Abstract: Luozha River is a first branch of Lancang River in its middle section . A less known deciduous monsoon forest was recently discovered on the dry-hot banks of Luozha River. The deciduous monsoon forest is 15 - 20m tall with Lannea coromandelica、Colona floribunda、Mallotus philippensis as the dominant tree species, and Microstegium ciliatum、Eupatorium odoratum、Ageratum conyzoides are the dominant species in the shrub-herb layer . The species richness is higher in the shrub-herb layer than in the tree layer .Most of the trees have DBH ( diameter breast height) between 5 - 10 cm, and
big trees with large DBH are fewer .Compared with the tropical montane rain forest and the evergreen broad-leaved forest in southern Yunnan , the deciduous monsoon forest has lower species richness index than the tropical montane rain forest , but close to the monsoon evergreen broad-leaved forest .

Key words: Deciduous monsoon forest

摘要： 对罗扎河下游鲜为人知的落叶季雨林进行了群落生态学研究, 结果表明: 罗扎河下游落叶季雨林群落高度在15～20m 之间; 群落乔木层以厚皮树( Lannea coromandelica) 、一担柴( Colona floribunda)、粗糠柴( Mallotus philippensis)、毛果扁担杆( Grewia eriocarpa) 、灰毛浆果楝( Cipadessa cinerascens) 等树种为优势种;灌草层以刚莠竹( Microstegium ciliatum) 盖度最大, 其余如飞机草( Eupatorium odoratum)、藿香蓟( Ageratum conyzoides) 、蹄盖蕨( Athyrium sp .) 等种的盖度也比较大; 群落中乔木和附生、藤本植物种类较少, 而灌木和草本植物种类较多; 多数乔木层植株胸径在5～10 cm 之间, 大径级乔木比较少, 即使群落中的优势种也主要是通过较多数量的中小径级个体体现出来。多样性指数计算表明, 本落叶季雨林的生物多样性指数虽然比典型热带山地雨林为低, 但大致相当于季风常绿阔叶林。

关键词: 落叶季雨林, 群落生态学, 罗扎河, 云县