The Seasonal Succession of Biotic Communities in Wetlands of the Tropical Wet‐and‐Dry Climatic Zone: II. The Aquatic Macrophyte Vegetation in the Pantanal of Mato Grosso, Brazil.

Abstract

AbstractThe seasonal succession of macrophyte communities on temporarily flooded wetlands in the Pantanal of Poconé was investigated by general surveys of the region and by semi‐quantitative surveys conducted on an area of 2500 m2 with a gradient of water depth steep enough to permit a correlation of the species diversity with the depth and duration of flooding. The tropical wet‐and‐dry climate is the main determinant of the regional ecological conditions, and the seasonal variations of the physical and chemical factors, including the alternation between aquatic and terrestrial conditions over most of the area, produce a pronounced seasonal succession. During all of the seasons, the occurrence and growth of the plant species on the area surveyed was found to be inversely correlated with the water depth, but the statistical significance of the findings varied during the course of the year. The plant species are discussed individually, since little or nothing had previously been reported about the autecology of several of them. In addition, a general survey is made of the common aquatic and wetland plant species encountered in the region. On sites temporarily inundated during the course of the year, there is usually a succession of vegetation involving purely terrestrial and aquatic species as well as short‐lived annuals that appear only during the transition period from wet to dry and perennials with seasonal periods of dormancy during periods of excessive dryness.