Species diversity with natural restoration in slash after control of pine wilt disease

After a 17-year natural restoration period on Zhoushan Island，a resurvey of seven typical pine plots of masson pine（Pinus massoniana），Japanese black pine（Pinus thunbergii），and combinations of broadleaf and conifer forests，set up before occurrence of the pine wilt disease，was undertaken. Results showed that sample sites evolved to conifer-broadleaf mixed forest or broadleaf forest types with diversity of the tree layer increasing. Ranking of tree layer diversity was as follows：succession of pure masson pine forest to deciduous broadleaf forest and mixed，evergreen and deciduous broadleaf forest＞succession of Japanese black pine forest to deciduous broadleaf forest＞succession of pure masson pine forest to conifer and broadleaf mixed forest＞succession of a mixed forest of Japanese black pine and broadleaf trees to deciduous broadleaf forest＞succession of a mixed forest of masson pine and broadleaf trees to evergreen and deciduous broadleaf mixed forest. Also，in the mixed forest of masson pine and broadleaf trees，diversity of regeneration layer and shrub layer decreased，in the Japanese black pine forest diversity of the regeneration layer increased，other forest stands changed little，and diversity of the herb layer decreased. After natural restoration，diversity of vegetation types exhibited little similarity. Based on the dynamic variation rule of species diversity during natural restoration as well as conditions on Zhoushan Island，species diversity should be enriched and the landscape improved with island native zonal vegetation. ［Ch，2 tab. 21 ref.］