Environmental Factors and Distribution of Tree Species in Wetlands Eastern Amazon, Brazil

Resumo

This article analyzes the influence of environmental factors and their correlations on the distribution of tree species, which is an efficient way to understand the differences in composition and richness between forest ecosystems. Although many works have traced an efficient profile in an attempt to describe the composition and species richness associated with environmental factors and the flooding regime throughout the Amazon, few have portrayed these relationships between tidal floodplain and igapo forests in the Amazon estuarine. We analyze the influence of environmental factors in soil (physical and chemical) and the flooding period on the distribution, composition and richness of tree species. The examined forests were systematically evaluated in 26 ha^-1, divided equally between them. All trees (DBH ≥ 10 cm) were recorded, and principal component analysis (PCA) was employed as a way of assessing the associations of environmental variables and species distribution. The environmental variables responded differently for each type of forest, showing some consistency with the peculiar characteristics of each environment; in the igapo forest, acidity, aluminum concentration, flood duration, potassium and sand content affected species distribution, while CEC, SB, silt, Ca, flood duration, pH, K, and P content did so in the floodplain. Notably, the forests presented similar structures. Nevertheless, the igapo forest presented three times more species richness than the floodplain. We suggest that the distribution of species responds to environmental factors in a very particular way, allowing each environment to establish greater efficiency in the use of its resources.

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