Efeitos da inundação sobre o solo e vegetação com dominância de Vochysia divergens Pohl (Vochysiaceae) no Pantanal Mato-Grossense

Abstract

The objective of this research was to understand effects of flooding on soil and vegetation with dominance of Vochysia divergens Pohl (Vochysiaceae) in Pantanal, Mato Grosso. The study area is located in Poconé / MT. It was established five transects of 50 meters each with sampling points at intervals of 5 meters. A meteorological station was installed at 2 km to the South of the seasonally flooded forest to measure daily temperature and air humidity and rainfall. The variables analyzed were: surface water depth, humidity and soil properties; density, basal area, frequency, importance value and diversity of plant species; litter production; and increment in diameter of V. divergens. Analysis of Covariance, Simple Linear Regression, Shapiro-Wilk test and Spearman Correlation were used to statistical analyzes in the program R. The local microclimate showed similar seasonality to the regional climate. The chemical properties of the soil changed after the flood and soil became more acid. A gradient with dominance of V. divergens occurred in the study area. Plant density decreased with increasing in stem diameter. Frequency distribution of diameter classes revealed that the plant community is young and V. divergens population is in transition from young to old trees. The density and relative cover index of V. divergens decreased as the water depth and flood duration increased, respectively. Plant diversity decreased with increasing of V. divergens density. The annual increment in diameter of V. divergens was 4.89 mm. This increment showed seasonal dynamics with higher values from January to March (flooding period with rainfall), absence or negative increment from July to September (dry season and reproductive period), and intermediate values from April to June and from October to December (transitional period between the dry and wet season). The increment followed the patterns of regional climate and phenological changes of species.