HIGH TREE ALPHA-DIVERSITY IN AMAZONIAN ECUADOR

In a 1 ha square plot of terra firme forest at 260 m elevation in Amaz onian Ecuador, all trees with diameter at breast height (dbh) greater- than-or-equal-to 5 cm were studied. There were 1561 individuals, 473 s pecies, 187 genera and 54 families. Of these, 693 individuals, 307 spe cies, 138 genera and 46 families had a dbh greater-than-or-equal-to 10 cm. This is the highest number of tree species ever recorded for a tr opical rain forest sample of this size. In both dbh classes, the most species-rich families were: Fabaceae sensu lato (including Mimosaceae and Caesalpiniaceae), Lauraceae and Sapotaceae; the most species-rich genera. were Pouteria, Inga and Protium. The vertical space was partit ioned among species: 166 species were found only in the 5-10 dbh cm cl ass and were mostly sub-canopy treelets, and 307 species with dbh grea ter-than-or-equal-to 10 cm were mostly large canopy trees.