西双版纳热带次生林和橡胶林蚯蚓数量分布及其与环境因子的关系

Quantitative distribution of earthworms and its relationships with environmental factors in tropical secondary forest and rubber plantation in Xishuangbanna

2006年1月,通过样地调查法比较了西双版纳次生林和橡胶林2种不同土地利用方式的蚯蚓数量分布状况及其与环境因子的关系。结果表明:自然林转变为橡胶林后,土壤养分及植物有机碳输入均明显减少,同时蚯蚓群落发生较大的变化:在橡胶林,热带外来种蚯蚓无围海蚓的密度(52.27ind.m-2)显著高于林地内本地种蚯蚓远环蚓的密度(0.53ind.m-2),但在次生林,2种蚯蚓的密度和生物量无显著差异;橡胶林本地种蚯蚓远环蚓的密度(0.53ind.m-2)和生物量(0.32g.m-2)与次生林(6.93ind.m-2、7.76g.m-2)相比呈下降趋势。无围海蚓的幼蚓在其种群中占有较大比例,类似增长型种群年龄结构,而远环蚓则主要以成蚓为主。相关分析表明,橡胶林的细根生物量与无围海蚓的密度呈显著正相关。由此预示蚯蚓群落结构的这种变化可能与橡胶林土地利用引起的植被变化、土壤养分下降等因素密切相关,同时外来种蚯蚓与本地种蚯蚓本身的生态适应对策也不可忽视。

To understand the influence of land use change on earthworm communities, the quantitative distribution of earthworms and its relationships with environmental factors in the tropical secondary forest and rubber plantation in Xishuangbanna, Southwest China were studied in January 2006. The results showed that after the secondary forest converted into rubber plantation, soil nutrients and organic C input from plants reduced significantly, and earthworm communities altered. In rubber plantation, the density of tropical exotic earthworm （Pontoscolex corethrurus ） （52.27 ind ·m^-2） was significantly higher than that of native earthworm （Amynthas sp. ） （0. 53 ind ·m^-2 ） ; while in secondary forest, no significant differences were observed in the density and biomass of the two earthworm species. The density （0. 53 ind ·m^-2） and biomass （0.32 g ·m^-2 ） of Araynthas sp. in rubber plantation showed a decrease trend compared with those in secondary forest （6. 93 ind ·m^-2, 7. 76 g ·m^-2）. An inereasing population of P. corethrurus was accounted by the larger proportion of its juvenile＇ s density and biomass, while Amynthas sp. was mainly composed of adults. The fine-root biomass of rubber plantation was positively eorrelated with the density of P. corethrurus. It was suggested that the vegetation change and soil nutrient decrease due to the conversion of secondary forest into rubber plantation had promoted the reproduction of exotic earthworm, and the adaptive strategies of exotic and native earth- worms could not be ignored.