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Subtropical evergreen broad-leaved forests (EBLF) of Yunnan,China,including mid-montane moist,monsoon,and semi-humid categories,were studied in terms of structure,diversity and dynamics.The vertical structure of primary subtropical EBLF in Yunnan was multilayered,including canopy,subcanopy,shrub layer and understory.Most of the dominant canopy tree species of the forests had the multimodal type of frequency of size distribution.The monsoon EBLF yielded the highest indices of the Shannon-Wiener H,Equitability J,Simpson D and Fishers alpha,followed by the mid-montane moist EBLF,then by the semi-humid EBLF.As a result of long-term human activity in the area,the plant communities ranged from pioneer deciduous broad-leaved and/or pioneer coniferous stands to latesuccessional evergreen broad-leaved stands.In central Yunnan,the secondary successional pathways were from pioneer deciduous stands of Alnus and Platycarya,accompanied by stands of pioneer coniferous Pinus and Keteleeria,through broadleaved and coniferous mixed stands,to late-successional evergreen broad-leaved forests of Cyclobalanopsis and Castanopsis.In the subtropical mountain area of Yunnan,the EBLF is commonly replaced by plantations of exotic fast-growing Eucalyptus to produce industrial wood,oil,pulp and fuel.The result has been reduced plant diversity,with low canopy interception and great loss of soil nutrients by erosion,as compared to the EBLF.Eighty-one plant species in the area have been ranked as rare,endangered,or threatened.Their condition is seen as largely attributable to habitat degradation.A clear understanding of ecological features and successional pathways of the EBLFs provides a basis for evaluating the sustainability of the forests in relation to human activity,and can lead to more effective conservation and management of these fragile forests and the mountain ecosystems.