Fragmentation influences the diversity of riparian vegetation in the eastern Amazon

Fragmentation is a consequence of anthropic actions that cause changes in land use and cover. Owing to the conversion of forest areas into agricultural use areas, riparian vegetation becomes susceptible to the effects of fragmentation. This generates changes that affect the structure and composition of vegetation in the forest remnants. Therefore, this study aimed to analyze the structure and floristic composition of riparian vegetation with 30 m in a fragmented matrix. Accordingly, adult vegetation (DBH ≥ 5 cm) and regeneration (height ≥ 10 cm, diameter <5 cm) in 10 x 30 m plots were sampled in three stretches of riparian vegetation, two stretches in a pasture matrix and one stretch in matrix with native vegetation. Compared to the area with matrix of native vegetation, the vegetation of riparian areas immersed in pasture matrix showed a floristic composition dissimilarity and some structural similarity. In the regeneration, a high abundance of the species Olyra cf. ecaudata Döll (Poaceae) and Asplenium cf. inaequilaterale Willd. (Aspleniaceae) was observed. Our results provide evidence that the structure of riparian areas with 30 m in the pasture matrix was preserved. However, the performance of the ecological functions of riparian vegetation could be affected over time due to the effects of fragmentation that are influencing the diversity of these areas.