Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:" Vegetative development, primary and secondary growth of the shoot system of young Terminalia superba tropical trees, in a natural environment. I. Spatial variation. | 389 AnnSciFor 1992 49 389-402 Elsevier INRA Original article Vegetative development primary and secondary growth of the shoot system of young Terminalia superba tropical trees in a natural environment. I. Spatial variation in structure and size of axes E de Fay University de Nancy I Laboratoire de biologie des Ligneux BP 239 54506 Vandceuvre-lès-Nancy Cedex France Received 21 August 1991 accepted 17 April 1992 Summary Spatial variations in trunk structure including wood histology and size of axes were examined in 5 21-month-old Terminalia superba Engl and Diels trees grown in a natural tropical environment. Long and shorter internode series alternated along the main axes forming rather poorly delimited units of extension. In trunk wood the paratracheal axial parenchyma of the confluent type formed irregular bands the spacing of which varied gradually increasing and decreasing alternately. These widely- and narrowly- spaced parenchyma bands differentiated various wood layers. The radial enlargement and wall thickness of fibres also varied in the same manner as did but to a lesser extent the width of parenchymal bands the radial enlargement of parenchyma cells and vessels and the wall thickness of vessels. The number of various wood layers in trunk segments that were defined by variations in intemodal length was not related to the order of appearance of the trunk segments in question. These results suggest that trunk wood exhibited alternating dense and not very dense wood layers but they did not provide visible structural evidence of a well-pronounced growth periodicity in the main shoot of Terminalia superba. The existence of a structural discontinuity in the peripheral wood and the significance of the basipetal differentiation of the outermost adjacent wood layer have been discussed in relation to seasonal changes in climate and phenology. On the other hand trunk thickness increased markedly from 5 cm above to 5 cm beneath the upper pseudowhorls of branches. The .
