Pinus kesiya (Thông ba lá, 思茅松) description

Pinus kesiya

Royle ex Gordon (1840)

Common names

Thông ba lá [Vietnamese]; 思茅松 ka xi song [Chinese]; Pin à trois feuilles, pin d’Indochine [French]; tinyu [Burmese]; tapulao [Filipino]; saral,far,dingse,dingsa,dieng-kysi [Hindi]; mai hing [Lao]; chuang [Thai]; Benguet pine, Khasya pine, Khasi pine [English].

Taxonomic notes

There are two varieties, Pinus kesiya var. kesiya and Pinus kesiya var. langbianensis (A.Chev.) Gaussen ex Bui (1962). Both have a number of synonyms, listed by POWO, but the only one in widespread use is Pinus insularis in lieu of P. kesiya var. langbianensis; this usage is mostly seen in the Philippines.

Molecular analyses using both nuclear and plastid markers have consistently placed this species sister to P. yunnanensis (or to a P. densata+P. yunnanensis clade, where P. densata is thought to have originated as a P. kesiya × yunnanensis hybrid). All 3 species share a clade with other E Asian members of subsection Pinus including P. hwangshanensis, P. tabuliformis, and P. thunbergii (Wang et al. 1999, Geada López et al. 2002, Gernandt et al. 2005). P. kesiya and P. yunnanensis currently have adjunct distributions, suggesting these taxa may have diverged only recently and through a vicariant process. A broad zone of introgression occurs where P. yunnanensis and P. kesiya distributions overlap in southern Yunnan. The introgression is asymmetrical, with P. kesiya as the pollen donor. The observed population structure suggests a post‐glaciation range expansion in P. yunnanensis, with P. kesiya range expanding during glacial and contracting during interglacial episodes (Gao et al. 2023).

Description

Tree 30-35 m tall with straight, cylindrical bole. Bark thick, dark brown, with deep longitudinal fissures. Branches robust, red brown from the second year, branches pointing downwards. Leaves dark green, soft, at tip of a short twig, usually 3 per fascicle, 15-20 cm long, fascicle 1.2 cm long and persistent. Cones ovoid, 5-9 cm long, often curved downwards, sometimes slightly distorted; scales of second-year cones dense, umbo a little convex, sometimes acutely spinous. Two relief-lines (transverse and longitudinal) across the middle of the scale surface. Seed winged, 1.5-2.5 cm long. Flowers in April-May; fruits 2 years after (FIPI 1996). In plantations, trees start bearing cones at 5-7 years and bear cone crops annually thereafter (Nyemb n.d.)

The varieties are distinguished by their foliage: var. kesiya has long, drooping leaves, 12-25 cm × 0.5-0.7 mm; var. langbianensis has shorter, more erect leaves 12-18 cm × 0.7-1 mm (Farjon 2010).

Distribution and Ecology

Cambodia; China: Xizang, Yunnan; India: Assam, Meghalaya; Laos; Myanmar; Philippines; Thailand; Vietnam: Lai Chau, Lang Son, Cao Bang, and Quang Ninh. The type variety is more western (India, Xizang, Yunnan, Cambodia, Myanmar, Laos, Thailand), while var. langbianensis is more eastern (Yunnan, Laos, Thailand, Vietnam, Philippines). P. kesiya is also planted as a plantation species in countries including Australia, Ethiopia, Madagascar, Malawi, Malaysia, Papua New Guinea, South Africa, Zambia, Zimbabwe, and parts of South America; and in some of these areas it has escaped the plantations and become naturalized.

Climate associations vary through the species' range. In India, Myanmar, and Thailand it occurs on dry sites at relatively low elevations of 800-1500(-2000) m. Farther east, particularly in Vietnam and the Philippines, at grows on wetter sites (but still with pronounced wet and dry seasons) at highly variable elevations (300-2700 m) in areas with annual precipitation of 700-1800 mm and mean annual temperatures of 17-22°C. Soils are typically acidic, well-drained, siliceous, and low in nutrients or organic matter. In habitat, this shade-intolerant tree usually grows in pure stands or mixed with broad-leaved trees. Natural regeneration is best on mineral soils (Farjon 2010, FIPI 1996, Orwa et al. 2009). Regeneration usually happens in the aftermath of a stand-destroying disturbance, commonly fire, and P. kesiya woodland or savannah are common habitat types (Orwa et al. 2009). Hardy to Zone 9 (cold hardiness limit between -6.6°C and -1.1°C) (Bannister and Neuner 2001).

