Vascular plants from Kunashiri Island , the southernmost island of the Kuril Islands , island arc between Hokkaido and Kamchatka peninsula

Vascular plants of the Kunashiri Island, the southernmost island of the Kuril Islands, were inventoried during an expedition to Kunashiri, 19–25 July 2013. This study was conducted as a part of the Sika Deer (Cervus nippon yezoensis) management program in Shiretoko World Natural Heritage Site, to assess vegetation damage under strong browsing pressure by the deer. A checklist of the vascular plants was made from each study locality. As Kunashiri Island is very close to Shiretoko Heritage Site, with similar climatic and geographical conditions, this plant list will provide a preliminary comparison of the floral composition between Kunashiri and Shiretoko or Hokkaido. Our research revealed that vegetation is well preserved on Kunashiri, and this floral list will serve as a reference of the original floral composition of Shiretoko World Natural Heritage Site prior to damage by deer.


INTRODUCTION
Kunashiri is the southernmost island of the Kuril Islands and holds a close floristic relationship with neighboring mainland Hokkaido.The island is considered to have been connected with Hokkaido and Shikotan until after the last glacial period (Melekestsev et al. 1974).The geological environment of Kunashiri resembles that of Shiretoko Peninsula of eastern Hokkaido in its mountainous topology with volcanic activities.The flora of Kunashiri Island has been reported several times (e.g., Miyabe 1890;Matsumura 1943;Tatewaki 1957;Alekseeva 1977Alekseeva , 1983;;Voroshilov 1982;Barkalov 1980Barkalov , 2009; see Takahashi 1997 for details); these reports were integrated in a recent publication by Barkalov (2009).However, in these studies, the flora and vegetation of the island are often treated as a part of the Kuril Islands or the Sakhalin region of mainland Asia (Russia).In order to better understand the flora and vegetation of the Kunashiri, comparisons of floristic composition with Shiretoko or Hokkaido are also necessary, and as species concepts employed by Russian taxonomists sometimes differ from that of Japanese taxonomists, such comparisons are helpful to remedy this situation.To do this, thorough comparisons in both areas of the floral composition in each major vegetation types are needed.
This assembled check list is the result of a vegetation study undertaken as a part of the Sika Deer management program in Shiretoko World Natural Heritage Site.Sika Deer are native to most areas of Japan, from Hokkaido to Yakushima Island of Kyushu, with their numbers having notably increased from 1970 onwards in Shiretoko.On the other hand, Sika Deer are absent from Kunashiri, or at least have not been recorded here until now (Hokkaido Regional Forest Office, Kushiro Branch 2012).The specific objective of the study was to assess the recovery of damaged vegetation under strong browsing pressure by the deer.As a result, a vegetation classification of each locality accompanies our check list.Descriptions of the floristic composition of vegetation was reported, for example, by Tatewaki and Hirano (1936) for Picea glehnii forest of Furukamappu (Yuzhno-Kurilsk), and such descriptions are useful for comparison to the floral composition on Kunashiri and Hokkaido.Our check list will also provide a reference on the original flora and vegetation of Shiretoko World Natural Heritage Site before damage by the deer.

MATERIALS AND METHODS
The studied localities are indicated in Figures 1 and 2 and Table 1.All the sites are located in the south part of the island.Their ecological characteristics are as follows: 1) Andreevka is located at the Pacific coast, and the plant co mmunities of this locality, including coastal grassland, meadow and coniferous forest, are mostly secondary succession; 2) Mount Tomari is characterized by a wider variety of plant communities than other localities, ranging from coastal grassland along the Okhotsk Sea to mountain hardwood and/or coniferous forests around the pass of the Mount Tomari caldera, with volcanic solfataras vegetation (vegetation affected by sulfurous gases of    Trail are mountain hardwood and/or coniferous forests.In addition to these, coastal grassland is distributed along the Okhotsk Sea and solfataras are also observed in the middle part of the trail; 4) Furukamappu Bog is located in northwest part of Yuzhno-Kurilsk and consists of well preserved bogs dominated by Sphagnum spp.Picea glehnii forest, one of the most common forests on perhumid (ever-wet) sites in south Kuril and Hokkaido, is also developed in the bog.
These localities were surveyed by four authors (all except V. Yu.Barkalov).The study was mainly performed at designated vegetation study sites, but was also conducted along the trail between these sites.On average, time for floral study was one to two hours in each locality.Red data plants were not collected, as far as we could determine.Species names followed Yonekura and Kajita (2003).All collected specimens were identified by the authors, mainly by V. Yu.Barkalov, according to the APGIII system (Yonekura and Murata 2013)
In Furukamappu Bog (4a) we found rare plants such as Pogonia japonica Rchb.f. and Eleorchis japonica (A.Gray) F. Maek., and also many species of Carex, which are Red Data list plants in Japan (2012).

