Upper treeline ecotone at 4,850 m with multi-stemmed trees of J. tibetica on the southern Yamco Yumco peninsula (28.900° N, 90.567° E), southern exposure [G. Miehe, 1998.08]. Source, Miehe et al. (2007a).
Chorten in Qamdo Prefecture, Tibet. Trees in background include J. tibetica (probably) and Picea likiangensis [Daniel Winkler, 1997.07].
Juniperus tibetica
Tibetan juniper, 大果圆柏 daguo yuanbai [Chinese; literally, "high mountain juniper"].
Juniperus tibetica is a member of the turbinate-seed-cone clade of central Asia, which contains about 20 taxa, most of which are high-elevation shrubs of very similar appearance. It shares, with J. morrisonicola and J. squamata, a sub-clade sister to all the other turbinate-seed-cone taxa (Adams and Schwarzbach 2013). Both J. tibetica and J. morrisonicola might reasonably be treated as infraspecific taxa of J. squamata; J. morrisonicola has been so described, but J. tibetica has not.
Synonymy (Adams 2008):
Type: Tibet, Jinsha River, in forest near temple, V. F. Ladygin 25 (holotype SBT, isotype PE).
Gene-flow work comparing J. tibetica with three closely-related other junipers of the Qinghai-Tibetan Plateau, J. convallium, J. saltuaria and J. przewalskii, has given us a glimpse of the complex evolutionary history of the turbinate-cone juniper clade, finding evidence of "both incomplete lineage sorting and gene flow after species divergence" (Li et al. 2011; see this source for considerable further insights regarding this group).
Dioecious or monoecious shrubs or trees to 30 m tall. Bark brown, exfoliating in longitudinal strips. Twigs mostly straight, round to 4-angled, 1-2 mm diameter. Leaves both whip-like and scale-like. Whip leaves in whorls of 3, 4-8 mm long, only found on young plants. Scale leaves in whorls of 3 or 4, ovate-rhombic, obtuse, 1-3 mm long, with a central, conspicuous, slightly depressed, linear-elliptic gland. Seed cones erect, maturing brown-black in 2 years, turbinate, 9-16 × 7-13 mm, each bearing 1 ovoid seed, 7-11 × 6-8 mm, bearing deep resin pits. Pollen shed in March to April (Adams 2008). See García Esteban et al. (2004) for a detailed characterization of the wood anatomy.
China: S Gansu, SE Qinghai, Sichuan, S and E Xizang (Tibet). Climate continental; grows at elevations of 2600 to 4900 m on rocky and gravelly (both siliceous and calcareous) soils, on mountain slopes or in valleys. Often grows with J. convallium in yak-grazed woodlands with Cyperaceae mats, Berberis scrub, or Artemisia steppe. At relatively low elevations it also occurs in south-facing clearings in Picea forests, and at the highest elevations it is also restricted to south aspects. Locally, occurs in groves of Cupressus gigantea (Adams 2008, Farjon 2005, Farjon 2013).
This species accounts for the highest trees growing in the northern hemisphere, with erect arboreal growth forms observed at elevations of up to 4900 m, in southeast Tibet, where they occur on southern exposures with rocky substrates (Miehe et al. 2007b). The species is hardy to Zone 6 (cold hardiness limit between -23.2°C and -17.8°C) (Bannister and Neuner 2001). (The highest trees in the world, sadly, are not gymnosperms; they are Polylepis sp. growing in Bolivia [Purcell et al. 2004].)
J. tibetica is classed "vulnerable" due to increasing development pressure that leads to habitat loss and exploitation of the trees, chiefly for firewood; regrowth is very slow. Yak grazing likely limits regeneration. The population is severely fragmented, with an estimated area of occupancy of only 1,175 km2 within an extent of occurrence of 1,044,420 km2, and the population trend is declining (Farjon 2013).
He et al. (2018) present a tree-ring chronology covering the period 1067 to 2010. They don't say if their sampling methodology only sampled living trees, but it seems likely, in which case they found at least one tree that was at least 943 years old. The chronology was used a study of long-term early summer drought severity covering 821 years.
This is the principal high altitude tree within most of its range, and consequently is the principal source of forest products to native people within that area. It is exploited mainly for firewood, and is also used for incense in Buddhist rituals (there are many Internet sources of such incense, but I have doubts about how much of it is J. tibetica; many other junipers also provide Buddhist incense). It is rarely seen in plantings outside of Tibet (Farjon 2013).
The epithet refers to the species' native range, Tibet.
Adams, Robert P. 2008. Junipers of the World, 2nd ed. Vancouver: Trafford Publ. Co. vi+402 pp.
Adams, R. P., and A. E. Schwarzbach. 2013. Phylogeny of Juniperus using nrDNA and four cpDNRA regions. Phytologia 95:179-187.
Farjon, A. 2013. Juniperus tibetica. The IUCN Red List of Threatened Species 2013. https://www.iucnredlist.org/details/42256/0, accessed 2018.02.09.
He Minhui, Achim Bräuning, Jussi Grießinger, Philipp Hochreuther, and Jakob Wernicke. 2018. May–June drought reconstruction over the past 821 years on the south-central Tibetan Plateau derived from tree-ring width series. Dendrochronologia 47:48-57.
Komarov. 1924. Bot. Mater. Gerb. Glavn. Bot. Sada RSFSR 5:27.
Li Zhonghu, Jiabin Zou, Kangshan Mao, Kao Lin, Haipeng Li, Jianquan Liu, Thomas Kallman, and Martin Lascoux. 2011. Population genetic evidence for complex evolutionary histories of four high altitude juniper species in the Qinghai–Tibetan Plateau. Evolution 66(3):831-845, doi:10.1111/j.1558-5646.2011.01466.x.
Miehe, G., S. Miehe, M. Will, L. Opgenoorth, L. Duo, T. Dorgeh, and J. Liu. 2007a. An inventory of forest relicts in the pastures of Southern Tibet (Xizang A.R., China). Plant Ecology 194(2):157–177.
Miehe, G., S. Miehe, J. Vogel, S. Co, and L. Duo. 2007b. Highest treeline in the northern hemisphere found in southern Tibet. Mountain Research and Development 27(2):169-173.
Purcell, J., A. Brelsford, and M. Kessler. 2004. The world’s highest forest. American Scientist 92:454–461.
Farjon (2005) provides a detailed account, with illustrations.
The species account at Threatened Conifers of the World.
Last Modified 2024-11-27
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