Selection of mixed species of Casuarina equisetifolia L. based on natural regeneration properties

Based on a field survey of natural regeneration condition in Hainan Casuarina equisetifolia L. coastal protection forest, single objective evaluation methods, respectively taking regeneration quantity, regeneration distribution range and regeneration structure as an evaluation index, and entropy weight comprehensive evaluation method were adopted to evaluate and sort the natural regeneration performance of different tree species under Casuarina equisetifolia forests. Based on the evaluation result, the tree species suitable for natural regeneration under the Casuarina equisetifolia forests were selected. Results showed that tree species with good regeneration ability were Litsea glutinosa (Lour.) C. B. Rob., Acacia auriculiformis A. Cunn. ex Benth, Melia azedarace L., Streblus asper Lour. The small trees are Brucea javanica (L.) Merr., Pandanus tectorius Sol., Polyalthia suberosa (Roxb.) Thw. Shrubs are Atalantia buxifolia (Poir.) Oliv., Murraya koenigii (L.) Spreng., Flacourtia indica (Burm. F.) Merr., and Carmona microphylla (lam.) G. Don. Species with certain regeneration potential included tree species Terminalia catappa L., and Calophyllum inophyllum L.; small trees Mallotus philippensis (Lam.) Muell. Arg. and Premna octonervia Merr. et Metc., and shrubs Clerodendrum inerme (L.) Gaertn. and Psychotria rubra (Lour.) Poir. Small trees and shrubs were the associated species of the coastal protection forests; therefore, proper conservation and planting of these associated tree species should improve species diversity and hierarchy of Casuarina equisetifolia forests. The mixed planting of tree species selected with good natural regeneration in Casuarina equisetifolia forests could help realize the transformation from artificial forest to “near natural” forest.