Seasonal variations in soil water in two woodland savannas of central Brazil with different fire history.
Seasonal variations in soil water in two woodland savannas of central Brazil with different fire history.
复制标题
DOI：
10.1093/treephys/28.3.405
复制
发表时间：
2008-03
期刊：
影响因子：
4
通讯作者：
C. Quesada;M. Hodnett;L. M. Breyer;Alexandre J.B. Santos;S. Andrade;H. Miranda;A. Miranda;J. Lloyd
中科院分区：
文献类型：
--
作者：
C. Quesada;M. Hodnett;L. M. Breyer;Alexandre J.B. Santos;S. Andrade;H. Miranda;A. Miranda;J. Lloyd
在两个塞拉多（狭义）地区的火灾历史和木本植被密度对比，确定土壤含水量的变化。该研究于1999年至2001年在巴西布拉西利亚附近进行。用中子探头在每个站点的三个接入管中测量土壤含水量，深度为4.7 m。其中一个地点已经防火30多年，因此木本植物密度很高。另一个地点经常被烧毁，草本植被密度高，木本植被较少。土壤水分吸收模式具有很强的季节性，尽管在水文过程的相似性，保护区系统地使用更多的水比烧毁的地区。三个暂时连续的吸水模式进行了区分，其特征在于从土壤深度的变化，水提取。在旱季初期，植被利用整个土壤剖面的水分，但对上层土壤的水分略有偏好。在旱季的高峰期，植被利用了地表1.7米以下的大部分或全部可用水，但继续从更深的地方取水。在第一次降雨后，所有用水都来自最近湿润的上层土壤。蒸发速率是土壤水分有效性的线性函数，表明大气水分需求和植被的生理响应有很强的耦合。
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.