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Abstract

This paper analyses the relationship between the distribution of tropical floodplain vegetation and environmental factors such as the soil types, their physical-chemical properties and inundation dynamics in the northern Pantanal of Mato Grosso, Brazil. Fifty-four soil profiles of the four principal geomorphologic units of the lowland were classified into twenty-one units of the FAO-UNESCO system and related to eight vegetation formations. Under the deciduous and semideciduous woodland and forest formations on flood free riverbanks and relict dunes Arenosols, Solonetz and Alisols dominate. Inundation forests grow on a large variety of soil groupings such as Alisols, Solonetz, Fluvisols, Gleysols and Cambisols, mainly on fluvial deposits. Under the grassland formations of periodically flooded spreadings and depressions Planosols, Acrisols, Alisols, Fluvisols, Arenosols and Cambisols were cored, while Gleysols are common on swamps bearing Thalia geniculata or Cyperus giganteus. Canonical Correspondence Analysis was applied to study the influence of monitored environmental factors on spatial distribution of vegetation formations. Water regime and soil texture were found to define the grassland-forest boundaries as well as the transition between different grassland formations and between seasonal as well as evergreen forests