Macroscopic anatomy as a strategy for recognizing commercial wood from the Brazilian Amazon

Abstract

Wood anatomical characterization is a key method for species identification and for combating illegal logging. This study aimed to provide a detailed macroscopic anatomical characterization of twelve wood species from the Brazilian Amazon, supporting species identification in forensic analysis and contributing to educational resources in wood anatomy. The samples were collected from a sawmill in Colniza, northern Mato Grosso, Brazil. Three woods were identified at the species level, and nine were identified at the genus level. Cedrela sp., Hymenaea sp., Hymenolobium sp., Handroanthus sp., and Peltogyne sp. presented well-demarcated growth rings. Diffuse porosity was common, except in Cedrela sp. In Manilkara sp., vessels occurred in radial chains, whereas Handroanthus sp. was notable for pore obstructions caused by a yellowish substance. The main parenchyma type was aliform and/or confluent, along with marginal bands. Six species displayed storied rays. Macroscopic analysis proved effective for wood identification, as parenchyma, vessel, and growth-ring features were sufficient to identify these commercial species at the genus level.

Full Article

Macroscopic Anatomy as a Strategy for Recognizing Commercial Wood from the Brazilian Amazon

Waldelaine R. Hoffmann  ,^a,* Camila M. Campos  ,^a Michelly C. Stragliotto  ,^b Aylson C. Oliveira  ,^a and Bárbara L. C. Pereira  ,^a,*

Wood anatomical characterization is a key method for species identification and for combating illegal logging. This study aimed to provide a detailed macroscopic anatomical characterization of twelve wood species from the Brazilian Amazon, supporting species identification in forensic analysis and contributing to educational resources in wood anatomy. The samples were collected from a sawmill in Colniza, northern Mato Grosso, Brazil. Three woods were identified at the species level, and nine were identified at the genus level. Cedrela sp., Hymenaea sp., Hymenolobium sp., Handroanthus sp., and Peltogyne sp. presented well-demarcated growth rings. Diffuse porosity was common, except in Cedrela sp. In Manilkara sp., vessels occurred in radial chains, whereas Handroanthus sp. was notable for pore obstructions caused by a yellowish substance. The main parenchyma type was aliform and/or confluent, along with marginal bands. Six species displayed storied rays. Macroscopic analysis proved effective for wood identification, as parenchyma, vessel, and growth-ring features were sufficient to identify these commercial species at the genus level.

DOI: 10.15376/biores.20.4.10300-10327

Keywords: Wood identification; Growth rings; Axial parenchyma; Hardwood

Contact information: a: Graduate Program in Forestry and Environmental Sciences, Federal University of Mato Grosso, Mato Grosso 78060-900, Brazil; b: Laboratory of Wood Technology and Bioproducts, Federal University of Western Pará, Pará 68040-255, Brazil; *Corresponding authors: waldelaine-hoffmann@hotmail.com (W.R. Hoffmann); barbara.pereira@ufmt.br (B.L.C. Pereira)

Graphical Abstract

INTRODUCTION

The Amazon Forest is the largest continuous tropical forest in the world (Hoang and Kanemoto 2021) and is considered a biodiversity hotspot, representing one of the main macroregions in Neotropical studies (Andrade-Silva et al. 2024). This forest accounts for more than 10% of the global terrestrial biodiversity (Flores et al. 2024) and performs essential ecosystem functions, such as ecological activities, nutrient cycling (Andrade-Silva et al. 2024) and climate regulation (Armstrong McKay et al. 2022). It also acts as an important carbon sink, storing an amount of carbon equivalent to 15 to 20 years of global CO₂ emissions (IPCC 2021; Meunier et al. 2024). Brazil contains the largest portion of the Amazon, covering 4.3 million km² (60% of the forested area), but it also faces the highest rates of deforestation and degradation, mainly due to land use change, agriculture, livestock, and illegal logging.

Illegal logging currently represents one of the main obstacles to the sustainable use of the Amazon forest (Duarte et al. 2021). This has been widely discussed in the context of the conservation of this tropical forest (Pereira et al. 2020; Flores et al. 2024). The misidentification of species impacts the commercialization and conservation of tropical wood, highlighting the need for precise studies to protect biodiversity and strengthen legal trade (Souza et al. 2020). In view of this, the implementation of legislation related to the prohibition of illegal deforestation and the commercialization of Amazonian wood without traceability has led to the creation of tools to identify and verify the origin of the wood at inspection posts (Ferreira et al. 2023). Among these methods, wood anatomy stands out as a traditional method that has been widely used for the identification of tree species in the scientific community (Ferreira et al. 2023).

