Despite their key ecological role and contribution to biodiversity, plant studies in the tropics have tended to ignore the understory components. This study aimed at addressing how richness and composition of understory plants change along an altitudinal range in the tropical Andes. Understory herbs and tree seedlings and saplings up to 2.0 m height were tallied and recorded in fifty 1.5x1.5 m2 –plots evenly spaced at five forest ranging from 1070 to 3000 m altitude
Results/Conclusions
There were a total of 810 individuals belonging to 65 families, 120 genera and 154 species. Species richness did not significantly varied among sites and species composition was significantly different among sites. At the lowest altitude the most abundant families were Marattiaceae (32 ind.), Poaceae (26 ind.) and Araceae (24 ind.). At 1820 m altitude Selaginellaceae (113 ind.) and Blechnaceae were the most common families; at 2050 m Rubiaceae (70 ind.) and Arecaceae (49 ind.) were the most abundant families; at 2200 m the families were Urticaceae (20 ind.) and Rubiaceae (11 ind.). At the highest site the most common families were Oxalicacae (55 ind.) and Asteraceae (52 ind.). Rubiaceae was the only family recorded in all sites but none genus in this family was found in all sites. Miconia (Melastomataceae) and Palicourea (Rubiaceae) were the genera most widely distributed (found in four sites) in the understory. Few genera from other families were found in three or less sites and most genera were exclusive from a given site, highlighting the importance of forest conservation at different altitudes in the tropics. Even though species richness seems not to change with elevation in the gradient assessed, overall species composition does change within it, stressing the high plant diversity in tropical Andes