How Precise Can Wood Identification Be? Wood Anatomy’S Role in Support of the Legal Timber Trade, Especially Cites

IAWAGasson Journal, — Wood Vol. anatomical 32 (2), 2011: identification 137–154 137 HOW PRECISE CAN WOOD IDENTIFICATION BE? WOOD ANATOMY’S ROLE IN SUPPORT OF THE LEGAL TIMBER TRADE, ESPECIALLY CITES Peter Gasson Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, United Kingdom [E-mail: [email protected]] SUMMARY Traditional wood identification techniques using light microscopy are usually sufficient to identify a wood sample to the genus level. In some cases CITES legislation requires identification to species level, which is difficult or impossible using traditional light microscopy. This paper concentrates mainly on the identification challenges posed by CITES, particularly with ramin (Gonystylus spp.), Brazilian Rosewood (Dal- bergia nigra) and Agarwood (Aquilaria and Gyrinops species). All the other CITES listed timbers and some other taxa that are traded or confused with protected species and might in the future be protected by legislation are also discussed. There are several new non-anatomical techniques being tried to make more accurate identifications and these are mentioned where appropriate. There is a mismatch between legislation and the natural world, and the limitations of the identification process need to be better appreciated by enquirers, especially in relation to CITES enquiries, since species and genus concepts vary among biologists, and can be ambiguous. Key words: CITES, phytochemistry, Gonystylus, Dalbergia nigra, Aquilaria, Gyrinops. INTRODUCTION The precision with which a wood sample can be identified depends on how much sup- porting information is linked to it, how accurate that information is, and the identity of the sample (some taxa have a much narrower geographical range than others so as- sumptions can be made regarding identity). Wood identification queries can be broken down into the following questions: what is it, where is it from (this may be known), what are its properties (or more often what can it be used for), is it from a sustainable source, and is it endangered and/or protected? In the Jodrell Laboratory at Kew we receive wood samples for identification from a wide range of inquirers including the police, Customs/Border Agency, medical practitioners and veterinarians, food manufacturers, archaeologists, palaeontologists, antique dealers, furniture restorers, and the general public. Inquirers are usually satisfied with an identification to the genus level, which is what most wood anatomists would aspire to. In some parts of the world, such as Britain, this is often sufficient to narrow Downloaded from Brill.com09/26/2021 11:42:02PM via free access 138 IAWA Journal, Vol. 32 (2), 2011 down the possibilities to only one or very few species in an archaeological inquiry or where the wood is known to be native (in the U.K. we have only one native species of Alnus, one Fraxinus, one Fagus, two Quercus etc.). The supplementary question of where a wood sample is from can be much more difficult or impossible to answer. Several examples will suffice. The white oak (Quercus sp.) used to make a piece of furniture could come from Europe, Asia or North America. An antique dealer may be particularly interested in where the piece was made because it could greatly affect its value, and often the style of the object helps. This question of provenance is now even more difficult to answer with modern furniture, where oak and ash grown in Russia can be exported to China, made into furniture, and then exported worldwide. International trade in timber and introductions of species for plantation forestry have also contrib- uted to the problem of ascertaining geographical origin. The true mahogany (Swietenia species) which originated in South and Central America is now grown in plantations elsewhere (e.g. in SE Asia, see PROSEA 5(1)), Rubberwood (Hevea sp.) would have had to come from South America until the 1860s but is now grown across the tropics and is increasingly being used for furniture from Malaysia, and Teak (Tectona grandis), which originated in SE Asia now grows in other parts of the tropics e.g. Africa and Latin America. Eucalyptus, originating in Australia is now grown virtually worldwide, having displaced many natural ecosystems. Whereas anatomical techniques cannot always ascertain origin, the use of stable isotopes may provide the answer. Kagawa et al. (2010) and Kagawa & Leavitt (2010) have shown that this is possible with pinyon pines (Pinus edulis and P. monophylla) in the southwest USA and teak (Tectona grandis) in southeast Asia. For some inquirers the identity of the wood is the first stage in finding out its properties, and more pertinently for most, what it can be used for. The properties of a piece of wood can of course be assessed without knowing what it is or where it is from. Den- sity can be broadly assessed in the hand, and microscopic examination