Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Responses to elevated atmospheric CO concentration 2 and nitrogen supply of Quercus ilex L. seedlings from a coppice stand growing at a natural CO 2 spring. | 549 Ann. For. Sci. 56 1999 549-561 Inra Elsevier Paris Original article Responses to elevated atmospheric CO2 concentration and nitrogen supply of Quercus ilex L. seedlings from a coppice stand growing at a natural CO2 spring Roberto Tognetti Jon D. Johnson School of Forest Resources and Conservation University of Florida 326 Newins-Ziegler Hall Gainesville FL 2611 USA Received 15 September 1998 accepted 1 March 1999 Abstract - Quercus ilex acorns were collected from a population of trees with a lifetime exposure to elevated atmospheric CO2 concentration CO2 and after germination seedlings were exposed at two CO2 370 or 520 pmol mol-1 in combination with two soil N treatments 20 and 90 Limol mol-1 total N in open-top chambers for 6 months. Increasing CO2 stimulated photosynthesis and leaf dark respiration regardless of N treatment. The increase in photosynthesis and leaf dark respiration was associated with a moderate reduction in stomatai conductance resulting in enhanced instantaneous transpiration efficiency in leaves of seedlings in CO2-enriched air. Elevated CO2 increased biomass production only in the high-N treatment. Fine root foliage mass ratio decreased with high-N treatment and increased with CO2 enrichment. There was evidence of a preferential shift of biomass to below-ground tissue at a low level of nutrient addition. Specific leaf area SLA and leaf area ratio LAR decreased significantly in leaves of seedlings grown in elevated CO2 irrespective of N treatment. Leaf N concentration decreased significantly in elevated CO2 irrespective of N treatment. As a result of patterns of N and carbon concentrations C N ratio generally increased with elevated CO2 treatment and decreased with high nutrient supply. Afternoon starch concentrations in leaves did not increase significantly with increasing CO2 as was the case for morning starch concentrations at low-N supply. Starch concentrations in leaves stem and roots increased with elevated CO2 and decreased with .
