Niche of epiphytic bryophytes on trees in Shanghai City

Niche theory is valuable in plant ecology,but not introduced in the research of epiphytic bryophytes on trees.In this paper,18 sampling sites at the main parks,streets,and campuses in Shanghai City were selected,and the epiphytic bryophytes on ten trees in sixteen 20 cm×20 cm quadrats of each site were sampled at 4 heights above the base of tree trunk and 4 exposures.43 species of epiphytic bryophytes including 39 mosses and 4 liverworts were recorded.The niche breadth of the 43 species calculated by Levin's equation based on their coverage showed that the relationship between species number(N) and niche breadth(B) followed N=0.3423 e~(-0.0369B),r=0.9347.Most epiphytic bryophytes had rather narrow niche breadth,and 67.44% of them had a niche breadth less than 0.1,suggesting that in the protection of bryophytes,more attention should be paid on the protection of epiphytic bryophytes on trees and of their special habitats.The niche overlaps of the 43 epiphytic bryophytes species were calculated by Wang's equation,and the ordination plot of Principal Component Analysis(PCA) and the Minimal Spanning Tree(MST) were drawn.The results showed that these 43 epiphytic bryophytes species could be classified into three ecological groups,which had significant correlations with habitats.