water contens;spraying seeding samples's Bulk Density are more lighter.The soil of Tongchuan-Huangling expressway slope samples are sand soil,and their PH are more than 7.8,so they are alkaline soil,and little difference in water soluble salt content.(3) After with factor analysis, we got that vegetation coverage,water content, available potassium,plant density, underground biomass,PH,aboverground biomass and bulk density of soil are more important on vegetation restoration.Analysising the relationship between vegetation characteristics and soil physical and chemical properties with the Grey relational degree method,it can be found that the correlation coefficient of available potassium, organic matter and water content are bigger than others with vegetation coverage,they are 0.764,0.724 and 0.719;the correlation coefficient of water content,PH and soil tempreture are bigger than others with aboveground biomass,they are 0.782,0.755 and 0.730,the correlation coefficient of water content,available phosphorus and hydrolyzable nitrogen are bigger than others with aboveground biomass,they are0.710,0.706and0.705.So base on the analysis result,soil water and soil nutrient shoule be underappreciated. (4) According to the analytical result,we should keep awareness of water saving awareness,handle the slope,increase water infiltration;and protect and use the topsoil,and keep the nutrients balance in slope fertilization;filter the vegetation of slope reasonably,use more gramineous and leguminous plants,and the way of combination of shrub-grass,optimize the allocation of community.(5) Throughing the two investigations,vegetation of samples are withered and coverage is very low in June, but vegetation of samples increased a lot in July.Because some Liana growed well, they promoted the landscape effects of samples.Vegetations are hard to survival on cutting slope,but they are growed well on platforms of the slope. So plantting Liana on platforms of the slope could improve the landscape effects of the expressway.