Community Species Structure Characteristics of Four Types of Keteleeria cyclolepis Natural Forests in Fujian Province

Community species structure characteristics of four types of Keteleeria cyclolepis natural forests in Fujian Province, i.e., K. cyclolepis forest, K. cyclolepis＋Castanopsis eyrei forest, Keteleeria cyclolepis＋Cyclobanopsis gilva forest, and Keteleeria cyclolepis＋Phyllostachys pubesces forest, were investigated and analyzed by means of typical square sampling method. The results showed that there were two sublayers in the arbor tree layer in all of the four types of Keteleeria cyclolepis natural forests, while K. cyclolepis mainly occupied the upper part of the arbor tree layer, growing with 16 companion tree species. There were 10 tree species from the community building families of the broadleaved subtropical evergreen forests including Fagaceae, Lauraceae, Magnoliaceae and Theaceae among the companion tree species, accounting for 62.5% of the total. There were 26 species in the shrub layer of different types of the natural forests, among which 9 shrub species were from the families of Lauraceae, Magnoliaceae and Theaceae, accounting for 34.6% of the total. There were 7 species respectively in the herb layer and the interlayer of the vegetation. There were not much differences in the species composition in the shrub and herb layers in different types of the natural forests, but the dominant species in the shrub and herb layers in different types of the natural forests were quite different. The dominant species in shrub layer and herb layer of Keteleeria cyclolepis forest were Itea chinensis and Woodwardia japonica respectively. Asidosasa notata and Rhododendron henryi were the codominant species in shrub layer, whereas Dicranopteris dichotoma was the dominant species in the herb layer of Keteleeria cyclolepis＋Cyclobanopsis gilva forest type. Rhododendron ovatum and Eurya alata were the codominant species in the shrub layer of Keteleeria cyclolepis＋Castanopsis eyrei forest and Keteleeria cyclolepis＋Phyllostachys pubesces forest types. Dicranopteris dichotoma and Lophatherum gracile were the codominant species in herb layer of Keteleeria cyclolepis＋Castanopsis eyrei type, while Woodwardia japonica was the dominant species in herb layer of Keteleeria cyclolepis＋Phyllostachys pubesces forest type. The study showed that Keteleeria cyclolepis failed to naturally regenerate well because of the high coverage of shrub and herb layers, where the Keteleeria cyclolepis saplings were often replaced by evergreen broadleaved tree species.