|Scientific Name:||Ostrya rehderiana|
|Red List Category & Criteria:||Critically Endangered B1ab(i,ii,v)+2ab(i,ii,v); C2a(i,ii); D ver 3.1|
|Assessor(s):||Shaw, K., Roy , S. & Wilson, B.|
This species was listed as Critically Endangered (under criterion D1) in the 1998 World List of Threatened Trees. The same category (Critically Endangered) is given here. New updated information on its population size and range mean that more criteria (B, C and D) have now been able to be used to assess this species. There are only five individuals remaining in the wild. These are found in a very restricted range (extent of occurrence (EOO) and area of occupancy (AOO) both equal to 0.4 km2) representing one location and with continuing decline in the number of mature individuals, EOO and AOO. Continued conservation efforts for this species are essential to ensure its continued survival.
|Range Description:||This species occurs only in the western part of Tianmu Mountain (Mount Xitianmu) in Zhejiang Province, China, with an estimated extent of occurrence (EOO) and area of occupancy (AOO) of 0.4 km2.|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||When first recorded in 1927 this species was fairly common in the woods of Tianmu Shan (Tianmu Mountain) of Zhejiang Province, China. However, there has been a rapid reduction in population size and this species is now considered an extremely rare tree. The wild population of this species is reported to consist of five individual trees (Li et al. 2013). All individuals have been drastically damaged; one of them, which is one metre in chest height diameter, has had the top of its trunk broken, and the other four have had their lower lateral branches cut off. The Flora of China (2008) notes that this species is Endangered and reports only one single known individual tree at a roadside. This assessment uses the more up to date population information from Li et al. (2013). Population decline is projected to continue. Visible damage to remaining individuals highlights continued threats.|
|Habitat and Ecology:||This species is a deciduous tree growing up to 21 m tall, occurring in broad-leaved forests. The mean annual temperature in the region is 15°C (mean January temperature 3.3°C and mean July temperature 28°C). The annual precipitation is 1,471 mm with a peak in June, annual mean relative humidity is 78% and the species occurs in red soil with pH 4.7-5.3. The plants associated with this species are Pinus massoniana, Cyclobalanopsis glauca, Castanopsis sclerophylla, Dalbergia hupeana and Lespedeza davidii. The male inflorescences bud in July and blossom in the following April; the female inflorescences appear while buds are developing and leaves completely unfold in April. The fruits ripen in September and leaves fall in November. This is the only species of the genus Ostrya occurring in eastern China, making it of great interest in the study of systematics of the genus.|
|Use and Trade:||There is no use or trade information available for this species.|
The rapid reduction in the population of this species was most probably due to deforestation and planting of bamboos. The continued habitat destruction and human disturbances are a major threat to this species. Visible damage to remaining individuals shows that human disturbance continues to threaten this species. Continued habitat destruction weakens regenerative ability and results in very few seedlings beneath the remaining individuals. Competition from other species is also a threat to this species, especially bamboo which is a fast growing species reaching full size within three to four months.
This species has been reported to have a very limited natural recruitment as well as a high mortality rate. A recent study found low levels of genetic diversities in the five extant, naturally regenerating individuals. It is unlikely the species has experienced a long-term bottleneck as the previous population was quite common, however there is evidence of inbreeding depression having an effect on offspring survival.
|Conservation Actions:||Conservation of this species, both in situ and ex situ, is essential to ensure its survival. Mount Xitianmu (West Tianmu Mountain) has been declared as a nature reserve and great attention has been given to this species. Stone fences have been erected around the trees by the roadside where individuals are extremely threatened. To stimulate natural regeneration, the public needs to be educated not to destroy and trample the existing stands. Despite efforts, they do not appear to be regenerating well naturally. Although the Hangzhou Botanical Garden and the Zhejiang College of Forestry have the species in cultivation, it is still necessary to collect additional seeds for breeding to expand the cultivation program. The species is also subject to legal protection. It has been recommended that the cutting of bamboos and trees, that compete with this species for light, be considered especially in habitats that contain both mature individuals and seedlings. Ex situ conservation is also essential to ensure survival of this species.|
|Citation:||Shaw, K., Roy , S. & Wilson, B. 2014. Ostrya rehderiana. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 02 August 2015.|
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