「森林総合研究所研究報告」（Bulletin of FFPRI）Vol.18-No.3（ No.451）275-288 September 2019 275 Bulletin of the Forestry and Forest Products Research Institute 論 文（Original article） Vol.18 No.3 (No.451) September 2019 Current distribution and climatic range of the Japanese endemic conifer CONTENTS Thuja standishii (Cupressaceae) Original article James R. P. Worth1)* Current distribution and climatic range of the Japanese endemic conifer Thuja standishii (Cupressaceae) Abstract James R. P. Worth ……………………………………………………275 Thuja standishii (Gordon) Carr. (Cupressaceae) is an important endemic conifer of Japan but unlike other endemic Cupressaceae species there is a general lack of information about the species including its current distribution, ecology and conservation status. This study investigated the geographic range of the species and evaluated the number of recent Temporal and regional variations of drought damage at private planted forests in population extinctions using available published and online resources along with field based investigations. Additionally, the species potential range was investigated using species distribution modelling. Thuja standishii was found to have Japan based on 36-year record of statistical data a wide range in Japan from 40.67˚ N in northern Honshu to 33.49˚ N in Shikoku occurring across a variety of habitats Natsuko YOSHIFUJI, Satoru SUZUKI and Koji TAMAI ……………289 from warm temperate evergreen forest to near the alpine zone. The core of its range is in central Japan including in both high and low snow-fall mountain regions. On the other hand, the species is extremely rare in western Japan being confirmed at only eight locations including five sites in Chugoku and three in Shikoku. These include the most extreme Residual disturbances in soil physicochemical properties following scarification in warm-edge populations known in the species that were poorly predicted by the whole range species distribution model. regenerated birch forests in Hokkaido, northern Japan. These populations are of great conservation significance and either represent long term persistence in refugia isolated from the species core range in central Honshu or remnants of a formerly more widespread occurrence in the warm Eriko ITO, Toru HASHIMOTO, Shuhei AIZAWA, temperate zone of western Japan lost over millennia to human activity. Overall, the species population trajectory Naoyuki FURUYA and Satoshi ISHIBASHI …………………………301 appears to be stable with evidence for three population losses only that occurred in the mid-20th century. Key words: climate relicts, conservation, Japanese endemic conifer, range-losses, rear-edge population, species Short communication distribution model, Thuja standishii Vegetation dynamics in clearcut sites with deer fencing and culling of sika deer Atsushi SAKAI, Tatsuya OTANI, Kazuki MIYAMOTO, Chizuru YAYOTA and Sakae FUJII …………………………………311 1. Introduction studied (Yang et al. 2009, Liu et al. 2013, Tang et al. 2015, The genus Thuja L. (Cupressaceae) contains five extant Hou et al. 2018). By contrast, Thuja standishii has received Allactoneura akasakana Sasakawa, 2005 (Diptera, Mycetophilidae), occurred in species including three in East Asia and two in North America little research attention with basic information on the limits of (LePage 2003). The genus likely evolved around 60 million its geographical range, reproductive biology, impact of past cultivation facilities of shiitake mushroom years ago at high latitudes in North America with the oldest logging and phylogeography lacking. This general paucity of Masahiro SUEYOSHI, Hiromi MUKAI, Hiroshi KITAJIMA unambiguous Thuja fossil from the Paleocene (66 to 55 million knowledge of the species is exemplified by the fact unlike the and Junhao HUANG …………………………………………………319 years ago) of the Canadian Arctic (Cui et al. 2015). From its other two Asian species the overall population trend is classified Arctic origin, Thuja is thought to have expanded its geographic as unknown (Carter and Farjon 2013). Research record range southwards reaching East Asia in the Miocene (Peng and Thuja standishii (kurobe or nezuko in Japanese and Japanese Sexual size dimorphism and seasonal changes in the body size of bats captured in Wang 2008). The three extant species of Thuja in East Asia are arbor-vitae in English) is distributed on the islands of Honshu Hitsujigaoka, Sapporo, Hokkaido, Japan. geographically restricted with Thuja koraiensis Nakai found and Shikoku and across its range can grow as a multi-stemmed in mountainous areas of the Korean Peninsula and Changbai shrub under 1m tall to a tree 35 m in height (Eckenwalder 2009) Hirofumi HIRAKAWA ………………………………………………325 Mountain, China, Thuja sutchuenensis Franchet is confined to (Fig. 1). The