Taxus mairei (Lemée & H. Lév.) S.Y.Hu

Taxaceae

Scattered throughout southern China, Taiwan and parts of the eastern Himalayas as well as southern Vietnam. Subpopulations are severely fragmented and threatened due to overexploitation for medicinal use, deforestation for agricultural purposes and urbanisation.

Associated Names:

Description

Taxonomic notes

Traditionally this species has beeen regarded as being endemic to mainland southeastern China with an isolated occurrence near Tengchong in Yunnan, and on the island of Taiwan. This distribution forms the basis for the current IUCN Redlist assessment. However, recent studies of Taxus populations across the Himalayas and southeast Asia have confirmed that this species also occurs in Nepal, northeast India, Myanmar and Vietnam (Poudel et al. 2012). Taxus in these areas are usually identified as T. wallichiana. The research has also raised questions about the identity of the Taiwanese subpopulations (Jie Liu et al. 2011, Zhang et al. 2009).

Distribution

Throughout its range it occurs sporadically, usually in small stands, with the main subpopulations in southeast China. In this area it is concentrated in the higher rainfall areas of the Wuyi and Nanling Mountains (Zhang et al. 2009). An unusually large subpopulation has recently been reported from Ruyuan county in Guangdong (Yang Yong, pers.comm. 2012). In Taiwan it is known from 6-7 localities and considered to be very rare.

In Nepal T. mairei occurs in Kavre and Sindhuli districts while in Bhutan it occurs in Central and Western Bhutan. In India it has been identified from Meghalaya in the Khasia hills and at lower altitudes below 2000 metres above sea-level in Nagaland and Manipur. It has also been identified from the Shan and Chin states in Myanmar at low altitudes. In southern Vietnam it is known from several small subpopulations in Lam Dong and Khanh Hoa provinces. Its disjunction in southern Vietnam may be an artefact of the lack of botanical exploration in areas to the north and northwest, especially in Lao PDR.

Habitat and Ecology

Taxus mairei is generally found at relatively lower altitudes than other members of the genus in Asia. In the Himalayan part of its range it usually occurs between 1200 and 2000 metres above sea-level whereas in eastern China most occurrences are below 1200 metres. In Taiwan it may occur as high as 2700 metres above sea-level. In all parts of its range it favours areas with low winter and high summer rainfall and almost subtropical temperature ranges (Poudel et al. 2010). In the Himalayas it is found in evergreen forests, usually as a small tree in the understorey. In southern China it often occurs along streams in coniferous and mixed conifer-angiosperm forests and their more or less open, scrubby margins. It may also occur in secondary forests or as remnant multistemmed shrubs following forest clearance. In southern Việt Nam T. mairei has been found growing in submontane evergreen mixed forests associated with the conifers Cephalotaxus mannii, Dacrycarpus imbricatus, Keteleeria evelyniana, Nageia wallichiana, and Podocarpus neriifolius.

Human Uses

Taxus mairei has been heavily exploited throughout its range for Taxol production. It is also used in Amchi, Ayurveda, Han Chinese and Unani traditional medicinal systems to treat ailments such as gastro- intestinal disorders, respiratory problems and skeletal system disorders. Locally the arils may be eaten, the wood used for construction, especially tool handles and the foliage for fodder or animal bedding (Poudel et al. 2013).

Conservation Status

Global status and Rationale

Vulnerable A2d

The current Global status of the species is based on an estimated decline in the Chinese subpopulations of more than 30% over the last three decades. The principal driver for the recent decline has been exploitation of its bark and foliage for chemical/medical purposes, compounding a more gradual range wide decline associated with increasing rural populations and an expansion of agriculture.

Under the IUCN's current categories and criteria, the recent identification of other populations in the eastern Himalayas and Vietnam would not alter this assessment. Although T. mairei's geographic range has considerably expanded, the subpopulations in these area are very small and restricted and do not add significantly to the size of the global population.

Proposed National Status and Rationale - Bhutan

Endangered A2cd
As in Nepal, its distribution is limited and in an altitudinal zone that is susceptible to deforestation. However exploitation has been less intensive.

Proposed National Status and Rationale - China

Vulnerable A2cd
The main part of the population occurs in southern China, especially in the southeast. A declineof more than 30% is estimated to have occurred within the last 25 years following exploitation for Taxol production. Its distribution also coincides with areas of China that have undergone rapid economic development during the same period. Many localities have disappeared and the remaining subpopulations are highly fragmented and restricted to a few protected areas or more remote localities.

Proposed National Status and Rationale - India

Critically Endangered A2cd
In northeast India all Taxus populations (as T. wallichiana) have been heavily exploited and have been regionally assessed as Endangered. As the T. mairei stands represent a small proportion of the Taxus in this area it is likely that they are even more endangered.

Proposed National Status and Rationale - Myanmar

Data Deficient DD
Records from Myanmar are based on historic herbarium specimens and the full extent of its distribution is uncertain. However it is likely to have been exploited for traditional medicine and has probably had its range and population size reduced due to general deforestation and conversion of its habitat for agriculture.

Proposed National Status and Rationale - Nepal

Critically Endangered A2cd, B2ab(iii,iv,v)
In Nepal stands consist of very few trees in a few localities at relatively low altitudes. They have been impacted by expanding agriculture in addition to being over exploited for modern and traditional medicines.

Proposed National Status and Rationale - Taiwan

Endangered A2cd; B1ab(iii,v)
The Taiwanese subpopulation has undergone a recent decline due to harvesting for Taxol production and for timber. Conversion of forests for agriculture has also led to a decline in area of occupancy.

Proposed National Status and Rationale - Vietnam

Endangered B2ab(iii), C1
In southern Vietnam the total subpopulation is estimated to be less than 500 mature trees distributed in several localities. Some localities consist of isolated fragments of the original forest located along ridges or streams within predominantly agricultural landscapes. These are very susceptible to fires. A estimated decline of 20% within the next two generations is likely.

Conservation Actions

Taxus mairei, like most other Asian Taxus species is listed on Apendix II of CITES so that its international trade is regulated. In China this species has First Class Protected Status which provide national legal protection. In addition it occurs in a number of protected areas such as Nanling National Nature Reserve in Guangdong, Dupangling National Nature Reserve in Hunan and Wuyanling Mountain National Nature Reserve in Fujian. Considerable efforts have been made to establish plantations for future harvesting.

In Nepal government forestry regulations regulate the harvesting and prohibit the felling of all Taxus species. As in China plantations are being established and programmes are being developed to encourage its protection and cultivation in community forests as well as on private land. Similar measures are in place in Bhutan. In Vietnam most stands are within protected areas and regular inventories are carried out to ensure that trees are not exploited.