日本冲绳岛琉球松林台风干扰后的群落特点

Community Characteristics of Pinus luchuensis Forests after Typhoon Disturbance in Okinawa Island, Japan

为阐述亚热带地区琉球松林受到干扰后的演替规律,就日本冲绳地区琉球松人工林在强台风干扰后,林分结构和树种组成特点进行了调查分析。结果表明,琉球松林经台风干扰后演替形成两种群落类型,即琉球松-峨嵋木荷群落和琉球松-峨嵋木荷-蕨类群落;两者在林分结构和树种组成特点方面差异明显。琉球松-峨嵋木荷群落中,出现乔灌树种26种(DBH≥3.0cm),树种多样性指数为2.55,林下植被特别是草本层盖度低,没有蕨类植物分布。而琉球松-峨嵋木荷-蕨类群落中,出现乔灌树种33种,树种多样性指数为3.51,林下植被特别是草本层发育较好,并有大量蕨类植物分布,其盖度达55%。此外,经受干扰的琉球松林出现了大量的较耐荫的常绿阔叶树种,尤其是山茶科和樟科的树种,而没有出现本地天然常绿阔叶林的优势树种壳斗科的栲类(Castanopsisspp.)。充分说明强台风干扰促进了琉球松林向常绿阔叶林演替。

To clarify the succession of pine forests on Okinawa Island, Japan after typhoon disturbance, the stand structure and species composition of Pinus luchuensis (Luchu pine) forests affected by typhoon disturbance were studied.Based on species composition and stand structural traits,pine forests could be classified into two community types: Pinus luchuensis-Schima wallichii community,and Pinus luchuensis-Schima wallichii-Cyathea community. There was thus no clear difference in the severity of the disturbance. The diversity index of tree species and the number of species ( DBH ≥ 3.0 cm) in Pinus luchuensis-Schima wallichii-Cyathea community were larger (3.51 and 33 species) than those in Pinus luchuensis-Schima wallichii community (2.55 and 26 species).There was significant difference in the development of undergrowth for the two types of the communities.In Pinus luchuensis-Schima wallichii-Cyathea community,the coverage of undergrowth reached 55%, particularly for the appearance of many Cyathea species.However,none of Cyathea species appeared in Pinus luchuensis-Schima wallichii community.Evergreen broad-leaved trees, such as species from Theaceae and Lauraceae were frequently present in the shrub layer, while trees belonging to Fagaceae,such as Castanopsis species were rare in both communities.It demonstrates that the typhoon disturbance can accelerate the succession from pine to evergreen broad-leaved forest in Okinawa.