西南地区几种典型边坡植被的护坡效益分析

植被对边坡防护有着非常重要的作用，但其防护效果易受配置模式及建植年限的影响。以西南地区5种典型边坡植被配置模式为对象，比较了不同配置模式的护坡性能及建植年限等因素所致的年际间差异。坡上设景观过渡带（株行距分别为0.5 m×0.5 m，0.05 m×0.1 m的小乔木、地被植物），坡下为不同配置的坡面防护带（喷播密度为10 g/m²的灌木、草本植物）:M₁为慈竹—野牛草，M₂为小冠花—紫羊茅，M₃为苜蓿—狗牙根，M₄为小冠花—黑麦草，M₅为黄荆—狗尾草。测定了成渝高速永川段2012—2014年各植被配置模式在自然降雨条件下的产流、产沙特征。结果表明:（1）建坪初期，狗尾草所在群落（M₅）生长快、成坪早，在2012年汛期即呈现较强的护坡性能:蓄水、保土能力分别达到59.14%，96.22%，产流量、产沙量（61.2 mm，52.0 g/m²）也明显低于其他小区（p < 0.05）；狗牙根、黑麦草等多年生草本所在群落成坪迟、生长慢，护坡性能普遍较差。（2）2013年汛期，M₁—M₄的护坡性能较2012年明显提高，以M₃，M₄最为显著。（3）2014年汛期，具有发达根系的狗牙根所在群落护坡性能最强:蓄水、保土能力分别达到80.03%，98.49%；M₅的护坡性能最差，其产流量、产沙量（62.1 mm，150.33 g/m²）也明显高于其他观测区。相同降雨条件下，边坡植被的护坡性能与群落结构有关，即建坪初期与地上生物量大小正相关，之后与根系重量正相关。

Analysis of Ecological Benefits of Side Slope Protection by Typical Vegetation Along the Highway in Southwest Areas

Using localization shrubs to reconstruct plant communities plays a very important role in superhighway side slope ecological protection, but its protection effect is easily affected by the configuration mode and reconstructing years. In this case, five typical vegetation modes composed by landscape transitional zone (ornamental arbors with 0.5 m×0.5 m of spacing + ground-cover plants with 0.05 m×0.1 m of spacing inthe rows) and slope protection zone (shrubs + herbages with 10 g/m² of planting density), including Neosino calamus affinis—Buchloe dactyloides (M₁), Coronilla varia—Festuca rubra (M₂), Medicago falcate—Cynodon dactylon (M₃), Coronilla varia—Lolium perenne (M₄) and Vitex negundo—Setaria viridis (M₅), reconstructed. Chengyu expressway in Yongchuan were taken as the example and foundation, their characteristics of runoff and erosion sediment in rainy seasons in the years from 2012 to 2014 were investigated, and the annual fluctuation of their ecological slope protection capacity was analyzed. Results showed that:(1) the annual herbaceous plants in the grass-shrub community, i. e., Vitex negundo+Setaria viridis grew rapidly, which turf-establishment stage (65 d) was transitory, its capacity of soil and water conservation (80.03% and 98.49%, respectively) were higher than other modes in the first growing season after turf-establishment (2012), and among five vegetation modes, its runoff and sediment yield (61.2 mm and 52.0 g/m², respectively) were the lowest(p < 0.05). However, the perennial herbs (e.g., Cynodon dactylon, Lolium perenne and so on) in the grass-shrub communities grew tardily with more laggardly turf-establishment stages, and their outstanding capacities of soil and water conservation only showed in the second or third growing season after turf-establishment; (2) in the rainy seasons in 2013, ecological protection benefits of the grass-shrub communities (M₁—M₄) including perennial herbs improved apparently, which were especially outstanding in Coronilla varia+Lolium perenne (M₄) and Medicago falcate+Cynodon dactylon (M₃); (3) in the third growing season (2014), performance of artificial vegetations Medicago falcate+Cynodon dactylon (M₃) was the most excellent in slope protection by means of developed root system of Bermuda grass, its capacity of soil and water conservation were 80.03% and 98.49%, respectively, its runoff and sediment yield were no more than 32.40 mm and 17.67 g/m², respectively, and in contrast, that of M₄ was the worst in the slope plot experiments where artificial vegetations were planted. Therefore, it can be seen that ecological protection benefit of artificial vegetation was closely related to their community characteristics, there was a positive correlation between the aboveground biomass of vegetation and their capacity of soil and water conservation in initial succession with determination coefficient (R²) more than 0.987, and did so between root biomass and these capacity in latter succession(R²≥0.998) when there were the same side slope conditions, seed quantity and planting measures.