Influência dos fatores hidro-edáficos na diversidade, composição florística e estrutura da comunidade arbórea de igapó no Parque Nacional do Jaú, Amazônia Central

Abstract

Several studies have described the clear influence of the flood pulse in the differential distribution of species and the existence of different vegetation types along the topographic gradient in várzea floodplain. However, few similar studies were conducted in igapó floodplain, but the results obtained until now show that there is some variation in species composition according to flooding duration; but until now it has not been reported the existence of species zonation along the gradient. This study aimed to verify the influence of hydro-edaphic factors on the floristic composition, richness, diversity, basal area and density of individuals in igapó forest and identify the existence of species zonation over the flooding and edaphic gradients. For this, 10 plots of 1 ha were established in the igapó of the Jaú National Park. All palms and trees with DBH ≥ 10 cm were registered. Four soil samples per plot were collected, considering 16 soil variables for analysis. It was recorded 193 species, 115 genera and 41 families. The diversity obtained (Fisher α) was 39.34. The flooding duration was correlated to the variation of floristic composition, diversity and structure, except to density. The soil gradient was correlated to floristic composition, but not correlated to the diversity and structure. Only one species was virtually restricted to highly flooded sites, allowing the identification of a distinct vegetation type in these areas. The other species had differentiated concentration of abundance along the flooding gradient. There has been little structuring of the community according to the soil gradient, showing that soil variables are less important than flooding to the floristic composition in igapó.