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AN ECOLOGICAL STUDY ON ECOSYSTEM FUNCTION OF JAPANESE MEGASCOLECID EARTHWORMS IN FOREST SOILS

森林土壤中日本巨蚓生态系统功能的生态学研究

基本信息

批准号：
14560117
负责人：
KANEKO Nobuhiro
金额：
$ 2.69万
依托单位：
FACULTY OF ENVIRONMENT AND INFORMATION SCIENCES, YOKOHAMA NATIONAL UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Megascolecid earthworms are dominant in Japanese soil, however there are very few studies on lice history and ecosystem function of megascolecid earthworms. We investigated life history of dominant earthworms at two forest sites in Kanagawa Pref. Epigeic species had annual life cycle ; they over wintered as eggs and grew quickly from June to July, then reproduced died in summer. Whereas endogeic species had longer life history and over wintered as juveniles and adults, and reproduction was observed during early summer to autumn. At Tomakomai Experimental Forest of Hokkaido University, epigeics were Megescolecidae, and endogeic species was Lumbricidae. Life history pattern was similar to that of Kanagawa. Carbon and nitrogen isotope ratio of earthworms, litter, soil were measured at forest soils in Hokkaido, Kanagawa and northern Okinawa. Both C and N stable isotopes were enriched from litter to deeper soil. Earthworm isotope rations were correlated to life history ; epigeics showed lighter and endogeics showed heavier isotope ration. Amynthas yambaruensis had ligher isotope ration, and this confirmed anecic life history of this species. Enzyme analysis of gut contents and gut wall showed that epigeic tends to have weaker enzyme activities, whereas endogeics have higher enzyme activites suggesting that endogeic earthworms utilize more recalcitrant organic matters in soil.

日本土壤中的蚯蚓以大囊蚴为主，但关于大囊蚴的虱史和生态系统功能的研究很少。本文调查了神奈川县两个林区优势种蚯蚓的生活史，结果表明，优势种蚯蚓的生活史以年为周期，以卵越冬，6 ~ 7月生长迅速，夏季繁殖死亡。内生种的生活史较长，以幼、成虫越冬，繁殖期在初夏至秋季。在北海道大学的Tomakomai实验林中，表生种为Megescolecidae，内生种为Lumbricidae。生活史模式与神奈川相似。测定了北海道、神奈川和冲绳北方森林土壤中蚯蚓、凋落物和土壤的碳、氮同位素比值。C和N稳定同位素从枯枝落叶层向深层土壤富集。蚯蚓的同位素比值与生活史相关，表生体的同位素比值较轻，内生体的同位素比值较重。羊八井远环蚓的同位素组成较轻，证实了该物种的生活史。肠内容物和肠壁的酶分析表明，表生蚯蚓的酶活性较弱，而内生蚯蚓的酶活性较高，这表明内生蚯蚓利用更多的难消化有机质。