Abstract
In the region of the Paraíba do Sul river valley in the State of São Paulo, Brazil, pasture areas have been replaced by eucalyptus plantations, which can modify the dynamics of water in the soils of the region. The objective of this work was to evaluate the behavior of water in a Red-Yellow Latosol in two vegetative coverings, a six-year-old eucalyptus plantation, and a native forest, in the process of regeneration which began twenty years ago. The study was developed in the Una River basin from June 2009 to April 2011. The soil water potential was measured by 96 sensors (Watermark ™) at the depths of 20, 60 and 120 cm. The Available Water Capacity (AWC) and weekly residual soil storage for each layer were calculated. It was observed that the three layers reacted to the processes of rainfall and evapotranspiration and that there was a difference between the storage of water in the soil in the eucalyptus and native forest areas. There was no water restriction in the studied period; however, the variations in native forest storage were smoother than the variations occurring for eucalyptus. In the mean of the whole period and for the three layers, the storage in the native forest and eucalyptus were 88% and 64% of Available Water Capacity (AWC = 183 mm), respectively. These results show the native forest water conservation capacity in watersheds.
Highlights
The region of the Paraíba Valley, in the State of São Paulo, has potential for expanding eucalyptus cultivation due to its climate and the availability of large areas occupied by degraded pastures
It is fundamental to analyze the behavior of water in the soil with eucalyptus cover and other vegetative cover, especially of native forest, since there is a great discussion in relation to water availability in watersheds with extensive areas planted with eucalyptus
The values determined for soil density, soil particle density and total porosity (p) in the native forest and eucalyptus areas for the different layers are presented in Table 1, where it is verified that both areas have similar characteristics in terms of these parameters
Summary
The region of the Paraíba Valley, in the State of São Paulo, has potential for expanding eucalyptus cultivation due to its climate and the availability of large areas occupied by degraded pastures. It is fundamental to analyze the behavior of water in the soil with eucalyptus cover and other vegetative cover, especially of native forest, since there is a great discussion in relation to water availability in watersheds with extensive areas planted with eucalyptus Another important aspect to consider in the water consumption of a region is the modification of the use and occupation of the soil by extension of one economic activity to the detriment of others. According to Carriello and Vicens (2011) silviculture developed over pasture areas (55%), secondary vegetation (15%), gallery forest (9%) and areas with exposed soil (7%)
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