Frequency and Age Structure of Dominant Species Populations in Eighteen Forest Communities in Northern Guangdong,China

To clarify the present protected status and the development law for vegetation in northern Guangdong,China,the frequency and age structures of dominant species in 18 forest communities were studied by using the method of vegetation quadrat and numerical analysis.The results showed that among 1265 frequency values,78.38% was in Grade A(present frequency of species among 1%-20%),15.38% in Grade B(21%-40%),2.91% in Grade C(41%-60%),1.87% in Grade D(61%-80%) and 1.46% in Grade E(81%-100%) according to the Raunkiaer’s Frequency System of five grades.The frequency law was A>B>C>D>E.Among the 16 age structures of dominant species populations,in which the frequency was more than 60%(grade D and E),the declining populations were Liquidambar formosana,Cunninghamia lanceolata,Castanopsis carlesii,Pinus massoniana,Alniphyllum fortunei,Cinnamomum porrectum,Castanopsis lamontii and Choerospondias axillaries;the increasing populations were Castanopsis hystrix,C.fissa,and C.fabric;and the stable populations included Castanopsis eyrei,Schima superba,Machilus thunbergii,Diospyros morrisiana,and Michelia maudiae.As the forest in northern Guangdong has developed by succession and protection for a relative long time,the present status of the forest showed the declination of conifers trees and deciduous broad-leaf trees,and provided a foundation for the future development of vegetation typical of ever-green broad leaf forests and its dominant species.The results also provided scientific basis for the construction and sustainable development of nature reserves in northern Guangdong,China.