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Tom Christian (2021)
Christian, T. (2021), 'Abies yuanbaoshanensis' from the website Trees and Shrubs Online (treesandshrubsonline.
Tree to 25 m tall, <1 m dbh. Bark reddish-brown and smooth in young trees, becoming ridged, grooved, fissured and breaking into stiff plates with age. First order branches long, horizontally spreading; second order branches horizontal or assurgent. Branchlets horizontal or assurgent, slender, stiff, yellow- or buff-brown at first, becoming pale-brown then dark-brown, glabrous. Vegetative buds ovoid-conical, very resinous. Leaves densley set on the shoots in several overlapping ranks, those above shortest, 1–3(–3.8) cm × 1.8–2.5 mm, (juvenile plants with longer leaves usually of equal length all around shoot), base twisted, margins flat, apex obtuse or emarginate, dark green with a central groove above, two bright white stomatal bands beneath. Pollen cones axillary, usually solitary, oblong-cylindrical, 1–1.5 cm long, yellow. Seed cones subsessile, broadly ovoid-cylindric, apex obtuse, 8–9 × 4.5–5 cm, green or yellow-green when immature, pale yellowish-brown and finally brown when ripe; seed scales cuneate-flabellate, 2 × 2.2 cm at midcone; bracts large, strongly exserted, outspreading, and stiff at maturity, the same colour as the seed scales. (Farjon 2017; Debreczy & Rácz 2011; Fu, Lü & Mo 1980).
Distribution China N Guangxi (Rongshui Xian, Yuanbao Shan)
Habitat Cool-temperate mountain forests at 1700–2050 m asl, with high humidity and abundant precipitation including much snow. The most common woody associates include the conifer Tsuga chinensis and members of the Fagaceae including Fagus engleriana. Cephalotaxus latifolia, Podocarpus wangii, and Taxus chinensis are scattered in the forest; the understorey includes a strong sub-tropical element.
USDA Hardiness Zone 6-8
RHS Hardiness Rating H6
Conservation status Critically endangered (CR)
The entire wild population of Abies yuanbaoshanensis numbers only about 700 trees, which are all restricted to an area of less than 20 ha in north-central Guangxi Province (globaltrees.org). Its occurrence here on the eponymous mountain is due to a previous expansion of Abies in Asia when the climate was cooler than it is today. Nowadays, as with other relict firs endemic to single mountains in cental and southern China, it appears something of an anomaly, and this has fuelled speculation as to its true alliegances within the genus. Farjon (2017) considers it a close relative of A. forrestii and therefore places it in Section Pseudopicea, along with the other ‘blue coned’ firs of the Sino-Himalayan area. Although it has several characters in common with these firs, it differs from them in several ways, too, most obviously in the cones which are green or yellow-green when they are immature, ripening through yellows to brown, but never blue. Together with details of its ecology, this suggests a closer affinity with Section Momi which includes species such as A. firma in Japan and A. ziyuanensis in China (another narrow endemic). These and related firs are certainly better adapted than those of Section Pseudopicea to compete with mixed broadleaf forest at lower elevations, and they are also widely acknowledged as being more heat tolerant.
Along with A. ziyuanensis, Yuanbaoshan Fir was described to science in 1980 (Fu, Lü & Mo 1980). Being relict species distributed well away from the usual haunts of western collecting teams, in very difficult-to-access habitats, they have both remained extremely rare in cultivation, represented by only a handful of individuals in each case. Shaw & Herd (2014) note that A. yuanbaoshanensis was only reported from a single collection in BGCI’s global survey of ex situ conifer collections, but it was slightly more widespread than this even then. Given that both are categorised as Critially Endangered and that decline is ongoing in both cases, there is a growing imperative to ensure that an effective ex-situ conservation population is established in an international network of botanic gardens.