Analysis on the Characteristics of Communities of Ammopiptanthus nanus and A. mongolicus

There are only two species in the genus of Ammopiptanthus: A.nanus(M.Pop.) Cheng f.and A.mongolicus(Maxim.) Cheng f.Both of them are the endemic evergreen shrubs with broad leaves,grow in Central Asian deserts,and are the relic plants from Tertiary.Because of these special characteristics,the study on these two rare and precious plants is necessary and important.In this study,the wild communities of the genus of Ammopiptanthus in some sampling plots were investigated during the period from July 12 to 29,2003.After comparing the communities of A.nanus and A.mongolicus,it is found that they have many similarities: the dominant families in the community are Compositae,Chenopodiaceae and Leguminosae;the principal geographical elements are the temperate element and Mediterranean element;the communities are mainly composed of the xeric perennial herbs and half-shrubs growing over the steppe deserts;the vegetation structure is simply dominated by shrub layer and herb layer;and the vegetation coverage is low.These similarities reveal that the communities adapt the desert habitat.Moreover,they also have many differences.After comparing the flora components of the communities of A.nanus and A.mongolicus,it is also found that they have many similarities in family level but share little common in species level.Compared with the community of A.mongolicus,the community of A. nanus has less flora components,simpler structure,less community types,and low coverage and abundance.However,the evenness of the community of A.nanus is higher than that of the community of A.mongolicus.The stability of both communities,especially the community of A.nanus,is poor.