Effect of vegetation and seasons on the water content of soil climatic conditions of the Atlantic Forest in Southern Brazil

Abstract

The objetive of this work was monitoring of the soil water content behavior, for grass native field and native forest vegetation cover, in an area characteristic of Atlantic Forest in Southern Brazil. To obtain the soil water content, some electronics tensiometers with pressure transducer were utilized and were placed 0.10, 0.30 and 0.70 m below the soil surface, from October 2010 to May 2011. The values of matric potential, measured by tensiometers, were transformed into soil water content values based on a soil water retention curve for each depth. The obtained results showed that in native fields and native forests, the greatest variations of tension, water content, and water storage in the soil happened at a depth of 0.10 and 0.30 m. At a depth of 0.70 m these variables presented less variations, mainly in native field soil cover. The soil water content was greater in the forested land cover than in the native field. Different seasons throughout the year directly influenced the behavior of analyzed variables. In the summer, the values of soil water tension observed in the forested land cover were higher than those observed in the native field. In the winter season, there was a change in that behavior at depths of 0.30 and 0.70 m and the values of soil water tension became smaller than the forested land cover. Great variations in the soil water tension were observed from October to April (summer), and became steady after May (in the beginning of winter). In the grass native field, most of the time, the greatest soil water content was observed at a depth of 0.10 m followed by depths of 0.70 and 0.30 m, respectively. During dry periods, the greatest soil water content was observed at a depth of 0.70 m, followed by depths of 0.10 and 0.30 m, respectively. In the forest, except for rainy periods, the greatest content of the soil water occurred at a depth of 0.70 m. For the conditions of this study, the total storage of water in the soil was 31.05% greater in the native forest than in the native field.