XVI International Botanical Congess

We compared seasonal soil water content up to 8 m and estimated plant available water (PAW) and evapotranspiration (ET) of 2 adjacent savannas with contrasting tree densities in Brasilia. PAW in the tree-dominated community ranged from 216 mm in the dry season to 708 mm in the wet season. In the grass-dominated community it ranged from 71 mm to 402 mm, respectively. ET between the 2 communities ranged from 1.4 - 2.9 mm/day in the dry season and from 1.2 - 4.8 mm/day in the wet season. Deep-rooted plants used deep soil water during the dry season: 70% of the water used by the tree-dominated community came from 2 to 8 m and 50% used by the grass-dominated community came from 2 to 5 m. Differences between communities are due to root distribution in the soil profile and canopy seasonality