ABSTRACT Introduction. The Kuril Islands Chain demarcates the boundary between the circumpolar and East Asian floras in the amphi-Pacific and is a trans-Oceanic migration route from warm-temperate insular East Asia to north-east Asia and Beringia. This paper reviews the flora of the northern part of Iturup Island in regards to its bryogeography and taxonomic diversity, as well as its relative position among other bryophyte floras of north-east and East Asia. Methods. The paper uses morphological methods to identify the species composition and detrended correspondence analysis to identify the position of the northern Iturup Island in the system of local floras of the eastern, extra-tropical, Pacific. Key results. The flora is closely related to the bryophyte floras of the southern Kurils and Hokkaido Island, but has been found to be distinctly distant from the ‘true’ cool-temperate East Asian floras, as well as from the boreal and hemiarctic floras of north-east Asia. Instead, the floras of the south Kurils and northern Hokkaido Island belong to a peculiar intermediate phytogeographic province that cannot be unambiguously placed in either the East Asian or circumboreal floristic regions. The hemiboreal character of the bryophyte flora of northern Iturup Island is in contrast to the general appearance of many of the dominant vegetation communities on the island, which are more characteristic of the hemiarctic. Conclusion. There is no robust evidence to refer the bryophyte flora of northern Iturup either to the circumboreal or East Asian Floristic Region, the flora belongs to a unique intermediate province between the two regions.

中文翻译：

---

伊图鲁普北部（西北太平洋）的苔藓植物区系：介于北方和东亚植物区系之间

摘要介绍。千岛群岛链划定了两栖太平洋的环极区和东亚区系之间的边界，是一条从暖温带东亚岛国到东北亚和白令岛的跨洋迁徙路线。本文综述了伊图鲁普岛北部植物群的苔藓地理和分类多样性，以及它在东北亚和东亚其他苔藓植物区系中的相对位置。方法。本文采用形态学方法确定物种组成和去趋势对应分析，确定北部伊图鲁普岛在东部、热带、太平洋地方植物群系统中的位置。关键结果。植物区系与南千岛群岛和北海道的苔藓植物区系密切相关，但已发现它与“真正的”冷温带东亚植物群以及东北亚的北方和半北极植物群明显相距甚远。相反，南千岛群岛和北海道岛北部的植物群属于一个特殊的中间植物地理省，不能明确地置于东亚或环北植物区系。伊图鲁普岛北部苔藓植物群的半北特征与岛上许多优势植被群落的总体外观形成对比，后者更具有半北特征。结论。没有强有力的证据表明伊图鲁普北部的苔藓植物区系属于环北方或东亚植物区系，植物区系属于这两个地区之间的一个独特的中间省。