几种工程措施对黄土区陡峭边坡植被盖度的影响及其机理

陡削以兰州新区的一段陡峭边坡作为试验地点,通过分析在植被重建初期经人工整地后形成的4种微地形(大圆形坑、小圆形坑、条形坑和原状坡面)的植被盖度特征及环境因子(土壤硬度和水分、地表和空气温度、坡位、无纺布)对植被盖度的影响,探寻能有效提高植被盖度的几种工程改造措施。研究表明:①铺设了无纺布坡面的植被盖度显著大于对照坡面;陡峭边坡不同坡位的植被盖度:下坡位>中坡位>上坡位(P<0.05),这与自然坡面植被盖度分布规律一致。②3种微地形的植被盖度均显著大于陡峭坡面,其中条形坑的土壤水分和植被盖度最大,最大盖度维持的时间最长。③微地形和坡面的植被盖度均与土壤水分呈显著正相关,与空气温度、地表温度均呈显著负相关;微地形的土壤硬度(3kg·cm^-2)适宜植物生长,大于该值会对植被生长产生抑制作用;铺设无纺布有利于促进上坡位的植被生长,使坡面植被分布更均匀。研究结果表明,在陡峭边坡坡度、坡位和温度等无法改变的情况下,选择对压实的坡面进行整地翻耕处理,增加长条坑的数量并铺设无纺布等有效的工程改造措施,能显著增加植被盖度,促进植被恢复。

Effect of Several Engineering Measures on Vegetation Coverage on Steep Slope in the Loess Region

In this study,a section of steep slope in Lanzhou New Area was taken as the experimental site to analyze the characteristics of vegetation coverage over 4 kinds of micro-topography (long pit,small circular pit,large circular pit and original slope) formed after artificial land preparation at the early stage of vegetation reconstruction.Moreover,the environmental factors affecting vegetation coverage,including the soil hardness,soil moisture content,surface temperature,air temperature,slope position and slope covered with nonwovens,were also analyzed so as to look for several engineering measures to effectively improve the vegetation coverage. The results showed that:①The vegetation coverage on the slope covered with nonwovens was significantly higher than that on the control slope,and the vegetation coverage at the different positions of steep slope was in an order of lower slope > middle slope >upper slope,which was consistent with the distribution of vegetation coverage on natural slope.② The vegetation coverage over 3 kinds of micro-topography was significantly higher than that on the steep slopes,in which the vegetation coverage,soil moisture content and duration of maximum vegetation coverage over the long pit were the highest and longest.③ The vegetation coverage over the micro-topography and slope was positively correlated with soil moisture content,but negatively correlated with air temperature and surface temperature. The soil hardness of microtopography at 3 kg·cm^-2 was suitable for plant growth,and it would restrict the plant growth if it was higher than this value. It was conducive to the growth of vegetation on the upper slope if it was covered with nonwovens. The results above revealed that,under the conditions that the slope gradient,slope position and temperature of steep slope could not be changed,the vegetation coverage could be effectively promoted by some engineering measures,such as land preparation and tillage on compacted slope,increase of the number of long pits and covering of nonwovens.