Lidar point cloud model of the tallest tree in China (Xing 2023.04.01) (11 MB animated file, may load slowly).
Lidar point cloud model of the tallest tree in China (Xing 2023.04.01) (11 MB animated file, may load slowly).
Cupressus austrotibetica
Tibetan cypress, Yunnan cypress, 西藏高柏 [Chinese, lit. "Tibetan tall cypress"], 喜马拉雅柏 [Chinese, lit. "Himalayan cypress"].
Type: F. Ludlow, G. Sherriff, & H. H. Elliot 12141, Tibet, Trulung, Pome, 7000 ft (2130 m), 1947.01.13. "These magnificent trees appear first near the junction of the Po Tsangpo and Yigrong Chu. They become more numerous further up the river, in mixed forest." [Image and data]. This is a member of a Cupressus clade that evidently speciated during the rise of the Himalayas about 10-13 million years ago to produce the modern taxa C. cashmeriana, C. duclouxiana, C. gigantea, and C. torulosa (Little 2006, Xu et al. 2010, Terry et al. 2018). Although described in 1988, this taxon was not widely recognized and was reduced to synonymy by various authorities to as late as 2010 (Farjon 2010). This is a bit surprising as it is a large tree with very distinctive foliage; regardless, molecular studies using a variety of markers have now established it as a valid species (Rushforth et al. 2003, Little 2006, Xu et al. 2010, Terry et al. 2018, Maerki and Hoch 2021).
Synonymy:
Evergreen monoecious trees to 102 m tall, typically developing a narrow columnar habit. Twigs very thin, thread-like, somewhat flattened. Leaves bluntly acute, 1.2-1.5 mm long; glands obscure, with a small pit. Seed cones globose or subglobose, dark brown, 12-16 mm long with 10-12 scales, inner scales dark brown, umbos inconspicuous. Seeds dark brown, subglobose, with rounded wings, ending in an acuminate point at the end (Silba 1988). Rushforth et al. (2003) say the seed cones have 8 scales with a maximum diameter of 12 mm.
"C. austrotibetica is one of the rare cypresses which can be identified at first glance by its foliage. The branchlets are very thin and often elongated giving the impression of airy foliage" (Maerki and Hoch 2021). C. duclouxiana has relatively more prominent leaf glands with a deep pit, has larger seed cones with deep reddish inner scales (Silba 1988), and lacks a central point on the seed cone scale. C. rushforthii has more closely adpressed leaves, and the twigs are thicker and less elongated (Maerki and Hoch 2021). C. torulosa has larger seed cones and thicker twigs (ultimate branches >1 mm diameter, vs. <1 mm in C. austrotibetica) (Rushforth et al. 2003).
Tibet (= China: Xizang), associated with the gorges of major rivers in the area bounded by latitude 29.9° to 30.3° and longitude 94.7° to 95.1°. Elevations are 1980-2800 m, possibly much higher, but collections to date have been near roads alongside of rivers. Climate is cool temperate, with annual precipitation of 2300 m, with 80% falling from March through September (Silba 1988, Maerki and Hoch 2021, Rushforth et al. 2003). Species associations have not been recorded, but Rushforth et al. (2003) report collection from young trees on a rocky bank above the road at circa 2100 m beside the Yigrong Tsangpo, where trees 40–60 m tall could be seen on forested ridges above. They also report collections from maturing trees 15 m tall growing beside a steep cliff at the edge of the Po Tsangpo, at about 2200 m elevation.
The IUCN has not assessed the conservation status of this species. Maerki and Hoch (2021) report that "no major threats seem to endanger these populations" although these gorges are under consideration for dam construction. However, the species has only been collected a few times in over a century, and seems to have a very limited range and a very limited area of occupancy, factors that might qualify it as "Endangered" under the IUCN assessment protocol. However, it is significant that the tallest tree in China belongs to this species, which makes it a symbol of national pride and by inference a high priority for protection; it can thus be called conservation-dependent. At this time (2024), no conservation reserves have yet been designated, but the tallest tree was only found last year.
