A. J. B. Santos

SEASONAL AND DEPTH VARIATION OF SOIL MOISTURE IN A BURNED OPEN SAVANNA (CAMPO SUJO) IN CENTRAL BRAZIL

The soil water regimes of two areas of open savanna (campo sujo) near Brasilia, Brazil, were monitored between August 1999 and November 2000. Each area was subjected to a different fire regime. Soil water content was measured to a depth of 3.6 m, using a neutron probe. The profile storage at the end of the 1999 and 2000 dry seasons was very similar despite a difference in dry season duration and large differences in rainfall in the preceding wet seasons, indicating that the vegetation is conservative in its water use. In the last two months of the dry season, the water content of the upper 0.6 m of the soil profile did not decrease further, suggesting that the vegetation had used all of the available water in this layer. The seasonal variation in soil water storage to a depth of 3.6 m was 403 mm, 65% of which occurred below 1 m. The wet and dry season evaporation rates were estimated to be 2.4 mm/d and 1.6 mm/d, respectively, but for a month after fire, before regrowth started, the evaporation rate was less than 0.5 mm/d.