RIQUEZA, COMPOSICIÓN Y DISTRIBUCIÓN FLORÍSTICA DE LOS PAISAJES FISIOGRÁFICOS DEL EJE DE LOS RÍOS APAPORIS Y AMAZONAS, AMAZONIA COLOMBIANA
DIEGO GIRALDO-CAÑAS
ABSTRACT: Giraldo-Cañas, D. 1999. Floristic composition, richness and distribution of physiographic landscapes between the Apaporis and Amazonas rivers, Colombian Amazon. Darwiniana 37(1-2): 25-35.
A floristic study on 15 physiographic landscapes in the south of the Colombian Amazon was carried out. In 2.8 ha, 593 vascular plants (dbh ³ 10 cm) were found, belonging to 254 genera distributed among 65 families. Nine families represent 52 % of the total number of species and comprise 65 % of the total number of individuals. The richest families are Fabaceae (78 species, 13%), Chrysobalanaceae (42 species, 7%), Euphorbiaceae (29 species, 5%), Myristicaceae (28 species, 5%), Burseraceae (27 species, 4.5%), Sapotaceae (27 species, 4.5%), Lauraceae (26 species, 4.4%), Moraceae (24 species, 4.1%) and Lecythidaceae (23 species, 4%). The richest genera are Licania (20 species), Protium (18 species), Inga (16 species) and Eschweilera (14 species). Myristicaceae, Euphorbiaceae, Moraceae and Lauraceae are dominant and abundant on well drained soils, while Chrysobalanaceae, Sapotaceae and Sterculiaceae are important families in periodically flooded landscapes. Monopteryx uaucu Spruce ex Benth. (Fabaceae) and Eschweilera coriacea (A. DC.) S. A. Mori (Lecythidaceae) are the most widely distributed species in different landscapes. Plant formations on plio-pleistocenic dissected plains of curved surfaces with acute and rounded summits possess the highest floristic richness; while alluvial plains with intermediate flood level by amazonian rivers show the lowest floristic species richness. Disturbance of the mature forests is caused by geomorphological dynamics, high winds, instability of the river courses, and by human action over thousands of years.
Key words: Amazonia, Colombia, Plant diversity, Amazonian physiographic landscapes, Amazonian forests, Natural disturbance.