Abstract:

Objective: The community structure and diversity of arbor species in unmanaged Phyllostachys edulis forest (old and dead bamboos were removed without other reclamation interference) with low ecological function were studied, aiming to provide a basis for making scientific tending measures and promoting the succession of the unmanaged P. edulis forest to the mixed forest of bamboo and tree. Method: Two types of unmanaged(8 a and 20 a)P. edulis forests were chosen in Changshan County, southwest Zhejiang Province. The sample plot survey method was used and 3 sample plots in size of 20 m × 20 m were set in each type of P. edulis forests. The composition and quantity of P. edulis and arbor species in each type of the P. edulis forests were investigated. The importance value, community similarity coefficient and common biodiversity were used to analyze the arbor species composition, community structure and diversity of two types of the P. edulis forests. Result: The total number of living trees in the P. edulis forest unmanaged for 20 a were significantly higher than that in the P. edulis forest unmanaged for 8 a, with an increase of 245.9%. There were 14 species and 10 families such as Fagaceae and Theaceae in the P. edulis forest unmanaged for 8 a, the dominant species was Lithocarpus harlandii. There were 14 species and 7 families such as Fagaceae and Theaceae in the P. edulis forest unmanaged for 20 a, the dominant species was Schima superba. With the increasing number of unmanaged years, the important values of S. superba, L. glaber and Castanopsis sclerophylla in the community increased significantly and gradually occupied a dominant position in the tree community, while the important values of Quercus serrata and Machilus thunbergii decreased significantly. Compared with the P. edulis forest unmanaged for 8 a, the proportion of arbor species with height of 2.0 m and above and ground diameter of 2.1 cm and above in the P. edulis forest unmanaged for 20 a increased significantly, and Fagaceae species such as L. glaber and C. sclerophylla were better in height growth and radial growth. The diversity characteristics of arbor species in different succession stages were quite different. With the increase of the number of unmanaged years, the richness and diversity of arbor species in tree layer were significantly improved, and the diversity index of arbor species in shrub layer was not significantly different; The species richness and diversity of arbor species in herb layer decreased significantly. Conclusion: The dominance of arbor species in the forest increased in the natural succession process of the unmanaged P. edulis forest. The arbor species such as S. superba and L. glaber gradually dominated in the arbor species community in southwest Zhejiang Province. Some recommended precious tree species in Zhejiang (such as M. thunbergii and Cyclobalanopsis gracilis) have no obvious competitive advantage in the unmanaged P. edulis forest. In order to promote positive succession of bamboo-tree mixed forest to evergreen top community and the ecological function of the unmanaged or even abandoned P. edulis forest, it is necessary to carry out appropriate manual measures such as remove old and dead bamboo, reduce the density of bamboo, and carry out positive intervention on target or precious tree species.

Key words: out-of-management Phyllostachys edulis forest, succession, arbor, species diversity