species can purportedly reach a great age with the Daba Mountains of southwest China and Thuja standishii trunks reaching up to 3 m in diameter (http://www.rinya.maff. Flora list of wild plants in Shikoku Research Center, Forestry and Forest Products (Gordon) Carr. is endemic to Japan. All three Asian species go.jp/tohoku/introduction/gaiyou_kyoku/annai/midokoro/ Research Institute – 2019 revised edition are of conservation concern due to past logging with Thuja midokoro_sennenkurobe.html). It is most closely related to the Atsushi SAKAI ………………………………………………………333 sutchuenensis classified as Endangered, Thuja koraiensis as Chinese endemic Thuja sutchuenensis while the geographically Vulnerable and Thuja standishii as Near Threatened (IUCN closest member of the genus, Thuja koraiensis, is phylogenetically Red List of Threatened Species; www.iucnredlist.org). The closer to the North American Thuja plicata (Li and Xiang 2005). distribution, ecology and genetic diversity of both Thuja Macrofossil evidence shows that Thuja standishii has occurred sutchuenensis and Thuja koraiensis have been relatively well continuously in Japan for at least the past four million years Received 22 November 2018, Accepted 25 February 2019 1) Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute (FFPRI) * Department of Forest Molecular Genetics and Biotechnology, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687 JAPAN; e-mail: [email protected] 276 James R. P. Worth Fig. 1. Thuja standishii in its natural habitat. (a) Single stemmed individual (centre) in warm temperate evegreen forest at Mt. Hanataka at 515 m a.s.l., Shimane Prefecture; (b) T. standishii dominated forest on limestone at Monobe Valley (590 m a.s.l.), Kouchi Prefecture; (c) A large multi-stemmed individual in rocky Tsuga diversifolia dominated subalpine forest at 2050 m a.s.l. in the Yatsugatake Mountain Range; (d) Close up of the foliage and immature female cones of T. standishii at 520 m a.s.l. on Washigamine Peak, Dogo Island, Shimane Prefecture; (e) Short multi-stemmed thicket of T. standishii with Pinus parviflora at Sanpouiwa Peak (1700 m a.s.l.), Gifu/ Ishikawa Prefecture border; (f) Tall single stemmed mixed forest of T. standishii (centre and right) and Chamaecyparis pisifera (left) at Atebi Daira (1200 m a.s.l.), Nagano Prefecture. (Momohara 2016) and that it occurred near sea level during the plantation conifers Cryptomeria japonica and Ch. obtusa. colder and drier Last Glacial Maximum in Tohoku (Suzuki In central Honshu and Tohoku, Thuja standishii is known to 1991) and the Japan Sea side of Honshu (Kamoi et al. 1988) as occur in mountainous areas where it grows in coniferous forest part of the subalpine conifer forests that dominated Honshu in with almost all conifer species that are found within its range lowland areas at this time (Takahara et al. 2000). (Debreczy et al. 2011) including Ch. obtusa, Ch. pisifera, Cr. In Japan, Thuja standishii is rarely used in cultivation and has japonica, Pinus parviflora, Sciadopitys verticillata, Tsuga undergone little selection of cultivars (Eckenwalder 2009) unlike diversifolia and Thujopsis dolabrata. At higher altitudes the the two North American species. The species is also not used in species forms part of the subalpine vegetation to 2400 m in plantations probably because of its slow growth (Debreczy et al. elevation around the edges of rocky summits, near lakes and on 2011) and its wood quality does not surpass that of the widely highland moors (Kurata 1971) (Fig. 1e). The species is resilient planted Japanese cypress (Chamaecyparis obtusa) (Nakagawa to snow and is common in the snowy mountains on the Japan 1994). However, the wood is resistant to decay (Hirose et al. Sea side of Honshu forming an important part of upper subalpine 1968) and in the past has been prized for use in ceilings, fanlights forests (Gansert 2004). However, the species is extremely rare and furniture (Kurata 1971). Wood artefacts from the Edo Period in western Japan with records from the Kii Peninsula, Chugoku of Tokyo show that it was used for coffins (Suzuki and Noshiro and Shikoku only (Hayashi 1960) but its distribution in these 2006), stakes, furniture (Matsuba 1999) and sewer construction areas is poorly understood. For example, in Shikoku, Hayashi (Suzuki and Noshiro 2008) but was always a very minor species (1960) mapped the species as occurring in five areas but only compared to other conifers (Matsuba 1999, Suzuki and Noshiro two of these (Mt. Higashiakaishi and Monobe Valley) are 2008). Overall, the rarity of forest dominated by Thuja standishii confirmed by vegetation mapping (Biodiversity Center of and its insignificant role in forestry probably underlies the lack Japan, http://www.biodic.go.jp).