Pinus amamiana (ヤクタネゴヨウ, Yakushima white pine) description

Pinus amamiana

Koidzumi 1924

Common names

ヤクタネゴヨウ, amami-goyomatsu, Yakutane-goyo, Amami-goyo [Japanese]; Yakushima white pine (Koidzumi 1924, Takehara 1976).

Taxonomic notes

Syn. Pinus armandii var. amamiana (Koidzumi) Hatus. 1974. Commonly treated under this name, but now accepted as a distinct species (Farjon 1998), allied not to P. armandii but to P. morrisonicola and P. parviflora (Frankis 1989). Genetic studies by Kanetani et al. (2004) have found no differences in diversity between the two populations on Yakushima and Tanegashima Islands. This is interesting because the species has nearly been extirpated on Tanegashima, and the high level of diversity indicates that the population decline happened in the recent past (corroborated by historical data discussed under Ethnobotany).

For discussion of systematics relative to other species in subsection Strobus, see Phylogeny of East Asian white pines.

Description

Trees up to 30 m tall and 200 cm dbh. Bark gray-brown, smooth, with age turning gray-black and peeling in thin scales. Branchlets gray-brown, puberulent soon turning glabrous. Cataphylls imbricate, membranaceous, ovate to broad-linear, 2-7 × 1.5 mm, red-brown, deciduous. Needles 5 per fascicle, 30-80 × 0.8-1.0 mm, stomata on two inner faces only, resin canals 3 (2 abaxial, marginal; 1 adaxial, median). Cones on short peduncles, ovoid, red-brown, 5-7 × 3-4 cm. Cone scales woody, obovate-orbicular, 1.5-2.0 × 2-3 cm. Seeds gray-black, 10-12 × 4-6 mm, with a rudimentary wing 0.5-1 mm long (Koidzumi 1924, Takehara 1976, Iwatsuki et al. 1995, M.P. Frankis obs. of herbarium material at Kew, 1999).

Flowering occurs in May; cones ripen in October of the following year (Iwatsuki et al. 1995).

Similar species: P. amamiana differs from P. armandii in having shorter leaves and smaller cones. It differs from P. armandii var. mastersiana in that shoots of the latter taxon are glabrous from the beginning (Iwatsuki et al. 1995).

Distribution and Ecology

S Japan: Kyushu, restricted to the islands of Yakushima (three populations) and Tanegashima (one population), at elevations of 100 to 800 m, on rocky slopes (Iwatsuki et al. 1995, Kanetani et al. 2004). Hardy to Zone 9 (cold hardiness limit between -6.6°C and -1.1°C) (Bannister and Neuner 2001).

The remaining population on Tanegashima is severely depressed and has very low population density, resulting in a high incidence of self-pollination and reduced production of viable seed. Kanetani et al. (2004) suggest that "The serious decline [of P. amamiana] necessitates ... protection and management ... for in situ populations on both islands, and demise from pine wilt disease should be carefully monitored. The small, diffuse population on Tane-ga-shima Island requires artificial cross pollinations for restoration of seed fertility and successful reproduction. Additionally, the establishment of ex situ plantations containing grafts of mature trees ... is needed to ensure conservation of genetic diversity of Tane-ga-shima Island populations."

Remarkable Specimens

Ethnobotany

Like most white pines, it grows to large sizes and produces a high quality wood that historically made it attractive as a source of fine timber. Also like most white pines, its usefulness led to severe overexploitation. P. amamiana was always endemic to the islands of Yakushima and Tanegashima, and the overexploitation took it to the brink of extinction. The authorities on Tanegashima were diligent record-keepers, and the harvest of large P. amamiana trees was regulated by the local government from the 16th through the 19th century. For example, in 1755, 218 trees with a girth of 210 to 420 cm were harvested. During the late 19th and early 20th centuries, many trees were harvested for making fishing canoes (the wood is quite resinous, making it resistant to decay) and for house construction. For instance, in 1918, 455 canoes were made, probably from P. amamiana. Canoes were used for fishing until twenty years ago on Tanegashima (Kanetani et al. 2001, cited by Kanetani et al. 2004).

Currently, human activity toward the species is concerned with preserving it and its habitat.

Observations

It can be seen in parks in Kagoshima City, Kyushu, and in habitat within Yakushima National Park (30.33°N, 130.50°E), a World Heritage site. The park is also famous for its ancient groves of Cryptomeria japonica, which grow at montane elevations. The area also has Abies firma and Tsuga sieboldii.

Remarks

The epithet amamiana honors the Amami people, who inhabit the Ryukyu Islands.

Many trees have been killed by pine wilt disease, caused by the pathogenic nematode Bursaphelenchus xylophilus. The pathogen poses a significant threat to remaining wild populations of P. amamiana (Nakamura et al. 2001, Akiba and Nakamura 2005), despite the fact that the species is relatively resistant to this pathogen, more so than trees of co-occurring P. thunbergii (Nakamura et al. 2003).

Citations

Akiba, M. and K. Nakamura. 2005. Susceptibility of an endangered tree species Pinus armandii var. amamiana to pine wilt disease in the field. Journal of Forest Research 10:3-7.

Frankis, M. P. 1989. Some interesting, unusual and recently described pines. Conifer Society of Australia Newsletter 5: 12-15.

Kanetani, S., K. Gyokusen, A. Saito, and H. Yoshimaru. 2001. The distribution of an endangered tree species, Pinus armandii Franch. var. amamiana (Koidz.) Hatusima, in Tane-ga-shima Island. Forest Tree Breeding special issue: 34-37 (in Japanese).

Kanetani, S., T. Kawahara, A. Kanazashi, and H. Yoshimaru. 2004. Diversity and conservation of genetic resources of an endangered five-needle pine species, Pinus armandii Franch. var. amamiana (Koidz.) Hatusima. Pp. 188-199 in R.A. Sniezko, S. Samman, S.E. Schlarbaum, and H.B. Kriebel, eds., Breeding and genetic resources of five-needle pines: growth, adaptability and pest resistance. 2001 July 23–27; Medford, OR, USA. IUFRO Working Party 2.02.15. Proceedings RMRS-P-32. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. Available: http://www.fs.fed.us/rm/pubs/rmrs_p032/rmrs_p032_188_191.pdf, accessed 2008.09.06.

Koidzumi, G. 1924. Contributiones ad cogitionem Florae Asiae Orientalis. Botanical Magazine Tokyo 38: 88-113 (p. 113).

Nakamura, K., M. Akiba, and S. Kanetani. 2001. Pine wilt disease as promising causal agent of the mass mortality of Pinus armandii var. amamiana (Koidz.) Hatusima in the field. Ecological Research 16:795-801.

Nakamura, K., M. Akiba and S. Kanetani. 2003. Characteristics of the resistance of Pinus armandii var. amamiana, an endangered pine species in Japan, to pine wilt disease. Pp. 94-95 in Proccedings: IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences.”

Takehara, H. 1976. Pinus armandii var amamiana Hatusima. Forest Genetics Resources Information 5: 28-29.