川西北高寒草甸两种蚯蚓的互作及其对土壤养分的影响

Species Interaction Between Earthworms and Its Effect on Soil Nutrients in an Alpine Meadow, Northwestern Sichuan, China

以川西北高寒草甸中普遍存在的两种蚯蚓（微小双胸蚓Bimastus parvus和威廉腔蚓Metaphire guillemi）为研究对象,采用野外微宇宙实验方法比较单独接种和混合接种时两种蚯蚓的数量、分布和繁殖状况,以及牛粪分解率和土壤养分含量的变化,探讨不同蚯蚓种群间的相互作用及其对土壤养分的影响.结果发现：1）两种蚯蚓混合接种加快了牛粪分解,增加了下层（10~20 cm）土壤可溶性氮含量,但对牛粪分解速率和土壤可溶性氮含量均不存在交互作用;2）在混合接种处理中,微小双胸蚓的死亡比率显著高于威廉腔蚓的死亡比率;3）两种蚯蚓混合接种处理时,威廉腔蚓的繁殖明显受到抑制,而微小双胸蚓的幼蚓数量有所增加.研究表明,威廉腔蚓和微小双胸蚓共存能够发生竞争性相互作用,加快地面上的牛粪分解,增加土壤可溶性氮含量,从而可能提高高寒草甸的初级生产力.

Earthworms are regarded as one of the most important soil macro-invertebrate groups in the terrestrial ecosystem.In order to investigate the interspecific interaction between two earthworm species（Bimastus parvus and Metaphire guillemi） and the associated ecological consequences in an alpine meadow,northwestern Sichuan,China,a field-controlled experiment was conducted including four treatments（two single-species treatments,one mixed-species treatment and one control group without earthworm）.The number of individuals,distribution,reproduction for each species,and the rate of yak dung decomposition and soil nutrient contents for each treatment were examined.It was found that the two earthworm species increased soil dissoluble nitrogen,and accelerated the yak dung decomposition in the mixed-species treatment,but the effect of the interaction between B.parvus and M.guillemi on soil dissoluble nitrogen and yak dung decomposition was not significant statistically.The mortality of B.parvus was significantly greater than that of M.guillemi in the mixed treatment.The presence of B.parvus significantly decreased the reproduction of M.guillemi.Conversely,the latter species might facilitate the reproduction of the former species as reflected by more offspring in the mixed treatment.In general,the competitive interaction between B.parvus and M.guillemi affected their respective population size and reproduction,and increased yak dung decomposition rate and soil dissoluble nitrogen content,which potentially contributed to the high primary production in the meadow.