TREE STRUCTURE AND DIVERSITY OF SECONDARY VEGETATION DERIVED FROM A SEMI-EVERGREEN TROPICAL FOREST IN QUINTANA ROO

The structure and diversity of a semi-evergreen tropical forest in the Andres Quintana Roo ejido, located in the municipality of Felipe Carrillo Puerto, Quintana Roo, Mexico, was analyzed. To this end, six sampling units of 20 x 50 m (1,000 m(2)), two units per tropical forest development condition (age of disturbance), were established: a) forest fire 10 years ago (C10), b) agricultural use 24 years ago (C20) and c) pastoral use 33 years ago (C30). Forest structure was characterized by the diameter and height distribution of individuals in each condition, as well as using the importance value (IVI) and forest value (FVI) indices. Pouteria reticulata was the species with the highest IVI and Ficus sp. had the highest FVI, both in C10 and C20, while Bursera simaruba and Lysiloma latisiliquum obtained the highest WI and FVI, respectively, in C30. Species diversity was evaluated using proportional abundance (Shannon: H') and floristic similarity (Sorensen: IS) indices. Species diversity of seedlings, poles and saplings was higher in C10, C30 and C20, respectively. Poles had on average floristic similarities of 60 % between forest development conditions, while seedlings and saplings had less than 50 %.