can reveal the presence of, for example silica bodies that affect working properties. This supplementary question will not be considered further. Whether timber supply is sustainable is contentious. We have all seen adverts stating that for every tree chopped down three more are planted, which doesn’t necessarily mean that even one of them will reach the size, maturity and quality of the one removed. It also avoids the question of whether the plantation involved is on land where native forest was cleared first. Forestry in temperate regions using native species has in my opinion a greater chance of approaching sustainability than in the tropics. There are fewer species, several of which can be grown in monocultures, and habitat destruction seems to be less severe, or at least less obvious. With time, peoples’ perceptions of what is natural can change, for example the New Forest in Hampshire, England is a mosaic of conifers (introduced except Taxus), broadleaves (many planted) and heathland, and all of it has seen the hand of man over centuries. Tropical forests are nearly all rich in species with relatively few individuals of a given species in a particular area. Removing the diversity and growing monocultures can encourage pests and diseases, especially if the plantation tree is native to the region or a pest has been brought with it. Hevea (pers. obs.) and Khaya (Ebanyenle, pers comm.) are two examples of species grown in Downloaded from Brill.com09/26/2021 11:42:02PM via free access Gasson — Wood anatomical identification 139 plantations that often do not meet yield expectations. Introducing a species can also be problematic if it becomes invasive (various legumes, and see Cedrela mentioned later) or replaces a diverse ecosystem with a monoculture (e.g. Eucalyptus, Pinus radiata). The final question on whether a species is endangered or protected has been the focus of much effort in recent decades with a realisation that some species are being driven towards extinction by over-exploitation. This is a particular problem in the tropics where there may be high species diversity but relatively few individuals of a valuable tree species. Removing these trees not only reduces the size of the population, but there is much collateral damage to the surrounding trees and habitat. Many animals and plants including timber trees now have IUCN red data assessments (see www.iucnredlist.org), which attempt to quantify their rarity. Relatively few of these species have the protection that CITES listing and legislation is intended to provide. There are three levels of CITES protection which are summarised in Appendix 1 from the CITES website (www.cites.org). The choice of taxa on CITES is subjective. Although specialists are consulted about the practicality of listing a taxon, the final choice is politically motivated, and in many cases causes problems for the people charged with policing the legislation. The initial burden falls on Customs officers at a port of entry, and for timbers this is usually a sea port. They have little trouble recognising tiger, leopard and crocodile skins, but a large shipment of reddish brown wood could be the true mahogany Swietenia sp. (CITES Appendix 2) or a less well protected species that looks very similar such as Khaya or Entandrophragma from Africa or a dipterocarp from SE Asia. With large container ports, policing timber imports is a daunting task, and clues such as the port of origin and irregularities in paperwork are often an indication that timber may be being illegally imported. Some customs officers are proficient at accurate identification of some timbers, but they nearly always need to consult an “expert” to be certain that their suspicions are correct. They often only want to know whether a wood sample is a particular taxon, and not what it is if it’s not that taxon. There are several resources that support customs officers charged with enforcing CITES. The CITES Identifica- tion Guide – Tropical Woods (Miller & Wiedenhoeft 2002) allows the recognition of CITES listed timbers using a handlens, and includes some of the pitfall taxa that are not covered. The software programme CITESwoodID version 2.0 (Richter et al. 2008; Koch et al. 2011) does a similar job. In the UK we have produced three posters for display in Customs staff rooms highlighting timber imports of Gonystylus, Pericopsis and Swietenia (Groves 2003; White et al. 2003a, b). Most of this paper will be concerned with discussing the ease or difficulty of identifying the hardwood and softwood taxa on the CITES appendices (annexes in the European Union). These are listed here under the three appendices and discussed later in their taxonomic groups. A separate microscopic atlas of all CITES-listed hardwood and softwood trees is included in this issue (Gasson et al. 2011). Appendix 1 hardwoods: Dalbergia nigra (Leguminosae, Papilionoideae), Balmea stormae (Rubiaceae). 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