tailieunhanh - Báo cáo lâm nghiệp:" Needle longevity, shoot growth and branching frequency in relation to site fertility and within-canopy light conditions in Pinus sylvestris"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:" Needle longevity, shoot growth and branching frequency in relation to site fertility and within-canopy light conditions in Pinus sylvestris" | Ann. For. Sci. 60 2003 195-208 195 INRA EDP Sciences 2003 DOI forest 2003012 Original article Needle longevity shoot growth and branching frequency in relation to site fertility and within-canopy light conditions in Pinus sylvestris Ulo Niinemetsa and Aljona Lukjanovab a Department of Plant Physiology Institute of Molecular and Cell Biology University of Tartu Riia 23 51011 Tartu Estonia b Department of Ecophysiology Institute of Ecology Tallinn University of Educational Sciences Kevade 2 Tallinn 10137 Estonia Received 10 September 2001 accepted 25 June 2002 Abstract - Changes in needle morphology average needle age shoot length growth and branching frequency in response to seasonal average integrated quantum flux density 2int were investigated in Pinus sylvestris L. in a fertile site old-field and an infertile site raised bog . In the fertile site the trees were 30 years old with a dominant height of 17-21 m and with average SD nitrogen content of dry mass of in the current-year needles. In the infertile site 50 to 100-yr-old trees were 1-2 m tall and needle N content was . Relationships between the variables were studied using linear correlation and regression analyses. With increasing irradiance shoot length L and shoot bifurcation ratio Rb the number of current-year shoots per number of shoots formed in the previous year increased in the fertile site but not in the infertile site. Despite greater branching frequency apical control was enhanced at higher irradiance in the fertile site. The shoot length distributions became more peaked positive kurtosis and biased towards lower values of Ls positive skewness with increasing Qint in this stand. The shoot distributions were essentially normal in the infertile site. Large values of Rb combined with the skewed distributions of shoot length resulted in conical crowns in the fertile site. In contrast lower bifurcation ratio normal shoot length distributions and low rates of shoot length .

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