Forest Types Structure And Regeneration Of Schima In Yunnan

We investigated 70 forest communities containing species of Schima as one of the dominants in Yunnan Province.We identified forest types,analyzed forest structures,species diversity,population characteristics and their regeneration,as well as the plant community successional phases for species of Schima.According to the similarity dendrogram based on vegetation data of 20 plots of primary forests,there are 5 forest types:Type 1,Schima noronhae-Castanopsis ceratacantha forest(an evergreen broad-leaved forest);Type 2,Castanopsis echidnocarpa-Schima khasiana forest(an evergreen broad-leaved forest);Type 3,Tetracentron sinense-Schima villosa forest(a deciduous and evergreen broad-leaved mixed forest);Type 4,Castanopsis platyacantha-Schima sinensis forest(an evergreen broad-leaved forest);Type 5,Castanopsis orthacantha-Formanodendron doichangensis-Schima wallichii forest(an evergreen broad-leaved forest).The frequency of individuals in DBH-classes and regeneration of all the species of Schima in the various primary forests are in a sporadic type.According to the similarity dendrogram based on vegetation data of 50 plots of secondary forests,there are 6 forest types:Type 1,Schima argentea forest(an evergreen broad-leaved forest);Type 2,Schima khasiana-Dipentodon sinicus forest(an evergreen broad-leaved forest);Type 3,Tetracentron sinense-Schima villosa forest(a deciduous and evergreen broad-leaved forest);Type 4,Castanopsis platyacantha-Schima sinensis forest(an evergreen broad-leaved forest);Type 5,Schima villosa-Rhoiptelea chiliantha-Castanopsis remotidenticulata forest(an evergreen and broad-leaved mixed forest);Type 6,Schima sinensis-Castanopsis platyacantha forest(an evergreen broad-leaved forest).The frequency of individuals in DBH-classes and regeneration of all the species of Schima in the various secondary forests are in inverse-J or sporadic types.The regeneration of species of Schima of the first three secondary forest types is stronger than that of the latter three secondary forest types.The Shannon-Wiener diversity index in the primary forest is significantly higher than that of the secondary forest,though the average species richness and the Simpson diversity index between the primary and the secondary forests are not significantly different.Between the primary and the secondary forests,the Sorensen's similarity index(beta diversity)is 0.53.Among the studied 7 species of Schima including S.argentea,S.khasiana,S.sericans,S.sinensis,S.villosa and S.wallichii are heliophilous at the seedling/saplingstage,but in their later life stages these species have plasticity that they can tolerate somewhat shade and co-exist with other species for a long time.They are often dominated secondary forests at the early or early-middle successional phases of the subtropical evergreen broad-leaved forest;however,they also can be a second or third dominant in the primary forest at the late-middle or late successional phases.Recruitments of the 6 species of Schima in the secondary forests with unclosed canopy are much better than those in primary forests with closed canopy.S.noronhae is bimodal that it has an intermediate trait between shade-tolerant and light-loving.S.noronhae is found as the first dominant species in the primary forest;however,it is rare in the secondary forest at the early and early-middle successional stages.