tailieunhanh - Báo cáo lâm nghiệp: "Reconstruction of crown length of Norway spruce (Picea abies (L.) Karst.) and Silver fir (Abies alba Mill.) – technique, establishment of sample methods and application in forest growth analysis Peter SPATHELF"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Reconstruction of crown length of Norway spruce (Picea abies (L.) Karst.) and Silver fir (Abies alba Mill.) – technique, establishment of sample methods and application in forest growth analysis Peter SPATHELF. | 833 Ann. For. Sci. 60 2003 833-842 INRA EDP Sciences 2004 DOI forest 2003078 Original article Reconstruction of crown length of Norway spruce Picea abies L. Karst. and Silver fir Abies alba Mill. - technique establishment of sample methods and application in forest growth analysis Peter Spathelf Forstdirektion Tubingen Im SchloB 72074 Tubingen Germany Received 22 April 2002 accepted 27 November 2002 Abstract - A technique to date branch mortality was used to estimate crown recession of Norway spruce and Silver fir in uneven-aged mixed forests on temporary plots of the Black Forest Germany . In a preliminary study accurate and efficient sampling methods were developed. Results of the main study indicate that unthinned trees show a high crown recession rate contrarily to thinned trees which reveal more balanced crowns. Height increment and Hegyi s competition index were the only significant variables left in the final regression model. Trees of equal competition status but with higher height increment exhibit higher crown recession rates. This tendency is even more pronounced with Norway spruce than with Silver fir. Norway spruce however shows a higher crown recession rate with increasing competition compared with Silver fir of similar height increment. This seems to indicate a lower shade tolerance of Norway spruce. Norway spruce Silver fir crown length crown recession branch mortality Résumé - Evolution en hauteur des houppiers d épicéa Picea abies L. Karst. et de sapin pectiné Abies alba Mill. - technique mise en leuvre de méthodes d échantillonnage application à l analyse de la croissance des forets. On a utilise une technique permettant de dater la mortalité des branches pour estimer la regression par le bas des houppiers de l epicea et du sapin pectiné dans des placettes temporaries installées dans des forets mélangées et inéquiennes de la Foret Noire Allemagne . Les résultats démontrent qu en l absence d eclaircie les arbres présentent un taux de .