*2.1. Study Site and Sampling*

The tissue samples for DNA extraction were collected from the 20.28 hectares (260 × 780 m) Ngel Nyaki Forest Dynamics plot, where all trees with diameter at breast height (dbh) > 1 cm had previously been measured, mapped tagged and morphologically identified [19]. The plot (07◦04005-- N, 11◦03024-- E) is located within the Ngel Nyaki Forest Reserve on the Mambilla Plateau, Taraba State, Nigeria, with elevation ranging from 1588 m to 1690 m, and is part of the Forest Global Earth Observatory (ForestGEO) network [20]. The mean annual rainfall is 1800 mm while the mean annual temperature is 19 ◦C. The vegetation of the area is a mosaic of grassland and montane forest [21].

The morphological identifications of the trees were performed in the field by nonprofessional taxonomists, but were partially checked by the first author. The resulting checklist comprised 105 morphospecies including 74 (71%) identified to species level, 22 (21%) to genus, and 9 (9%) unidentified, even to family level. Of the 105 species (with dbh > 1 cm) recorded in the Ngel Nyaki plot, we sampled 99 belonging to 90 genera and 47 families. Two additional woody species growing in the vicinity of the plot, *Dracaena* cf. *deisteliana* Engl. (Asparagaceae) and *Pittosporum viridiflorum* Sims (Pittosporaceae), were added to our sample, making a total of 101 species in 92 genera and 48 families. We collected leaf tissue from 1 (for species that were represented by a single individual in the plot) to 4 individuals per species. The samples were collected in the field and were immediately dried in silica-gel. They consisted of 5–50 cm<sup>2</sup> of leaf tissue. Voucher specimens accompanying the leaf tissue were also collected and are deposited at the National Museum of Natural History in Washington.
