Species diversity of Prunus mongolica community in Ningxia Helan Mountain Nature Reserve

According to the field survey of Prunus mongolica community,there are 133 vascular plant species(including subspecies),belonging to 91 genura and 39 families.The result of flora analysis showed that Prunus mongolica community in Ningxia Helan Mountain Nature Reserve has characteristics of temperate,and North Temperate component is dominant,accounting for 35.16 %.Hemicryptophytes accounts for almost 50 % in total species among the life form,it indicates that habitat of Prunus mongolica community is cold and dry.The results of measuring species diversity indices show: 1) The species diversity of herbage layer is higher than shrub layer;2) The species diversity is the highest in 1700~1800m of north part,the species diversity is the highest in 2000~2100m of middle area;3) The species diversity is the lowest in shady slope of north area,in converse,the species diversity of shady slope and half shady slope is higher than tailo and half tailo of middle area;4) The species of the slope of less than 20° is higher than the slope of more than 20°,and the species diversity of the slope of more than 20° decreases while the slope increasing.