Phytosociology of a monodominant flooded forest of Vochysia divergens Pohl (Vochysiaceae) in North Pantanal, Mato Grosso State, Brazil

Monodominant forest formations of Vochysia divergens Pohl found in the Pantanal are called "Cambarazais". The climatic changes registered in pluri-annual cycles have been cited as responsible for the sudden spread of these formations into seasonally flooded open areas. This study was carried out at the SESC Pantanal RPPN (Private Natural Heritage Reserve), Barão de Melgaço, Mato Grosso (Brazil), as part of the Long Term Ecological Research Program (PELD). It aims to analyze structural and phytosociological data collected in four areas of one hectare each of "cambarazal" along a hydro-topographical gradient. All individuals with cbh (circumference at breast height) ≥ 5cm were identified, perimeters were measured and heights were estimated. In the entire sample area, 3,149 individuals belonging to 83 species were registered. Species diversity along the gradient showed an inverse relationship with floodwater levels. The plot with the lowest level of flooding (P1) had the highest species diversity index (H′ = 2.91) of the sampled plots and the lowest values of V. divergens density and dominance. The other plots were considered to be V. divergens monodominant formations, since relative dominance of this species in these areas was greater than 50%.