tailieunhanh - Báo cáo khoa học: "Climatic signals in earlywood, latewood and total ring width of Corsican pine from western France"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Climatic signals in earlywood, latewood and total ring width of Corsican pine from western France. | 155 Ann. For. Sci. 57 2000 155-164 INRA EDP Sciences Original article Climatic signals in earlywood latewood and total ring width of Corsican pine from western France Franẹois Lebourgeois Laboratoire Ecosystèmes Forestiers et Dynamique du Paysage Engref 14 rue Girardet 54042 Nancy Cedex France Received 19 March 1999 accepted 15 November 1999 Abstract - The influence of climatic factors on the growth of Corsican pine growing at low elevation on acidic well-drained soils in western France was evaluated by comparing annual earlywood latewood and total ring indices with monthly temperature and precipitation data collected at Angers over the period 1922-1991. Latewood formation appeared to be more sensitive to climate than earlywood formation. Pointer years analysis and climatic models showed that summer drought was a major limiting-growth factor in the studied area. Extreme growth reductions specially highlighted the effects of low precipitation whereas response functions clearly underlined the importance of temperature. The climatic models accounted for 46 37 and 42 of the variability of total ring earlywood and latewood indices and suggested that the period of earlywood formation occurred mainly in early spring May whereas the growth of the latewood band was maximum in summer July . Winter photosynthesis and the advance in the timing of the resumption of cambial activity were possible causes of the positive winter temperature correlation with earlywood. A cool and wet spring was also beneficial to growth as it affected the water balance of the trees at the beginning of the growing season. Prior October weather conditions also influenced growth suggesting a preconditioning of the current year s growth by climate during the previous year. The regional climatic data revealed no change in precipitation and thermal amplitude between 1950-1997 a significant a increase in mean annual temperature of C mean annual minimum temperature C mean summer July-August .