Understory herbaceous composition and diversity patterns of forest community in Fanjingshan mountain
[Objective]As a component of forest ecosystem,understory herbaceous play an important role in maintaining biodiversity and coordinating structure and function of ecosystem.The aim of this study is to clarify the composition of understory herbaceous,diversity characteristics and influencing factors in different forest communities in Fanjingshan mountain,and provide scientific basis for biodiversity conservation,scientific management and health assessment of forest ecosystem.[Method]The 15 30 m×30 m forest community permanent plots with elevation ranged from 634 to 2 382 m were set up in Fanjingshan natural reserve located in Guizhou,China,and the understory herbaceous composition was investigated using typical quadrat method,the correlation between herbaceous diversity and elevation as well as stand density were analyzed by means of correlation analysis.Meanwhile,the changes of α,β diversity of understory herbaceous along elevation and stand density gradient were revealed,and the environmental factors impacting herbaceous diversity were discussed.[Result]1)There were 146 species of herbaceous vascular plants belonging to 97 genera and 50 families in 15 forest community permanent plots,among them,44 species,belonging to 20 genera and 10 families were pteridophyte,and 102 species,belonging to 77 genera,40 families were angiosperm.Dryopteridaceae,Athyriaceae,Asteraceae,Orchidaceae,Asparagaceae and Polypodiaceae were the dominant families,accounting for 38.36%of total species.Specie number and important value of herbaceous were variable in different communities,herbaceous specie number ranged from 2 to 40,plot 8 was the richest,while plot 14 was the least.The important value of herbaceous ranged from 0.31 to 58.21,and Pteridophyte were relatively high,while casual species and companion species were relatively low.2)The Margalef index(0.43-5.50),Simpson index(0.18-0.88),Shannon-Wiener index(0.33-2.59)and Pielou index(0.46-0.83)all did not demonstrate obvious change with the increase of elevation and stand density.The regression analysis showed that:except Pielou index,Margalef index,Simpson index and Shannon-Wiener index slight negatively correlated with elevation,whereas all diversity indices showed a low positive correlation with stand density.3)Jaccard index overall presented a downward trend with increasing elevation which indicated that the species turnover rate of different communities was gradually increased,however,Cody index showed an upward tendency with the increase of elevation.Jaccard index and Cody index fluctuated with the increase of stand density and did not appear significant change.[Conclusion]Both elevation and stand density had effects on understory herbaceous composition and diversity of forest communities in Fanjingshan mountain,but both of them did not strongly correlate with diversity indices,and did not play a decisive role in formation and maintenance of herbaceous diversity.
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