Seasonal Dynamics of Flooded Tropical Grassland Communities in the Pantanal Wetland

Abstract

We aimed to answer the following questions: do vegetation structure and functional characteristics of grassland types differ between hydrological periods (i.e., aquatic and terrestrial phase) in the Pantanal wetland? What general plant functional traits characterize these communities? We sampled 37 sites in three grassland types in the Cuiaba river megafan, in the northern Pantanal, Brazil, in both the aquatic and terrestrial phases. We determined, from the literature, ‘stable’ plant functional traits, namely life cycle, bud-bank types and, for graminoids, photosynthetic pathway, i.e., characteristics important in tropical habitats with the occurrence of flood, fire and drought. We compared the grassland types in distinct hydrological phases concerning the vegetation structure and functional attributes using Permutation test. We found that all grasslands are dominated by perennials during terrestrial and aquatic phases. Most species bears clonal organs, and aboveground bud-banks are specially relevant to the grassland under long-term flooding. C4 graminoids are dominant but C3 graminoids increase their cover during aquatic phase. Pantanal grasslands are rich in species and showed marked differences in height between terrestrial and aquatic phases. Our results are a basis to devise conservation strategies for grasslands in the Pantanal, susceptible to threats by global change processes.