DISCUSSION
We observed Sasa senanensis (Franch.& Sav.) Rehder and Sasa nipponica (Makino) Makino & Shibata largely covering the coniferous forest floor.Along with Sasa, forest floors were sometimes covered with Dryopteris expansa (C.Presl) Fraser-Jenk.& Jermy, as also seen in some Abies-Picea forest of Shiretoko (e.g., Cape Shiretoko, Teppanbetsu; Samejima et al. 1981).Recently, Sasa has been reduced in the forests of Shiretoko because of browsing damage by Sika Deer.Along the trail where Sasa or Dryopteris are rather rare, we noticed plants such as Adoxa moschatellina L. (whose level of extinction risk classification has increased due to browsing damage by Sika Deer in Kyoto (Kyoto Prefecture 2013)), Orthilia secunda (L.) House, Carex sachalinensis F. Schmidt and others.It will be necessary to investigate how these plants grow in the forests of Shiretoko under the browsing pressure of Sika Deer.
The southern Kuril Islands of Kunashiri and Etorofu constitute a distribution limit of some warm to temperate plant elements, which tend to occur along the Okhotsk Sea coast due to warmer climatic conditions than the Pacific coast (Barkalov 2009).Some of these plants are classified as red data plants for Russia and the Sakhalin region.We found Magnolia obovata Thunb.and Quercus dentata Thunb. in good condition, and Aralia cordata and Hydrangea petiolaris Siebold & Zucc.were observed several to many times.However, we did not observe Cercidiphyllum japonicum Siebold & Zucc.and Tilia maximowicziana Shirasawa, which are considered very rare in Kunashiri (Barkalov 2009), although Cercidiphyllum japonicum and Tilia maximowicziana are common in Shiretoko (Samejima et al. 1981).As far as was observed in this study, hardwoods (broadleaved trees) of warm-temperate elements were mainly dispersed among coniferous forests, and their distribution seems to be more limited in Kunashiri than in Shiretoko.
The central site of volcanic activity in the caldera of Mount Tomari was surrounded by thickets of Pinus pumila and Ledum palustre, with Empetrum nigrum L. var.japonicum K. Koch and Spiraea betulifolia Pall.var.betulifolia.Sato (1981) reports the Miscanthus community from a new volcano site of Mount Io-zan, Shiretoko, and also observed the occurrence of Pinus pumila with Empetrum nigrum, despite of the low altitude of the region.Furukamappu Bog is a species-rich sphagnum bog.Though the bog differs from bogs in Shiretoko, occurring among mountains, these sphagnum bogs are widely seen in Hokkaido, and it will be interesting to compare species composition between these bogs.

ACKNOWLEDGEMENTS
This study was arranged in the visa-free exchange programs between Japan and Russia, and we are grateful for the support of all the organizations in charge in both countries, especially for Ministry of Foreign Affairs, Ministry of the Environment, Northern Territories Issue Association and Marine Wildlife Center of Japan.This study was partly supported by JSPS KAKENHI Grant no.25292085 to Koichi Kaji, Tokyo University of Agriculture and Technology.

Figure 1 .Figure 2 .
Figure 1.Map of Kunashiri Island with studied localities.The labelled sites correspond to Tables1 and 2 and Figure 2.
also developed in and around the caldera;3) The common plant communities of Stolbovskyy Ecological
are very similar to those of Shiretoko or Hokkaido, except for the presence of Sasa, which widely covers the forest floor.The composition of coniferous forests was similar to those in Hokkaido, containing plants such as Cornus canadensis L., Maianthemum dilatatum (A.W. Wood) A.