Calculation of Functionnal Diversity according to the Oikos paper : Mouchet M., Guilhaumon F., Villéger S., Mason N., Tomasini J. A., Mouillot D. Towards a consensus for calculating dendrogram-based functional diversity indices. 2008. OIKOS (Volume 117 Issue 5, Pages 794 - 800) Code by François Guilhaumon ([email protected]) Xtree, Getlength.inner and Getlength functions by Owen Petchey ([email protected])