An assessment of the floristic composition, structure and possible origin of a liana forest in the Guayana Shield

Liana is a life form that possesses high importance in many Neotropical forests. Density of climbers apparently increases with the intervention rate (e.g. logging). The aim of this work is to characterize the structure, floristic composition and soils of a sector classified as Liana Forest (LF). We identified an LF sector in a not-logged area; three 1 ha square plots were measured (individuals >= 10 cm dbh, "diameter at breast height"). In each plot, we evaluate four 100 m(2) square understory subplots (all spermatophyta individuals <10 cm dbh). LF has a low canopy (<15 m) and is dominated by Alexa imperatricis and Pentaclethra macroloba. Basal area (20.4m 2 ha 21) and diversity (H' = 2.6) are lower than other surrounding plots. Understory is dominated by gnarled climbers, and the most important are Cheiloclinium hippocrateoides and Bauhinia scala-simiae. Soil is extremely acidic, with very low fertility but is similar to neighboring places. We conclude that LF was neither originated by edaphic restrictions nor logging; LF probably suffered a hurricane wind that fell down most of the canopy trees, thick individuals of climber species also disappeared, and the current successional stage favors a recovery dominated with thin individuals of this life form.