Macroscopic anatomical analysis is one of the most widely used techniques for species identification (Souza et al. 2020; Duarte et al. 2021). It allows the evaluation of structures, contributing to the identification of Amazonian tree species. Despite its efficiency, anatomical identification faces challenges in tropical regions because of the high diversity of species and wide anatomical variation. Its practical application can also be limited by the need for trained professionals and reliable databases of previously identified species (Lens et al. 2020; Ferreira et al. 2023). In addition, given the variety of anatomical features among the evaluated species, the dataset generated in this study can serve as valuable didactic material in wood anatomy courses, supporting the training of students and professionals. Nevertheless, macroscopic characterization remains faster and less complex than microscopic approaches (Alves et al. 2023).

Therefore, the aim of this study was to provide a detailed macroscopic anatomical characterization of twelve commercial wood species from the Brazilian Amazon, supporting species identification in forensic analysis and contributing to the development of educational resources in wood anatomy.

EXPERIMENTAL

Study Area and Sample Collection

Twelve Amazonian wood species were evaluated and collected from a sawmill located in Colniza, northern Mato Grosso, Brazil, within the Brazilian Legal Amazon region (Fig. 1).

Fig. 1. Location map of the collection region of the studied species, also showing temperature and precipitation

The region has an average annual rainfall of 2373.6 mm and an average temperature of 26.6 °C (Zepner et al. 2020), with an Am climate according to the Köppen-Geiger classification, with a short dry season and a monsoon influence (Aparecido et al. 2020). In the storage yard, three heartwood rafters (5.0 × 5.0 × 200.0 cm), free of defects, were randomly selected per species from a batch totaling 5 m³. For each rafter, a 2 × 3 × 5 cm sample was prepared for macroscopic wood characterization. The wood identification was initially based on local commercial names used by the sawmill (Table 1).

Table 1. Commercial and Scientific Names of the Brazilian Amazonian Timber Species Analyzed

 Note: *The Wood Database (2024).

Macroscopic Characterization

The samples were sequentially polished with sandpapers ranging from 80 to 2000 grit (Fig. 2). Then, they were brushed to unclog the vessels. A stereomicroscope was used for anatomical characterization to characterize the distinguishing features of the growth ring limits, vessels (visibility, porosity, grouping, arrangement and content), axial parenchyma (visibility and disposition), and rays (visibility in the transverse plane; contrast in the radial plane; and storied rays in the tangential plane) (Fig. 2), according to COPANT (1974), the IAWA Committee (1989), Ruffinatto et al. (2015) and Latorraca et al. (2018).

Fig. 2. Scheme of the procedures adopted for the macroscopic characterization of 12 commercial wood species from the Brazilian Amazon: (A) sample preparation; (B) image capture

The species characteristics were subsequently recorded through images captured in the transverse, tangential, and radial planes using a Leica M205C stereomicroscope equipped with a photomontage system (Fig. 2) and a 1 mm scale. The identification was confirmed by comparison with wood deposited in the Wood Collection of the Institute of Agricultural Defense of Mato Grosso (INDEA/MT), located in Cuiabá, Mato Grosso, Brazil.

Considering that the evaluated woods are traded in both domestic and international markets, lists of endangered species were consulted to assess the level of exploitation of the genera and their representatives. For this analysis, the following main reference sources were consulted: the List of Endangered Species in Brazil, the IUCN Red List of Threatened Species, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Brasil 2022; IUCN 2024; CITES 2024).

RESULTS AND DISCUSSION

In this study, the genera corresponding to the trade names were confirmed through macroscopic identification (Fig. 3), with the observed genera matching the common names assigned to the species in the region, as noted by Schmitz et al. (2020).

Fig. 3. Transverse plane of twelve commercial wood samples from the Brazilian Amazon at lower magnification, highlighting color, patterns, and growth rings: (A) Amburana acreana; (B) Cedrela sp.; (C) Hymenaea sp.; (D) Hymenolobium sp.; (E) Apuleia leiocarpa; (F) Handroanthus sp.; (G) Astronium sp.; (H) Guarea sp.; (I) Simarouba amara; (J) Peltogyne sp.; (K) Manilkara sp.; (L) Bowdichia sp. The black arrows on the left side of each image indicate the growth rings. A representative scale (white bar) equivalent to 1 mm is shown.

Macroscopic characterization provides important diagnostic features for wood identification; however, distinguishing species within the same genus can be particularly challenging when it is based solely on wood characteristics. Six botanical families were identified, with Fabaceae comprising 50% of the samples, followed by Meliaceae (16.7%), and the remaining families with one representative (8.3%). Twelve species were evaluated, three of which were identified at the species level, and the remaining nine were identified at the genus level. Macroscopic wood identification is usually supported by background information, such as the approximate harvest location (Schmitz et al. 2020). Such information considerably reduces the number of taxa to be assessed. In this study, this was the case for Amburana acreana and Simarouba amara.

Figure 4 also presents the transverse plane at a higher magnification, allowing clearer visualization of the axial parenchyma and vessels. The tangential plane of woods with storied rays is shown in Fig. 5, whereas non-storied rays are illustrated in Fig. 6. The ray flecks and contrasts in the radial plane are presented in Fig. 7.