The tallest tree in the world outside of California (where Sequoia gets to over 115 m) is a cypress in the Yarlung Tsangpo gorge of Tibet, reported by Chinese scientists in May 2023 (Xing 2023, Global Times 2023). Following initial explorations dating as early as 2013, the tree was found on 2023.05.20 using lidar surveys performed by a drone, with further surveys performed to study the tree in detail. Measurements showed it to be 102.3 m tall and 293 cm dbh. The surveyors found another 25 trees over 90 m tall, as well. The species was reported as "Tibetan cypress" and other accounts variously named it as Cupressus torulosa or C. rushforthii, but Ren et al. (2024) confirm its identity as C. austrotibetica.
This large and attractive tree was often planted near temples (Xu et al. 2010).
Some specific locations for field collections are listed by Maerki and Hoch (2021), and they also cite ornamental specimens at several U.K. arboreta.
The epithet means "southern Tibet". The species was first collected by a British survey party in early July 1913, and that specimen is now a paratype. A detailed account of the tree's discovery is given by Maerki and Hoch (2021, p. 86).
Global Times. 2023.05.28. Asia’s tallest tree at 102.3 meters found in SW China’s Xizang. https://www.globaltimes.cn/page/202305/1291477.shtml, accessed 2023.05.29.
Little, Damon P. 2006. Evolution and circumscription of the true cypresses (Cupressaceae: Cupressus). Systematic Botany 31(3):461–80.
Maerki, Didier, and Jean Hoch. 2021. Cupressus rushforthii, a new cypress species in Xizang, China. Bulletin of the Cupressus Conservation Project 10(2):55–89.
Ren, Yu, Hongcan Guan, Haitao Yang, Yanjun Su, Shengli Tao, Kai Cheng, Wenkai Li, et al. 2024. Discovering and measuring giant trees through the integration of multi‐platform lidar data. Methods in Ecology and Evolution 2041-210X.14401. https://doi.org/10.1111/2041-210X.14401.
Rushforth, Keith D., Robert P. Adams, M. Zhong, X.-qiang Ma, Ram Naresh Pandey, et al. 2003. Variation among Cupressus species from the eastern hemisphere based on random amplified polymorphic DNAs (RAPDs). Biochemical Systematics and Ecology 31(1):17–24.
Silba, John. 1988. A new species of Cupressus L. from Tibet. Phytologia 65(5):334. Available: Biodiversity Heritage Library, accessed 2024.12.08.
Terry, Randall G., Andrea E. Schwarzbach, and Jim A. Bartel. 2018. A molecular phylogeny of the Old World cypresses (Cupressus: Cupressaceae): evidence from nuclear and chloroplast DNA sequences. Plant Systematics and Evolution 304(10):1181-1197.
Xing, Fangyu. 2023.05.27. 102.3 meters! The tallest tree in Asia found in Xizang, China. CGTN. https://news.cgtn.com/news/2023-05-27/102-3-meters-The-tallest-tree-in-Asia-found-in-Xizang-China--1k95F5TYksU/index.html, accessed 2024.12.08.
Xu, Tingting, Richard J. Abbott, Richard I. Milne, Kangshan Mao, Fang K. Du, Guili Wu, Zhaxi Ciren, Georg Miehe, and Jianquan Liu. 2010. Phylogeography and allopatric divergence of cypress species (Cupressus L.) in the Qinghai-Tibetan Plateau and adjacent regions. BMC Evolutionary Biology 10(1):194. https://doi.org/10.1186/1471-2148-10-194.
Photographs and maps in Maerki and Hoch (2021).
Yang, Heng, Jialiang Li, Richard Ian Milne, Wenjing Tao, Yi Wang, Jibin Miao, Wentao Wang, et al. 2022. Genomic insights into the genotype–environment mismatch and conservation units of a Qinghai–Tibet Plateau endemic cypress under climate change. Evolutionary Applications 15(6):919–33. https://doi.org/10.1111/eva.13377. Although this work nominally examines C. gigantea, it's apparent that they also sampled one population of C. austrotibetica, and a second population shows some evidence of introgression between the two species.
Last Modified 2024-12-10
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