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Root functioning, tree water use and hydraulic redistribution in Quercus suber trees: A modeling approach based on root sap flow

David, Teresa S. ; Pinto, Clara A. ; Nadezhdina, Nadezhda ; Kurz-Besson, Cathy ; Henriques, Manuel O. ; Quilhó, Teresa ; Cermak, Jan ; Chaves, M. Manuela ; Pereira, João S. ; David, Jorge S.

Forest ecology and management, 2013-11, Vol.307, p.136-146 [Periódico revisado por pares]

Kidlington: Elsevier B.V

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  • Título:
    Root functioning, tree water use and hydraulic redistribution in Quercus suber trees: A modeling approach based on root sap flow
  • Autor: David, Teresa S. ; Pinto, Clara A. ; Nadezhdina, Nadezhda ; Kurz-Besson, Cathy ; Henriques, Manuel O. ; Quilhó, Teresa ; Cermak, Jan ; Chaves, M. Manuela ; Pereira, João S. ; David, Jorge S.
  • Assuntos: Agronomy. Soil science and plant productions ; Animal and plant ecology ; Animal, plant and microbial ecology ; Biological and medical sciences ; Drought ; Forestry ; Fundamental and applied biological sciences. Psychology ; Groundwater ; Physical properties ; Physics, chemistry, biochemistry and biology of agricultural and forest soils ; Soil science ; Soil water ; Stable isotopes ; Synecology ; Terrestrial ecosystems ; Water and solute dynamics ; Xylem anatomy
  • É parte de: Forest ecology and management, 2013-11, Vol.307, p.136-146
  • Descrição: •Q. suber showed a dimorphic root system with deep roots reaching groundwater.•Superficial roots are linked to sinker roots.•Stem sap flow was modeled from root sap flow with a high efficiency.•Trees used soil water and performed hydraulic descent during most of the year.•Trees used groundwater and performed hydraulic lift during the dry summer. Mediterranean evergreen oaks have to survive a long summer drought. Roots may play a relevant role under these conditions. We studied their structure and function in a mature Quercus suber L. tree in central Portugal. The root system was mapped till the lowest water table level (4.5m depth). Xylem anatomy was analyzed in a vertical profile belowground. Sap flow was continuously monitored for 1.5yrs in the stem and roots of this intensively studied tree (heat field deformation method) and in the stem of four trees (Granier method), in relation to environmental variables and predawn leaf water potential. The sources of water uptake were assessed by stable isotope analyses in summer. Results showed a dimorphic root system with a network of superficial roots linked to sinker roots, and a taproot diverting into tangles of deep fine roots submerged for long periods, with parenchyma aerenchyma. Transpiration was not restricted in summer due to root access to groundwater. The isotopic δ18O signature of twig xylem water was similar to that of groundwater in the dry season. Two functional types of superficial roots were identified: shallow connected and deep connected roots. A modeling approach was built considering that each superficial root was linked to a sinker, with part of the root deep connected (between the stem and the sinker) and part shallow connected (between the sinker and topsoil). This conceptual framework simulated tree stem sap flow from root sap flow with a high efficiency (R2=0.85) in four plot trees. On an annual basis, soil water and groundwater contributions were 69.5% and 30.5% of stem flow, respectively. Annual hydraulic lift and hydraulic descent were 0.9% and 37.0% of stem flow, respectively. The trees maximize the exploitation of the environmental resources by using the topsoil water during most of the year, and groundwater together with hydraulic lift (nutrient supply) in the dry summer. This study shows that a dimorphic root system, with roots reaching groundwater, is an efficient strategy of Q. suber trees to cope with seasonal drought. Knowledge of the functional behavior of Q. suber trees under shallow water table conditions may contribute to the definition of better adapted management practices and to anticipate their responses to climate change.
  • Editor: Kidlington: Elsevier B.V
  • Idioma: Inglês
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