Common name: Bach vang
English name: golden cypress
Scientific name: Xanthocyparis vietnamensis Farjon & Hiep
CRITICALLY ENDANGERED B2ab (v)
[CRITICALLY ENDANGERED B1ab(ii-v), 2ab(ii-v)]
Existing national status NOT EVALUATED
Proposed national assessment CRITICALLY ENDANGERED B1ab(ii-v), 2ab(ii-v) This species is listed as Critically Endangered due to its restricted occurrence, limited habitat, and the effects of selective logging and forest fire. The most recent survey recorded a total of 561 trees scattered over three communes, only 290 of which were mature trees (To Van Thao et al., 2004).
Tree with pyramidal habit when young, broad, flattened crown when mature, reaching up to 15 m high with a dbh to 0.8 m. One of the striking morphological features of Xanthocyparis vietnamensis is the occurrence of two distinct types of leaves on many mature trees. It has both branches with juvenile leaves and those with mature, scale-like leaves.Only the latter type bears either male or female cones. It is found in the second layer of the primary closed evergreen tropical seasonal coniferous Pseudotsuga sinensis submontane forests on top ridge of highly eroded solid crystalline white limestone mountains (mean annual temperature 14-180C, annual rainfall 2000 - 2400 mm). Found scattered associated with Nageia fleuryi, Podocarpus pilgeri, Calocedrus rupestris, Taxus chinensis and Amentotaxus sp. Natural regeneration is rare; saplings contribute about 10-15% of total number of trees (To Van Thao et al., 2004).
Xanthocyparis vietnamensis Farjon & Hiep
A. Branchlet with scale leaves and seed cones. B. Branchlet with scale leaves and needle leaves. C. Branchlet with scale leaves. D. Branchlet with needle leaves. E. Detail of upper and lower side of needle leaf. F. Branchlet with pollen cone. G. Microsporophyll with two microsporangia. H, I. Seed cones, closed and open. J. Seeds. [A, C, F-J from Harder et al. 6091; B, D, E from Harder et al. 6224. (Illustration by Aljos Farjon).
Very narrow local endemic to Bat Dai Son limestone massif, Quan Ba District in Ha Giang Province.
Locally valued for its fragrant, durable timber.
The already small population is primarily threatened by forest fragmentation and by selective logging (Farjon et al., 2004a). Regeneration is variable; recent seed collections from specific localities and subsequent germination trails have not been successful (Nguyen Duc To Luu, 2004; unpublished data).
Protected Area status
All of the population lies within the Provincial Protected Area of Bat Dai Son. Local logging remains a problem.
Current conservation measures
Vegetative propagation trials have been successfully undertaken by the Central Forest Seed Company with 30 clones. Seed trials are ongoing (To Van Thao et al., 2004; Nguyen Duc To Luu, 2004, unpublished data) and replanting programmes are also being undertaken by Institute of Ecology and Biological Resources in the Bat Dai Son Provincial Protected Area.
Recommended conservation action
This species should be fully protected by law by inclusion in Group IA of the List of Rare and Precious Flora and Fauna and Vietnam Red Data Book. Awareness-raising, especially in Thanh Van Commune where most of the illegal logging occurs (To Van Thao et al., 2004), is important for effective conservation. Seed study and propagation work should be promoted to providing planting material for restoration. On-site replanting is necessary to increase population size to ensure increased regeneration in the future.
Surce: Nguyen Tien Hiep, Phan Ke Loc, Nguyen Duc To Luu, Philip Ian Thomas, Aljos Farjon, Leonid Averyanov and Jacinto Regalado Jr. "Vietnam Conifers, Conservation satus review 2004"