Rapid revegetation by sowing seed mixtures of shrub and herbaceous species

摘要

Fast revegetation by means of sowing seed mixtures of shrub and herbaceousspecies is a measure to prevent bare soils from wind and water erosion. Afield experiment was used to test the effect of species selection and theratio of shrub to herbaceous species on vegetation formation and shrubgrowth. Results showed that herbaceous species hastened cover formation andmaintained a high coverage for a longer period. However, the growth of shrubswas hindered. In the North China Plain or where the soil and climate aresimilar, the ratio of shrub to herbaceous seeds is proposed to be6 : 4–7 : 3 (weight ratio). Among the herbaceous species tested,Festuca arundinacea Schreb. grows relatively slow, so it should be mixed with other fast-growingspecies in the practice of rapid revegetation, and a seeding density lowerthan 6 g m?2 is proposed when applied; Orychophragmus violaceus O. E. Schulz. wiltswhen the seeds are ripe, leading to a significant decrease of coverage, soother species with different phenology should be involved when it isapplied; Viola philippica Car. is a good ground cover plant which grows fast and maintainsa stable coverage from July to October, and a seeding density of 1.5 g m?2 is proposed for rapid revegetation. Herbaceousspecies have different traits. Three different types of herbs were found inour experiment: slow-growing stable species (F. arundinacea), fast-growing unstablespecies (O. violaceus) and fast-growing stable species (V. philippica). Shrubs, slow-growing stablespecies and fast-growing unstable species should not be used alone becausethey cannot cover the ground fast or they cannot maintain a long period ofgood coverage. A small seeding rate of fast-growing stable species should beused to ensure a fair coverage against erosion. Because naturalenvironmental conditions are heterogeneous and stochastic, more speciesshould be added to enhance the stability of plant community.