The elevational patterns of β diversity of Picea crassifolia communities on northern slope of Qilianshan Mountain.

Qilianshan National Nature Reserve is a key area for biodiversity in China.Based on the data collected from the 16 sampling plots which 400 m2 per plot selected from representative Picea crassifolia community in six natural forest protection stations,the vertical distribution pattern β diversity were studied.The results showed that: the number of mutual species,SΦrenson index,Cody index and Jaccard index had a general trend of decrease following by increase between adjacent plots with the elevation increased.Along with the elevation gradient increased,in moss and P.crassifolia forest,the species showed a decreasing trend,mutual species,SΦrenson index and Jaccard index decreased after the first increasing trend,and Cody showed a first up after lower trend;in grasses and P.crassifolia forest,the mutual species,SΦrenson index and Jaccard index has been declining and Cody index increased after the first decreasing trend;in mixed P.crassifolia forest,species and mutual species showed a deceasing trend,SΦrenson index and Jaccard index showed a gradually decreasing trend and Cody index showed gradually increasing trend.The correlation between P.crassifolia community and elevation was not significant,the correlation between all diversity index displayed different characteristics.