tailieunhanh - Báo cáo khoa học: "Water balance of a Southern Moravian floodplain forest under natural and modified soil water regimes and its ecological consequences"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Water balance of a Southern Moravian floodplain forest under natural and modified soil water regimes and its ecological consequences. | 15 Ann. For. Sci. 58 2001 15-29 INRA EDP Sciences 2001 Original article Water balance of a Southern Moravian floodplain forest under natural and modified soil water regimes and its ecological consequences Jan Cermák and Alois Prax Institute of Forest Ecology Mendel University of Agriculture and Forestry Zemedelska 3 61300 Brno Czech Republic Received 10 April 2000 accepted 20 June 2000 Abstract - Stand water balance was calculated in a floodplain forest in Southern Moravia. A model was applied to actual and theoretical scenarios of climate and soil water supply. Rooted and root-free soil volumes were considered separately because root development was poor for these trees. Input data . measured flows within the system including sap flow rate characterize both the period of regular natural floods and period when floods were interrupted for over 20 years because of canalization of rivers in the region. Under non-limiting underground water supply net precipitation supplied only about 50 and 25 of water for actual evapotranspiration Et under mild and dry weather respectively and the other 30 and 60 came from underground sources. The model also characterizes the theoretical situation of no underground water supply when Et may decrease significantly. An important limit for water supply to the trees may be the maximum hydraulic conductivity K allowing horizontal transport in heavy soils because a small decrease in soil water content 2 to 4 vol causes a large drop in K. K may become supply-limiting before soil water potential becomes a limiting factor. Trees with smaller or damaged root systems or lower root shoot ratio were especially threatened by drought even on relatively moist heavy soils. floodplain forest large trees root systems water balance soil hydraulic conductivity limiting water supply Southern Moravia modeling Résumé - Bilan hydrique d une forêt dans une plaine alluviale du Sud de la Moravie en conditions naturelles ou sous des regimes hydriques modifiés .

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