Study On The Technology Of Planting Woody Plant On Highway Side Slopes In Southwest Mountainous Area Of Hunan Province

Planting of woody plant communities on slope is one side of applying bioengineering techniques for slope protection. It is that using versatile and multi-level plant materials including arbor and shrub, rather than single herbaceous plant. Its final aim is planting vegetation community as environment, restoring the original ecological environment to a maximum extent, and protecting highway slope effectively. The technology of bioengineering techniques for slope protection we have got at present mainly planting pure herbaceous or shrub-grass community with a few of shrub. It has single plant species and lean vegetation level .Not only the effect of protecting water and soil and conserving water, but also landscape effect is bad. It is difficult to coordinate with the landscape around. The paper chooses the expressway from Shaoyang to Huaihua as research object, and studied the selection of adaptable plants, comparison of construction technology about planting of woody plant communities, and technology of planting woody plant on rocky slope, in order to put forward a scheme pertinently. Conclusions are as follows:(1) The study summarized 40 plant species successfully used in ecological slope protection and common seed plants along expressway from Shaoyang to Huaihua in Hunan, and provided well basic data for construction of expressway at mountain area of Hunan. Based on adaptability and configuration of mixed sowing tests on plants, it selected 8 herbaceous plants (including Eragrostis curvula, Eremochloa ophiuroides, Medicago sativa, Paspalum notatum, Cynodon dactylon, Lolium perenne, Trifolium repens, Zoysia japonica) and 10 woody plants (including Robinia pseucdoacacia, Leucaena glauca, Indigofera amblyatha, Pyracantha fortuneana, Lespedeza bicolor, Amorpha fruticosa, Rose multiflora, Cajanus cajan, Lyciμm chinense, Cassia corymbosa).(2) Through 7 tests of construction technology, it concluded that using thick layer base material spraying bio-slope-engineering on steep weathering rock slope, importing Bop net spraying bio-slope-engineering on strong decomposed rock slope, using geotechnical pattern room of soil-fixation bio-slope-engineering on relatively gentle weathering rock slope, and using hole planting woody plant and mixed sowing herbaceous plant, and so on.(3) Planting woody plant communities on tock slope can be true through using thick layer base material and Bop net spraying bio-slope-engineering.the study concluded the ratio of thick layer base material for planting woody plant communities on tock slope of the expressway from Shaoyang to Huaihua by observing various indexes in the test and taking calculation analysis. That is: rock greening material 30%+ local planting soil 65%+ fibers 5%. (4) Based on types of rock slope, spraying thickness of base material are divided into 4cm of strong decomposed rock, 7cm of weathered rock, 10cm of hard weathered rock.(5) Plant germination, coverage in a certain period, and structure of community after 3 years were tested and analyzing at the test on seeds ratio of base material. It concluded best seeds ratio. The conclusion is as follow: the seed ratio of good protection effect at prophase and well goal community at anaphase is Cynodon dactylon 0.61g +Trifolium repens 1.05g+ Lolium perenne 0.37g+ Indigofera amblyatha 7.88g+ Amorpha fruticosa 12.86g+ Robinia pseucdoacacia 26.04g. The seed ratio of relatively poor protection effect at prophase but well goal community at anaphase is Cynodon dactylon 0.20g +Trifolium repens 0.53g+ Lolium perenne 0.17g+ Indigofera amblyatha 8.75g+ Amorpha fruticosa 11.43g+ Robinia pseucdoacacia 26.04g. However, the advantage of this ratio is with low seed dosage and low cost.