Change of species diversity on typical Stipa bungeana community restoration and succession in the Yunwu Mountain

The dynamic changes in community height,coverage,abundance,above ground biomass and plant diversity in Stipa bungeana typical steppe was investigated by a quadrat method.There were six treatments: Unexclosure(W),5-year old exclosure(5 a),10-year old exclosure(10 a),15-year old exclosure(15 a),20-year old exclosure(20 a),and 25-year old exclosure(25 a) plots.The 10 a plot had the highest community average height,abundance,and above ground biomass,but the community average increased with enclosure time and the 25 a plot had the highest community average coverage.Enclosure for 10 a gave the highest species diversity index in the third plots,while 15 a had the highest richness index and lowest evenness index.The highest evenness index was in the non-enclosure plot.Exclosure appears to maintain or conserve,rather than increase plant diversity in contrast to non-enclosure.In conclusion,exclosure can significantly improve grassland productivity for a time and this study has shown that the best exclosure for S.bungeana communities is 10-15 a,there would be no benefit for grassland productivity if the exclosure lasted too long.