先锋植物丰富度对公路边坡植物群落生长发育及护坡效益的影响

Effects of Pioneer Plants Richness on the Vegetation Growth and Community Succession and the Soil and Water Conservation for Highway Side Slope

乡土植物灌木化建植是高速公路边坡防护的重要途径。以成渝高速(永川段)为例,以西南地区2种典型的边坡绿化初始配置模式慈竹+野牛草、黄刺玫+黑麦草为基础,分别与紫穗槐、黄荆、狗牙根、芒等路域优势种以不同方式组合,研究先锋植物丰富度对公路边坡植物群落生长发育、早期演替及护坡性能的影响。结果表明:1)先锋植物丰富度可直接影响边坡植被的成坪时间、生物量积累,相同建植条件(边坡条件、播种密度等)下,初始绿化植物的种类越多,成坪时间越短,被积累的生物量也越多;2)先锋种数量与群落的生物多样性水平有关(R2>0.995),相同演替阶段内,先锋种越多,群落的多样性水平(物种丰度、Shannon-Wiener指数、Pielou指数等)越高;3)群落的生物多样性水平与植被的护坡性能呈线性关系(R2>0.995),多样性水平越高,植被的蓄水、保土能力越强,边坡内径流系数、土壤侵蚀模数越小。在边坡条件、播种密度等建植条件与建植措施一致的情况下,提高初始绿化植物的丰富度可有效改善边坡植被的护坡性能。

Reconstruction of plant communities with native shrubs is one of principle important ecological modes in superhighway side slope protection. In a case of Yongchuan region along Chengyu expressway, two typical vegetation configuration modes, i.e. Bambusa emeiensis ＋ Buchloe dactyloides and Rosa xanthina ＋ Lolium perenne, were used as the foundation for slope protection in southwest areas. Two native shrubs, Amorpha fruticosa and Vitex negundo, and two herbs, Cynodon dactylon and Miscanthus sinensis, were chose to plant with the different modes and growth proportion. The characteristics of slope runoff and sediment erosion in rainy seasons were measured in a plot experiment during 2010 to 2012 to study effects of pioneer species richness on growth and development of plant communities on highway slope, the early successional and the slope protection performance. Results showed： 1 ） Pioneer plants richness affected accumulation of vegetation biomass and period of turf-establishment, and the more abundant pioneer plant species, the shorter turf- establishment period and more accumulation; 2） Richness of pioneer plants were closely related to plant species diversity in the communities with determination coefficient in excess of 0. 995 （ P 〈 0.05）. At the same succession stage, the more abundant pioneer species, the higher plant species diversity including the number of species, Shannon-Wiener index and Pielou index in the communities; 3） There was a positive correlation between the soil and water conservation capacity of vegetation and plant species diversity in the communities with determination coefficient in excess of 0. 995 （P 〈 0.05） , and the higher plant species diversity, the stronger capacity the soil and water conservation with the smaller runoff coefficient and lower soil erosion modulus. Our results suggested that an increase in pioneer plant species richness should be a feasible way to improve ecological slope protection, especially when there were same side slope conditions, seed quantity and planting measures.