Earthworms contribute to the sustainability of food webs in the semi-natural grasslands of levees at paddy margins, which are typical components of satoyama, the traditional agricultural landscapes of Japan. Thus far, few studies have focused on earthworm fauna of paddy levees in satoyama. In this study, we investigated earthworm fauna and regional and monthly changes in earthworm density. We found at least 11 species of earthworms living within levees on Sado Island, central Japan. Two endogeic species, Amynthas corticis (Megascolecidae) and Eisenia japonica (Lumbricidae), were dominant in terms of number of adult individuals; these two species appeared in all study regions. We also estimated an average of ~57.4 individuals/m2 for all stages of earthworms in levees, suggesting that rice paddy levees have relatively-high earthworm density. However, such tendencies differed depending on the region. In addition, monthly changes in density were observed in the topsoil of the levees. Our results imply that differences in earthworm assemblages amongst regions and months may influence the availability of food resources for various animals inhabiting satoyama.

中文翻译：

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日本里山稻田堤上半天然草原的species种类和密度

lev为稻田边缘的堤坝半天然草原中食物网的可持续性做出了贡献，稻田是日本传统农业景观-佐山的典型组成部分。迄今为止，很少有研究集中在里山稻田的worm动物区系。在这项研究中，我们调查了fauna的动物区系以及regional密度的区域和每月变化。我们在日本中部佐渡岛的堤坝中发现了至少11种species。就成年个体的数量而言，两种内生物种，即Amynthas corticis（Megascolecidae）和Eisenia japonica（Lumbricidae）占优势。这两个物种出现在所有研究区域。我们还估计，堤防中各个阶段的an平均约为〜57.4人/ m2，这表明稻田堤防中的density密度相对较高。然而，这种趋势因地区而异。此外，在堤防表层土壤中每月都观察到密度的变化。我们的结果表明，不同地区和月份之间worm组合的差异可能会影响居住在里山的各种动物的食物资源的可用性。