Journal Article

Seasonal variations in soil water in two woodland savannas of central Brazil with different fire histories

Carlos Alberto Quesada, Martin G. Hodnett, Lacê M. Breyer, Alexandre J.B. Santos, Sérgio Andrade, Heloisa S. Miranda, Antonio Carlos Miranda and Jon Lloyd

in Tree Physiology

Volume 28, issue 3, pages 405-415
Published in print March 2008 | ISSN: 0829-318X
Published online March 2008 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/28.3.405
Seasonal variations in soil water in two woodland savannas of central Brazil with different fire histories

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Changes in soil water content were determined in two cerrado (sensu stricto) areas with contrasting fire history and woody vegetation density. The study was undertaken near Brasília, Brazil, from 1999 to 2001. Soil water content was measured with a neutron probe in three access tubes per site to a depth of 4.7 m. One site has been protected from fire for more than 30 years and, as a consequence, has a high density of woody plants. The other site had been frequently burned, and has a high herbaceous vegetation density and less woody vegetation. Soil water uptake patterns were strongly seasonal, and despite similarities in hydrological processes, the protected area systematically used more water than the burned area. Three temporarily contiguous patterns of water absorption were differentiated, characterized by variation in the soil depth from which water was extracted. In the early dry season, vegetation used water from throughout the soil profile but with a slight preference for water in the upper soil layers. Toward the peak of the dry season, vegetation had used most or all available water from the surface to a depth of 1.7 m, but continued to extract water from greater depths. Following the first rains, all water used was from the recently wetted upper soil layers only. Evaporation rates were a linear function of soil water availability, indicating a strong coupling of atmospheric water demand and the physiological response of the vegetation.

Keywords: cerrado; evaporation

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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