Vegetation communities and their relationship with the pulse regime on islands of the Middle Paraná River, Argentina

Vegetation associated to the Parana River is subject to conditions imposed by the pulse regime. This study aimed to evaluate the pulse regime influence on the vegetation of the Parana River islands. Using multivariate techniques for classification and ordination, six communities were identified and described: willow forests of marginal levees, riverine forest of internal levees, floating meadows, floating rooted plants, a tall grass herbaceous community and a marshy community. The forests were the most diverse and the richest communities while the floating meadows and the marshy community were less rich and diverse. Our results indicate that duration and recurrence of floods are important variables in determining the characteristics of the vegetation. However, forests with a similar flood recurrence and duration showed important differences in physiognomy, structure and floris - tic composition. The differences between the forests could be explained by the connectivity degree, geomorphological dynamics and succession time.