Wood identification of Dalbergia nigra (CITES Appendix I) using quantitative wood anatomy, principal components analysis and naive Bayes classification.
OBJECTIVE
Dalbergia nigra is one of the most valuable timber species of its genus, having been traded for over 300 years. Due to over-exploitation it is facing extinction and trade has been banned under CITES Appendix I since 1992. Current methods, primarily comparative wood anatomy, are inadequate for conclusive species identification. This study aims to find a set of anatomical characters that distinguish the wood of D. nigra from other commercially important species of Dalbergia from Latin America.


METHODS
Qualitative and quantitative wood anatomy, principal components analysis and naïve Bayes classification were conducted on 43 specimens of Dalbergia, eight D. nigra and 35 from six other Latin American species.


RESULTS
Dalbergia cearensis and D. miscolobium can be distinguished from D. nigra on the basis of vessel frequency for the former, and ray frequency for the latter. Principal components analysis was unable to provide any further basis for separating the species. Naïve Bayes classification using the four characters: minimum vessel diameter; frequency of solitary vessels; mean ray width; and frequency of axially fused rays, classified all eight D. nigra correctly with no false negatives, but there was a false positive rate of 36.36 %.


CONCLUSIONS
Wood anatomy alone cannot distinguish D. nigra from all other commercially important Dalbergia species likely to be encountered by customs officials, but can be used to reduce the number of specimens that would need further study.
Gasson
Peter
P
Jodrell Laboratory, Royal Botanic Gardens Kew, Kew Road, Richmond, Surrey TW9 3DS, UK. P.Gasson@kew.org
Miller
Regis
R
Stekel
Dov J
DJ
Whinder
Frances
F
Zieminska
Kasia
K
D001499:Bayes Theorem; D002965:Classification / Q000379:methods; D003247:Conservation of Natural Resources; D035782:Dalbergia / Q000033:anatomy & histology* / Q000145:classification; D025341:Principal Component Analysis; D013045:Species Specificity; D014934:Wood / Q000033:anatomy & histology* / Q000145:classification