Effects of Bare-Ground Revegetation Techniques Using Imperata cylindrica on Changes in the Plant Cover and Species Richness during Early Succession

Abstract

Riverdikes are habitats that must be revegetated quickly in order to prevent soil erosion. With in- creasing pressure to improve the cost efficiency of management, new revegetation techniques suitable under reduced mowing frequencies are required. Imperata cylindrica (L.) P. Beauv. is an important component of grasslands in several Asian countries. Its vigorous rhizome elongation should be useful for quickly covering bare ground. We tested the effects of sowing (at two densi- ties), transplanting, and sodding of I. cylindrica on plant cover and species richness of established vegetation over 3 years. The sodding and high-density sowing treatments achieved the most rapid increase in cover, followed by low-density sowing, transplanting, and the control. By year 2, how- ever, the cover in the low- and high-density sowing treatments was similar. The sodding treatment had significantly fewer species than the other treatments in year 1. Between years 1 and 2 and years 2 and 3, the total number of species increased in the transplanting treatment, whereas it decreased in the sodding and two sowing treatments. Accordingly, if stabilization and erosion control are the priority, introduction of I. cylindrica using sod and high-density sowing is the most suitable method. If immediate green-up is not imperative, low-density sowing is likely to provide available resources for new seedlings of diverse species to become established, allowing the in- troduction of representative species in semi-natural grasslands. More research will be needed on the effects of introducing diverse species (e.g., sowing seed mixtures) that include I. cylindrica on the resulting floristic composition.