The information available from herbarium collections is scarce and access to the wild resources is difficult. The taxonomic status of some Aquilaria species is uncertain. Laos has been a major supplier of high-quality agarwood since harvesting started at the end of the Second Indochina War in 1975. The Lao PeopleвЂ™s Democratic Republic (henceforth Laos) was chosen as case study country because it is the only range State where harvesting of A. The greater part of agarwood comes from the wild. It is used in medicinal, aromatic, ceremonial, and religious preparations and traded across old routes from its natural range States in South-east Asia (Indochina and Thailand) to consumers in the Arab world and in East Asia. ДЄgarwood is traded under many synonyms, for example, eaglewood and gaharu, and in many different qualities of unprocessed wood and essential oil. Not all trees form agarwood under natural conditions. The exact mechanism is not fully understood, and a number of ecological, physiological, and genetic factors may be involved. The production of this oleo-resin, which acts as a chemical barrier to attacks by fungi, insects, and so forth, is apparently a tree response to injury if its primary defence mechanism, the formation of phloem callus tissue, is inhibited. crassna trees as nodules of varying age, shape, size, and commercial quality, embedded in the otherwise pale and soft wood. This will help in facilitating resource assessment, reevaluating conservation status, and overcoming the deficiency of field data on the species.ДЄgarwood is a dark-coloured fragrant resin that accumulates inside stems and roots of A. crassna in harvested populations found within typical habitats at four sites in Northern Laos. The second study objective is to assess the absolute density of A. The basic method used in this study is transect distance sampling. Few methods exist for single species inventory, and only a small number of studies aim at single species in situ. Its first objective is to apply an inventory method to individual tree species occurring at low densities. is classified as вЂњCritically EndangeredвЂќ but with no field data attestation. All species of the genus are listed in CITES, Appendix II, and several species are on the IUCN Red List. Furthermore, reduction of habitat area and excessive, indiscriminate harvesting for agarwood, probably the worldвЂ™s most valuable nontimber forest product (NTFP), are likely to have increased the spatial heterogeneity of populations. Aquilaria populations are widespread but clumped and occur at low densities. Tree species of the genus Aquilaria (Thymelaeaceae) are instructive cases of the difficulties and challenges in assessing population status and harvesting impacts. The quality and detail of data from these sources may be insufficient to accurately assess the status of a particular species, especially tropical taxa with broad distributions, and may cause erroneous assessments and misguided conservation efforts. However, the sources of information used for such assessments are generally limited to flora and taxonomic revisions, herbaria collections, and inventory and mapping exercises. IntroductionДЄccording to a global assessment, roughly 9,000 tree species are threatened with extinction and many species have therefore become the focus of increasing conservation concern. Results of the present case study could suggest that the conservation status of A. The survey method should stand a good chance of wider use as a tool in management and conservation of a wide range of tree species. However, the estimated densities of living saplings, 10.9вЂ‰ha в€’1, small trees (DBH < 10вЂ‰cm), 10.6вЂ‰ha в€’1, and larger trees (DBH в‰Ґ 10вЂ‰cm), 1.7вЂ‰ha в€’1, suggest that populations are not wiped flat. crassna trees at the four sites was 2.2вЂ‰ha в€’1, indicating that harvesting has been extensive. This species is destructively harvested to yield agarwood, probably the worldвЂ™s most valuable nontimber forest product and categorised as вЂќcritically endangeredвЂњ. (Thymelaeaceae) at four sites in Northern Laos. The method was applied to previously harvested populations of Aquilaria crassna Pierre ex H. This paper describes a method for estimation of absolute density of a rare tree species with scattered and clumped distribution, using line transect distance sampling. Use of distance sampling techniques may help to overcome the problem. Lack of reliable and accurate field data affect assessments of population status of tree species, especially tropical taxa with broad distributions.

Distance sampling method