The present study focusses on the application of 3D-reflected light microscopy (3D-RLM) for the wood anatomical identification of charcoal specimens produced from domestic and tropical timbers. This special microscopic technique offers a detailed investigation of anatomical features in charcoal directly compared with the quality of field emission scanning electron microscopy (FESEM). The advantages of using the 3D-RLM technology are that fresh fracture planes of charcoal can be directly observed under the microscope without further preparation or surface treatment. Furthermore, the 3D-technique with integrated polarized light illumination creates high-contrast images of uneven and black charcoal surfaces. Important diagnostic structural features such as septate fibres and intercellular canals can be clearly detected and intervessel pits are directly measured. The comparison of the microscopic analyses reveals that 3D-reflected light microscopy (3D-RLM) provides an effective alternative technique to conventional field emission scanning electron microscopy for the identification of carbonized wood.
Molecular research has shown that the genus Acacia is in fact polyphyletic. The discussion about grouping the species of Acacia s.l. into monophyletic genera kept two International Botanical Congresses (Congresses 17 and 18) occupied and resulted in the general acceptance of the genera Acacia, Acaciella, Mariosousa, Senegalia and Vachellia. This raises questions about whether the wood of these new genera can be distinguished using established wood identification methods. Anatomical features of members from Acacia, Acaciella, Senegalia and Vachellia were examined and compared using transmission light microscopy. Topochemical characteristics were investigated using UV microspectrophotometry (UMSP) to identify differences in the distribution of phenolic compounds and cell wall lignification. The current study shows that the presence as well as the arrangement and dimensions of the axial parenchyma, as well as the height and width of the wood rays and fibre dimensions allow anatomical differentiation of the species studied. UMSP revealed the presence and distribution of phenolic compounds and differences in the degree of lignification between the genera. The aim of this paper is to highlight the potential of the applied methods to differentiate between the genera.
The present study focuses on the application of state-of-the-art μCT, by using a sub-micrometre CT scanner as a tool for wood identification. Charcoal was chosen as a subject for this case study. The reason for choosing charcoal is based on economic as well as technical issues. Parallel to conventional wood anatomy, various promising approaches to identification are currently being developed worldwide in order to simplify the identification of processed wood. However, due to the carbonization process, such approaches are not applicable to charcoal. In view of the rapid development of μCT technology, it was decided to examine the extent to which wood anatomical studies can be supported and improved by modern μCT technology. About 17% of the annually harvested wood worldwide is converted to charcoal (FAO 2017), and the charcoal trade is one of the least controlled/monitored segments of the European timber market. Although charcoal has a significant market share of wood-based products, it is still not yet covered by any trade regulation, e.g. the European Timber Regulations (EUTR), (EU) No995/2010. For the present study, different wood types and the anatomical fine structural features were measured and displayed at different magnifications to visualize the performance of state-of-the-art μCT standards. Three different charcoal assortments were examined, and the results were checked against the given declarations of contents. The aim of this work is to evaluate the potential of the μCT technique in the field of wood identification and to assess its use for the regulatory control of charcoal and other wood products in the international timber trade. The results are encouraging and lead to the conclusion that the application of the μCT technique in the field of wood identification can be classified as very promising for the future.
Anatomical and subcellular characteristics of juvenile and adult wood of seven species (Manilkara zapota (L.) P. Royen, Platymiscium yucatanum Standl., Lonchocarpus castilloi Standl., Roseodendron donnell-smithii (Rose) Miranda, Terminalia buceras (L.) Wright, Tabebuia rosea (Bertol.) DC., Lysiloma latisiliquum (L.) Benth. from Mexico, including a histometric evaluation, were investigated by light microscopy with a digitized image analysis system and by X-ray diffractometry using the SilviScan® system. The topochemical distribution of lignin and phenolic deposits in the tissue was studied by means of cellular UV-microspectrophotometry (UMSP). Extractive contents (acetone/water and water) were determined gravimetrically. The results of the structural and topochemical analyses were compared with the interrelations of certain anatomical and subcellular structures as well as the topochemical composition with regard to the physical and mechanical properties of the timbers investigated. The objective was to provide a detailed cellular and subcellular description of the heartwood of seven lesser-known timbers from Central America. All examined tree species show significant differences between juvenile and adult heartwood. For individual species, however, the differences vary greatly and have to be individually assessed in addition to general trends observed for all studied species. It has been shown that vessel size, fibre length, size of fibre lumina, and height and width of rays, as well as the content of extractives and topochemical composition of the cell walls, are suitable indicators for the differentiation of the two heartwood types. The results also contribute to a better understanding of the wood properties of the investigated timbers in relation to their utilization and added value increase.
About half the wood extracted worldwide from forests is used as fuelwood to produce energy, about 17 percent is converted to charcoal (FAO 2017) which represents one of the least controlled/monitored segments of the European timber market. Although charcoal has a significant share on the European market of wood-based products it is not yet covered by the European Timber Regulations (EUTR), (EU) No 995/2010. For this project, a total of 150 charcoal consignments from eleven countries (Germany, Poland, Switzerland, Spain, Italy, Norway, Denmark, Netherlands, Ukraine, Czech Republic, and Belgium) were examined and evaluated based on the 3D-reflected light microscopy technique. The high-resolution study indicates the proportion of different European timbers compared with that of timbers from subtropical and tropical regions. The share of subtropical and tropical species is surprisingly high with approximately 46% for material received from all countries studied, but far over 60% for Spain, Italy, Poland, and Belgium. The study shows that comparing the results for charcoal received from these countries there is an inversely proportional relation of certified products (FSC and PEFC) and products with timbers from subtropical or tropical origins. In the charcoal consignments from Switzerland, the share of timbers from subtropical or tropical origin is only 13.5%, whereas that of certified products is 60%. In material received from Spain, the proportion of timbers from subtropical or tropical regions is 67%, whereas that of certified products only 8%. A careful check of the declaration on the packaging, of the accompanying certificates, and the information on origin revealed alarming evidence: only 25% of the consignments examined provide information on the bags, e.g., with regard to the processed wood species; and well over half of such declarations were incorrect and/or incomplete. A trade flow analysis of EU member states was carried out to contribute to a better understanding of the relationships between international charcoal trade flows and the end products in European countries. This approach contributes to an essential understanding of charcoal transit in Europe and the results constitute a strong motive for the inclusion of charcoal in the respective annex to the EUTR.
Illegal logging and illegal timber trade is a global problem. Anatomical, genetic, and chemical techniques support illegal logging legislation by verifying the species and geographic origin of timber. In principle, these methods can be used to identify timber species and the origin of harvest, however, the availability of specific tests for important timber species is unclear. We review the status of these methods for the top 322 global priority timber taxa. Our results show that for species identification, reference data exist for 100% of taxa using wood anatomy, 86% using genetics, 41% for using DART TOFMS, and 6% using NIRS. For origin identification, data exist for 24% of taxa, with most studies applying genetic approaches (23%). No studies have developed forensic-ready tests for the global priority timber taxa. The review highlights that the current potential for identifying species is greater than for geographic origin and more research focused on determining the geographical origin of timber is required. Based on the current rate, it will take approx. 27 years to generate geographic data for all 322 priority taxa. Finally, we identify research opportunities to improve global timber tracing efforts. Our findings indicate more research is needed, and quickly so that scientific verification can support regulators to combat illegal logging.