CharKey: An electronic identification key for wood charcoals of French Guiana

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Tropical tree floras are highly diverse and many genera and species share similar anatomical patterns, making the identification of tropical wood charcoal very difficult. Appropriate tools to characterize charcoal anatomy are thus needed to facilitate and improve identification in such species-rich areas. This paper presents the first computer-aided identification key designed for charcoals from French Guiana, based on the wood anatomy of 507 species belonging to 274 genera and 71 families, which covers respectively 28%, 67% and 86% of the tree species, genera and families currently listed in this part of Amazonia. Species of the same genus are recorded together except those described under a synonym genus in Détienne et al. (1982) that were kept separately. As a result, the key contains 289 ‘items’ and mostly aims to identify charcoals at the genus level. It records 26 anatomical features leading to 112 feature states, almost all of which are illustrated by SEM photographs of charcoal. The descriptions were mostly taken from Détienne et al.’s guidebook on tropical woods of French Guiana (1982) and follow the IAWA list of microscopic features for hardwood identification (Wheeler et al. 1989). Some adjustments were made to a few features and those that are unrelated to charcoal identification were excluded. The whole tool, named CharKey, contains the key itself and the associated database including photographs. It can be downloaded on Figshare at (doi: 10.6084/m9.figshare.6396005). CharKey is accessible using the free software Xper2, specifically conceived for taxonomic description and computer aided-identification.

CharKey: An electronic identification key for wood charcoals of French Guiana

in IAWA Journal



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    – a: Number of genera per family in CharKey compared with the updated checklist of Molino et al. (unpublished data). Menispermaceae (rank 71) are not in the checklist because they do not reach a dbh ≥ 10 cm. – b: The genera absent from the checklist, corresponding to ranks 271 to 274, are Artocarpus, Gmelina (both introduced), Abuta and Machaerium (lianas with a dbh < 10 cm). The detailed lists of genera and species with their ranking can be found in the Supplementary Material.

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    – a: Appearance of CharKey under Xper2 when launched. When the user clicks on a descriptor (1) its states appear in the top right window and its definition in the bottom left window. The pictures illustrating each state can be seen by clicking on one of them (2), then on the “Image” tab (3). To start the identification process, click on “identification” in the tool bar at the top of the screen (4). – b: Identification window. To start the process, select a descriptor (5) and at least one state (6). Note that the logical operator can be chosen (7). When the user clicks on “submit” (8), the list of taxa corresponding to the selected features appears in the top right window. Click on one of them (9) to see the list of species in each genus present in French Guiana. Throughout the process, the mismatch threshold can be changed in the options (10) and the selected features can be seen and removed one by one by clicking on the “Description in progress” tab (11). The current search can be closed and a new identification started by pressing the “Reset” button (12).

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    Transverse (a), tangential longitudinal (b, e) and radial longitudinal (c, d) sections of Recordoxylon speciosum (Caesalpinioideae). – a: Parenchyma mostly aliform and confluent. – b: 2-seriate rays, some of which have uniseriate marginal portions (arrows). – c: Homogeneous rays. – d: Vessel-ray pits similar to intervessel pits in shape and size. – e: Intervessel pits vestured.

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    Transverse (a), tangential longitudinal (b, c) and radial longitudinal (d, e) sections of Bixa orellana (Bixaceae). – a: Parenchyma diffuse-in-aggregates. – b: Intervessel pits vestured. – c: 2-seriate rays with low rays and parenchyma storied. – d: Heterogeneous rays. – e: Vessel-ray pits similar to intervessel pits in shape and size.


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