Flower Survey of Tree Species of Riparian Vegetation in Astorga, Brazil

Abstract

The floristic composition and successional stage of tree species in riparian vegetation of the Ribeirão da Içara (23º09’51.74’’S and 51º39’21.60’’W) in the municipality of Astorga in the northern region of the state of Paraná, Brazil, are analyzed. Climate is Cfa and average altitude is 532 m. The 0.5 ha area under analysis belongs to the Semideciduous Seasonal Forest and consists of a stretch of riparian vegetation formed by native vegetation with dense tree groups, creepers, ground vegetation and reforestation. Surrounding ground is occupied by livestock and the production of sugar cane and orange trees. Botanic material was collected by 3-day monthly expeditions between December 2010 and March 2011. Tree specimens in the reproduction stage were sampled and voucher specimens were incorporated to the collection of the State University of Maringá. Only the vegetal parts of some species were collected and the material was identified by specific bibliography and compared with specimens at the university, following the APG III system. Species were classified with regard to their successional stage by specific bibliography and field observations, although exotic and indeterminate plants were not taken into account in current analysis. Eighty-four species, with 77 genera and 28 families, were registered. Six were identified at genus level, four at family level and one family was undetermined. The Fabaceae had the highest number of species (23), followed by Myrtaceae (6), Malvaceae and Meliaceae (5), Anacardiaceae, Bignoniaceae, Euphorbiaceae and Sapindaceae (4), Rutaceae (3). Further, 69.05% of species belong to these families. Machaerium (3) was the genus with the highest number of species. With regard to the successional stage, 35.93% were species of the pioneer succession class; 32.81% initial secondary class; 20.31% late secondary class and 0.44% climax class. Results, featuring predominantly pioneer and secondary species, show a gradual replacement of species, perhaps related to the removal of commercially relevant species.