Description de la xylothèque du Cirad à Montpellier, France, regroupant huit mille espèces identifiées

The Cirad wood collection, which was first awarded funding 80 years ago, now consists of specimens from 34,395 trees, 235 families, 2,160 genera and 8,385 species (of which 60% are represented by more than one specimen per tree) from 123 countries. Tropical species from Africa, Asia and South America make up 85% of the collection. Botanical descriptions have been made of the dominant families, genera and species in the ten geographical regions for which there are large enough collections (1,000+ specimens). These regions include nine tropical or subtropical regions and a large entity called “Northern Cold Climate” (NCC), which covers all northern hemisphere countries with a cold season (boreal, alpine temperate and Mediterranean climate). The nine tropical and subtropical regions have more or less the same dominant families but different dominant genera, while dominant families in the NCC entity differ widely. The collection is described in a specific data base: wood specimens, sections and photographs with their name and provenance. Specific Gravity (SG) has been measured in two thirds of all the specimens (6,750 species). Overall, SG values have a near normal distribution ranging from 0.04 to 1.36, with a median value of 0.72 and a 28% coefficient of variation (CV). The difference between regions in specific gravity distribution is quite small (mean values 0.66 to 0.76) with a consistently high CV (26% to 32%). Looking at the best represented families, genera and species, the mean CV for families (26%) is similar across regions and much lower for genera (18%) and species (13%). The SG range increases from family to genus to species (0.53 to 0.86, 0.46 to 0.95, 0.23 to 1.07 respectively). The different current and potential uses of the wood collection are discussed.