Diversity,spatial pattern and dynamics of vegetation under urbanization in Shanghai(V):Natural succession pattern of understory vegetation in Metasequoia glyptostrobodies plantations without management in urban areas

The dynamics of species composition and diversity,population structure and height growth rate of understory vegetation in the Metasequoia glyptostrobodies plantations abandoned for 5,8 and 12 years in the campus of East China Normal University has been studied in this paper.The results indicated as follows.(1) The species diversity decreased after abandoned.(2) Understory vegetation mainly distributed on the layer of 0-1.5 m and 1.5-3.0,in which the main species is Trachycarpus fortunei due to rich seeds sources.(3) The population structure pattern shifted from sporadic type to unimodal type,and its restoration has been changing into deflected succession.And(4) Trachycarpus fortunei and Ligustrum quihoui with the character of shade-tolerant have fast height-growth rate.It is suggested that the habitat,the seed resources and the seed dispersal pattern were the key limitation of understory vegetation restoration.