LOS BOSQUES INUNDADOS POR AGUAS NEGRAS DE LA AMAZONIA ECUATORIANA

Abstract

Flooded forests by black-water rivers in ecuadorian Amazon are known also as Igapos. Igapos occur at altitudes lower than 400 masl and could be dominated by Mauritia flexuosa palms (Moretales) or not (No moretales). Since 1998 we have sampled 14 igapo sites using 0.1 ha. transects for species with DBH > 2.5 cm. Collected specimens are kept in the QAP Herbarium. We calculated the Simpson Diversity Index and the Sorensen Index of S¡- milarity for all sampling sites. The number of individuáis recorded per sample site ranged from 95 to 301, the species number rangesd from 16 to 75. Overall, 367 species were recorded in the 14 sample sites. Diversity indices point to low or cióse to mean diversities. Similarity indices varied from 2.5 to 50%. In the Moretales Mauritia flexuosa is not always the most common species, other species like Mauritiella armata, Bactris maraja Cinchonia Vol. 7, # 1, 2006 63 var. mar aja, B. corossilla or Helicón ¡a standleyi dominated in some places. In the No moretales the most common species were Zygia inaequalis, Heliconia marginata, Neea divaricata, Rinorea lindeniana, Quararibea guíanensis and Anaxagorea phaeocarpa. The results show that the ecuadorian igapos are heterogeneous, differing in their area, origin, hydric sources and geographic location.