三江平原碟形洼地中陆栖蚯蚓的分布及影响因素

Distribution of Terrestrial Earthworms and Its Influencing Factors of Saucer Depressions in the Sanjiang Plain

蚯蚓是典型的大型土壤动物,具有重要的生态功能,对环境变化反应敏感。运用样方调查方法,对春季和秋季三江平原蝶形洼地和大豆地中的蚯蚓密度、生物量和种类分布进行了调查,分析了蚯蚓分布与土壤性质之间的关系。结果表明,碟形洼地中的岛状林、灌丛和季节性淹水的小叶章(Calamagrostis angustifolia)沼泽化草甸是蚯蚓的重要生境,共发现陆栖蚯蚓3种,分别为赤子爱胜蚓(Eisenia fetida)、诺登爱胜蚓(Eisenia nordenskioldi nordenskioldi)和哈尔滨爱胜蚓(Eisenia harbinensis),3种蚯蚓都属于正蚓科(Lumbricidae)爱胜蚓属(Eisenia),都为表栖型,5月和9月平均的蚯蚓密度为9~90 ind./m2。碟形洼地中的蚯蚓密度、生物量和多样性都比由湿地开垦的大豆地高;5月(春季)碟形洼地中的蚯蚓密度和生物量都比9月(秋季)高。物种组成上,赤子爱胜蚓是碟形洼地中的优势类群;在大豆地中,已开垦20 a的大豆地中的蚯蚓的优势类群也为赤子爱胜蚓,而在已开垦3 a的大豆地中,哈尔滨爱胜蚓成为优势类群。在碟形洼地中,蚯蚓密度在岛状林、灌丛和小叶章沼泽化草甸中依次递减。生境类型和季节及二者的交互效应对蚯蚓的密度和生物量都有显著影响。淹水水位和土壤水分含量是碟形洼地蚯蚓分布的关键影响因素,同时,蚯蚓分布与土壤总有机碳含量、p H和总氮含量显著正相关。

Earthworm is one typical group of soil macrofauna. The field investigations indicated that the saucer depressions in the Sanjiang Plain, for instance, were excellent habitats for earthworms. The earthworm density, biomass and species in the saucer depressions were studied by quadrate investigation in September 2014 and May 2015, respectively. There were 3 species of earthworm in total in the Calamagrostis angustifolia marshy meadow in the saucer depressions, including Eisenia fetida, Eisenia nordenskioldi nordenskioldi, and Eisenia harbinensis. All of the these species were epigeic, belonging to Lumbricidae, Eisenia, and mean density of earthworm in the 3 sample areas in May 2015 and September 2014 ranged from 9-90 ind./m2. The density, biomass as well as richness of earthworms in the saucer depressions showed much higher than those in the reclaimed soybean fields. As the soil water content increased from the edge to the center of the saucer depressions, earthworm density decreased in turn in the island forest, shrub, Calamagrostis angustifolia marshy meadow. The earthworm density and biomass were higher in spring than those in autumn. Eisenia fetida and Eisenia harbinensis were the dominant species in the saucer depressions and soybean fields reclaimed for 20 years, respectively. Furthermore, soil water content was the main factor to influence earthworm distribution, while the earthworm density positively correlated to the content of total organic carbon, p H of the soil; the earthworm biomass positively correlated to the contents of total organic carbon, total nitrogen of the soil.