tailieunhanh - Báo cáo lâm nghiệp: "Optimization of carbon gain in canopies of Mediterranean evergreen oaks "

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài: "Optimization of carbon gain in canopies of Mediterranean evergreen oaks. | Ann Sci For 1996 53 547-560 Elsevier INRA 547 Original article Optimization of carbon gain in canopies of Mediterranean evergreen oaks s Rambal1 c Damesin 1 R Joffre 1 M Méthy 1 D Lo Seen 2 Centre d ecologie fonctionnelle et evolutive CNRS BP 5051 34033 Montpellier cedex France 2 Jet Propulsion Laboratory NASA Pasadena CA 91109-8099 USA Received 8 December 1994 accepted 10 November 1995 Summary The main goal of this study was to analyze the depth-distribution of leaf mass per area LMA measured in ten canopies of Mediterranean evergreen oaks five canopies of Quercus coc-cifera and five canopies of o ilex across soil water availability gradients in southern France Spain and Portugal. There was a significant site effect on LMA with values being lower in mesic sites compared to those on xeric sites. In all canopies LMA decreased by up to 50 from the top to the bottom. The relationships between cumulative leaf area index and LMA could be represented by an exponential function. For two canopies of Q ilex growing in contrasting environments we analyzed the interrelationships among LMA mass-based nitrogen mass-based metabolic versus structural total fiber content photosynthetic electron transport and carbon isotope composition. There was no difference in massbased nitrogen or fiber content among upper and lower canopy positions in both locations. The maximum quantum yield of linear electron flow can be considered to be constant within the canopy. The area-based maximal electron transport rate and the carbon isotope composition were significantly linearly related to the LMA. Finally we tested whether the observed depth-distribution follows the pattern suggested by some optimization theories. Mediterranean evergreen canopy I leaf mass per area photosynthesis-related leaf property Quercus ilex Quercus coccifera Resume Optimisation du gain de carbone par les canopées de chênes méditerranéens à feuillage persistant. Le principal objectif de cette étude est d analyser la .

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