tailieunhanh - Báo cáo lâm nghiệp:"An examination of the interaction between climate, soil and leaf area index in a Quercus ilex ecosystem"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"An examination of the interaction between climate, soil and leaf area index in a Quercus ilex ecosystem" | 153 Ann. For. Sci. 60 2003 153-161 INRA EDP Sciences 2003 DOI forest 2003008 Original article An examination of the interaction between climate soil and leaf area index in a Quercus ilex ecosystem Corine Hoff and Serge Rambal DREAM Centre d Écologie Fonctionnelle et Évolutive FRE 2633 CNRS 34293 Montpellier Cedex 5 France Received 2 Avril 2002 accepted 19 August 2002 Abstract - In Mediterranean-type ecosystems water availability is one of the most significant variables that regulates whole plant leaf area. An equilibrium should exist between climate soil and leaf area in such water-limited conditions. The aim of this study was to identify the relations between leaf area index LAI environment climate soil and fluxes water carbon in Mediterranean evergreen oak Quercus ilex L. ecosystems. To achieve this objective 50-years simulations were performed using the FOREST-BGC model by varying LAI for a reference site and for different climates and soil water holding capacities SWC . Transpiration drought stress net photosynthesis and canopy water use efficiency WUE were examined on a yearly basis for the last ten years of the simulation. Similar to other findings our results show that LAI depends on site water availability including both climate precipitation potential evapotranspiration and soil factors . water storage capacity . Low SWC limit the development of the ecosystem. On high SWC soils development is mainly limited by the climate. When LAI increases under constant SWC and climate conditions the decrease in annual transpiration per unit of LAI is accompanied by an increase in drought stress. Equilibrium LAI maximizes carbon assimilation. For the reference site the equilibrium LAI is close to the observed value . The corresponding transpiration assimilation and WUE are 375 mm 1251 g C m-2 and mmol CO2 mol-1 H2O respectively. For the different sites there is an hyperbolic decline of WUE with increasing SWC. This implies that production efficiency .