The conservation management of Imperata cylindrica grassland in Nepal with fire and cutting: an experimental approach.
Abstract
Imperata cylindrica dominated grassland in the Nepal Terai supports a number of threatened species including swamp deer Cervus duvauceli, hispid hare Caprolagus hispidus and Bengal florican Eupodotis bengalensis. It is also the main source of thatch material for local communities. Current widespread cutting and burning of the grasslands is deleterious to cover-dependent vertebrates which would benefit from patches of grassland remaining unmanaged. In Royal Bardia National Park, a randomized block experiment with four treatments (cutting, burning, cutting and burning, and no management) was established to examine the effects of these treatments on plant species abundance, species richness and grassland structure. The grassland was dominated by Imperata cylindrica, with Saccharum spontaneum, Vetiveria zizanioides, Desmostachya bipinnata and Schizachyrium brevifolium the other abundant species. In year 3, 2 years after the first treatment, Imperata cylindrica remained the dominant grass species under all treatments. It increased in abundance in unmanaged plots and declined in abundance in managed plots. Desmostachya bipinnata showed the opposite response. Plant species richness was significantly higher in managed plots, which were structurally more heterogeneous. The effects of cutting alone, burning alone, and cutting and burning combined on the structure and composition of the grassland were similar, despite additive effects on total grass cover, total forb cover and forb species richness in cut and burned plots. This allows the effects of cutting and burning to be reduced to a single treatment (cutting plus burning) in future experiments to investigate the impacts of patch harvesting on community dynamics. Simpler factorial experiments can be designed than if cutting and burning had to be considered as separate treatments. There was no difference in the establishment of tall grass species or woody species between managed and unmanaged plots. It is suggested that patches of grassland could be left unmanaged on a 2-year rotation without significantly altering the composition of the plant community, thereby providing refugia for cover-dependent faunal species.