| Citation |
Harvey-Brown, Y. 2018. Aquilaria crassna. The IUCN Red List of Threatened Species 2018: e.T32814A2824513. https://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T32814A2824513.en. Downloaded on 10 March 2021. |
Description |
DESCRIPTION
In Viet Nam, Aquilaria crassna is described as being found only in scattered stands with low numbers of trees (Loc and Luu 2002). Furthermore Tran et al. (2003) state that the population of A. crassna in Vietnamese forests is decreasing. In Viet Nam it is difficult to find trees with a dbh of over 15 cm (N.H. Nghia pers. comm. 2017).
In Thailand, A. crassna only remains in protected areas, with its densest population being in Khao Yai National Park (Zhang et al. 2008, Rose 2013). In a monitoring plot in Khao Yai National Park the number of A. crassna trees decreased from 238 (2000-2001) to 147 (2008) (Zhang et al. 2008). The species has a scattered and clumped distribution in Lao PDR, with most wild stands have either been logged or are under severe threat (Thomas et al. 2006, Jensen and Meilby 2012).
In Cambodia, A. crassna is described as being very rare and only remaining in small quantities in naturals forest, particularly in protected areas (Rose 2013).
Aquilaria crassna has been heavily exploited in Viet Nam (Loc and Luu 2002), which resulted in population declines of over 80% in the 1990s (Nghia 1998). It is believed that similar losses have occurred across the rest of its range (Nghia 1998). Based on the status on this species across its range and the decline estimate given in Nghia (1998) it is estimated here that over the last three generations A. crassna population decline has been over 80%.
HABITAT AND ECOLOGY
Aquilaria crassna is a light demanding large evergreen tree which is found scattered in natural forest on rocky, shallow ferralitic soil. It commonly occurs along streams (Schmidt and Nguyen 2004). Aquilaria spp. have been observed to have a low natural regeneration and to be slow growing (CITES 2015).
THREATS
The species is threatened by heavily exploitation for agarwood. In Thailand A. crassna is heavily poached in its remaining range (Zhang et al. 2008).
USE AND TRADE
Aquilaria crassna is the major source plant for agarwood, the valuable resin produced by some Aquilaria species, in Viet Nam (Tran el al. 2003). In Viet Nam the wood of A. crassna is used in traditional medicine to assist digestion and as a tranquilliser. It is also prescribed in Vietnamese medicine as a powder, aqueous preparation or tincture to treat gastralgia, nausea, vomiting and anxiety (Lemmens and Bunyapraphatsara 2003). Aquilaria crassna is the preferred species for agarwood used for meditation purposes in Japan, due its particular sweetness when burnt (Lee et al. 2016). Lao PDR is the only country in which A. crassna resides where harvesting of wild trees is still legal (Jensen and Meilby 2012).
This species is frequently grown within home gardens and it is cultivated in large scale industrial plantations in Viet Nam, particularly in Phu Quoc Island and Khanh Hoa Province (Tran et al. 2003, Schmidt and Nguyen 2004). More than 10,000 hectares of A. crassna plantations have been established in Viet Nam (N.H. Nghia pers. comm. 2017). This species has also been cultivated widely across Sumatra in Indonesia (Turjaman et al. 2016). It is estimated that over 5,000 hectares of A. crassna plantations have been established in Lao PDR with 2,000 hectares being planted in 2003 alone (Jenson 2004). In a national review if Aquilaria plantations in China between 2006 and 2010, 40 hectares was found to be A. crassna (Yin et al. 2016).
Commercialisation of agarwood in Lao PDR began between 1975 to 1976 and by the 1980s this has spread across the entire country (Jenson and Meilby 2008). Studies conducted in Lao PDR reveal differences between the quality and quantity of A. crassna in local and national markets, products sold in local markets tend to be sold in larger quantities but are of lower quality whereas at national and regional scales the quality of A. crassna improves and the quantity provided is reduced (Jenson and Meilby 2008). Local people in the Ha Tinh province of Viet Nam have been collecting seedlings of A. crassna from natural forests since 1986 and planting them in their home gardens (Loc and Luu 2002). Loc and Luu (2002) also state that a good income can be made in Viet Nam from selling A. crassna trees for agarwood production.
Analysis of CITES Trade Data between 1996 and 2015, investigating direct trade using importer-reported figures (see Figures 1, 2 and 3 in the Supplementary Material), report Powder as the most commonly exported commodity type (141,149 kg), followed by chips (93,079 kg) (see Figure 1). Between 1996 and 2015 a total of 6,660 live specimens were exported, the key exporters were: Malaysia (2,500) all from wild sources, Lao PDR (2,000) all from artificially propagated sources and Thailand (2,010) all from artificially propagated sources (see Figure 2). Only two countries exported powder during this period: Thailand (137,421.8 kg) and Viet Nam (3,727 kg), of these exports 97,420 kg were from artificially propagated sources and 10,002 kg were from wild sources (TRAFFIC pers. comm. 2017). Analysis of exporter-reported figures for this species shows significantly larger volumes of trade with 4,033,480 live specimens exported. Thailand (2,904,412 specimens) was the largest exporter of live specimens followed by Viet Nam (1,128,968 specimens) (see Figure 3). All exports are reported to be from artificially propagated sources. Although all Aquilaria spp. are listed on appendix II of CITES there are no species identification procedures in place. This makes effective regulation and monitoring of the genus in trade extremely difficult (Soeharto et al. 2016).
CONSERVATION ACTIONS
Aquilaria crassna is cultivated at the Forest Research Institute of Malaysia (FRIM) as apart of an ex situ conservation program (Lee and Mohamed 2016). It is recorded in six ex situ collections on Botanic Gardens Conservation International PlantSearch database (BGCI PlantSearch 2017). All species of the genus Aquilaria have been listed on Appendix II of CITES since 2005. The Viet Nam Red Data Book identified A. crassna as an Endangered species in need of protection and conservation (Loc and Luu 2002). Aquilaria crassna has been assessed as Critically Endangered in Lao PDR (Thomas et al. 2006). It is estimated that only 11-15% of A. crassna habitat is protected in Lao PDR (Rose 2013). The Viet Nam Seed Tree Project established a conservation seed orchard (Loc and Luu 2002).
Aquilaria crassna population needs to be monitored if the impact of agarwood trade is to be accurately determined. Furthermore in order to regulate the trade of A. crassna more effectively species identification procedures need to be implemented at the point of harvest and when it is being exported/imported. |