In the Philippines, P. kesiya is the dominant species of the Luzon Tropical Pine Forests. This very wet area (over 2,500 mm rain per year) nonetheless has a November-April dry season during which fire is common, maintaining pine dominance in the forest. Red crossbill (Loxia curvirostra), a seed-eating songbird known primarily from high-latitude coniferous forests, reaches its southernmost extent in the Old World in these forests, where it subsists largely on the seeds of Pinus kesiya.

Remarkable Specimens

The oldest known living specimen, 285 years, was documented in a tree-ring chronology covering the period 1721-2005 (crossdated after 1748), collected in the northern Philippines by William E. Wright and Nestor Baguinon (doi.org/10.25921/d7zk-7x21). This site was used in a long-term reconstruction of monsoonal precipitation (Cook et al. 2010). Trees in Madagascar have been reported up to 46 m tall at age 38 years (Nyemb n.d.).

Ethnobotany

Within its native range, and elsewhere where plantations have been established, Pinus kesiya is a very important timber species. This is especially true in southern Africa, for instance in Zambia, where it is the most common pine. Under its trade name, khasi pine, it is used for diverse timber needs including fuel, construction, boxes, flooring, ceilings, panelling, joinery, furniture, poles, mine props, boat building, agricultural implements, turnery, and railway ties. It is also used in diverse wood products that include plywood, particle board, and pulpwood. Resin tapped from the trees is distilled to give turpentine and rosin. In some areas, Pinus kesiya is planted as an ornamental (Nyemb n.d.); in the Philippines, it is a popular Christmas tree. Also in the Philippines, coffee plantations are often established beneath an existing P. kesiya overstory (Farjon 2010).

In the Philippines, the resin provided an important commercial source of turpentine during the Spanish colonial period (Heaney and Regalado 1998).

Observations

No data as of 2023.11.03.

Remarks

The epithet refers to the Khasi Hills of India, where J. F. Royle first encountered this pine.

Citations

Bui, N.-S. 1962. Adansonia ser. 2, 2:338. Available: Biodiversity Heritage Library, accessed 2024.01.23.

Cook, E. R., K. J. Anchukaitis, B. M. Buckley, R. D. D'Arrigo, G. C. Jacoby, and W. E. Wright. 2010. Asian monsoon failure and megadrought during the last millennium. Science 328:486-489. DOI: 10.1126/science.1185188

Gao, J., Tomlinson, K.W., Zhao, W., Wang, B., Lapuz, R.S., Liu, J.X., Pasion, B.O., Hai, B.T., Chanthayod, S., Chen, J. and Wang, X.R. 2023. Phylogeography and introgression between Pinus kesiya and Pinus yunnanensis in Southeast Asia. Journal of Systematics and Evolution 62(1), DOI:10.1111/jse.12949

Gernandt, David S., G. Geada López, S. O. Garcia and Aaron Liston. 2005. Phylogeny and classification of Pinus. Taxon 54(1):29-42.

Gordon. 1840. Report on the new species and varieties of hardy trees and shrubs raised in the Horticultural Society's gardens. The Gardener's magazine and register of rural & domestic improvement, January, p.8. Available: Biodiversity Heritage Library, accessed 2011.05.20.

Heaney, L.R., and J.C. Regalado, Jr. 1998. Vanishing Treasures of the Philippine Rain Forest. Chicago: The Field Museum.

Nyemb, Nyunaï. n.d. Pinus Kesiya Royle Ex Gordon. Protabase record display, accessed 2019.02.28.

Orwa, C., A. Mutua, R. Kindt, R. Jamnadass, and A. Simons. 2009. Agroforestree Database:a tree reference and selection guide version 4.0 https://apps.worldagroforestry.org/treedb2/AFTPDFS/Pinus_kesiya.PDF, accessed 2024.01.23.