Status of Tilia maximowicziana (Malvaceae s.l.) in Russia

Abstract

Tilia maximowicziana (Malvaceae) is a plant species endemic to the northern part of the Japanese archipelago and Kunashir Island. In Russia, this species is included in the Red Data Book of the Russian Federation with rarity category 1 (taxon near extinction). In 2014–2019, we conducted field surveys of known Tilia maximowicziana subpopulations in Russia. We found and considered six locations on Kunashir Island. We further estimated morphometric traits of individuals and vegetation characteristics. On the basis of obtained data, we conducted regional IUCN estimation of T. maximowicziana for the Russian territory. We found that T. maximowicziana subpopulations inhabited deciduous and mixed forest plant communities, where Sasa sp. plants dominated in the herb layer. We demonstrated that the endemic plant species represented lower values of DBH and tree height, while leaf size (length / width), length of petioles and fruits were within the amplitude of their values known in the main part of the species range. According to IUCN Red List categories, T. maximowicziana has the regional status CR B1ab(iii); C2a(i); D in Russia. The findings of fruit production in a T. maximowicziana subpopulation demonstrated the ability to seed reproduction of this species in northern limit of the natural range. The obtained results allowed us to estimate the global IUCN status of T. maximowicziana, taking into account its subpopulations in the Japanese archipelago.

Keywords

• endemic
• fruit production
• iucn red list
• morphometric traits
• plant community
• range
• threat