Floristics of bamboo-dominated stands in lowland terra-firma forests of southwestern Amazonia

We investigated distinctive aspects of the floristic communities associated with bamboo dominance (Guadua sarcocarpa and Guadua weberbaueri) in terra-firma forests of the Tambopata River watershed, southeastern Peru. Data were collected at five sets of paired plots (five bamboo-dominated, five tree-dominated) in which no evidence of prior human disturbance was identified. Three components of the plant community were analyzed: (1) trees ( >= 5 cm diam), (2) tree saplings (< 5 cm diam), and (3) large understory plants (shrubs and herbs >= 1.5 meters). We used three statistical techniques (DCA, TWINSPAN, and ANOVA) to identify distinct assemblages of genera associated with the presence/absence of bamboo, and/or other factors (e.g., soil drainage, geographic location). All three statistical techniques produced similar results: the presence of bamboo is associated with a distinctive floristic community of trees and understory plants, but the tree sapling component of the plant communities was not distinct. Species richness in bamboo-dominated stands, as compared with tree-dominated stands, was 60% lower for trees and 36% lower for understory plants, but not significantly different for tree saplings. Bamboo-associated canopy trees and understory plants were characterized by fast growth rates, tolerance of poorly drained soils, and capacity for vegetative re-sprouting in response to physical damage to stems. These results suggest that differences in both soil and disturbance regimes drive floristic differences between bamboo-dominated stands and adjacent stands without bamboo.