Relationships of epiphytic bromeliads with environmental factors at Iguaçu river floodplains, Parana, Brazil

Abstract

A total of 14 epiphytic bromeliad species have been recorded at Iguaçu river floodplain, some being exclusive to the Ombrophilous Dense Forest, others to the Semideciduous Seasonal Forest, and one third group common to the two vegetation types. The species number decreased downstream along the river, in coherence to the equivalent reduction in the water availability defined by the climatic types. The degradation geomorphic surfaces presented the highest diversity indexes, which can be associated to the longest developing time of these geomorphic features and the presence of non-hydromorphic and semihydromorphic soils. In local scale, the maximum width of the floodplain and the average width of the river are negatively correlated with bromeliad richness, which is associated to strong anthropogenic disturbance. The proximity of the phorophytes with the river influenced positively bromeliad richness, probably, through the humidity and luminosity increment. At the same way, the phorophytes with the largest diameters presented greater richness of bromeliads, indicating, principally, that the time of exposition of substrate is important, what agrees with literature. The maintenance of forests close to streams and large trees is fundamental to epiphytic bromeliad conservation purposes at Iguaçu river floodplains.