tailieunhanh - Báo cáo lâm nghiệp: "Predicting the environmental thresholds for cambial and secondary vascular tissue development in stems of hybrid aspen"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:"Predicting the environmental thresholds for cambial and secondary vascular tissue development in stems of hybrid aspen" | Ann. For. Sci. 62 2005 565-573 INRA EDP Sciences 2005 DOI forest 2005049 565 Original article Predicting the environmental thresholds for cambial and secondary vascular tissue development in stems of hybrid aspen Peter W. BARLOWa Stephen J. POWERSb a School of Biological Sciences University of Bristol Woodland Road Bristol BS8 1UG UK b Biomathematics and Bioinformatics Division Bawden Building Rothamsted Research Harpenden Hertfordshire AL5 2JQ UK Received 19 May 2004 accepted 9 March 2005 Abstract - The interaction between environmental conditions and the developing secondary vascular tissue in young stems of hybrid aspen Populus tremula X P. tremuloides was studied with the aid of a differential equation regression model. Two data sets were combined. The first set consisted of the accumulated numbers of cells such as xylem fibres vessels phloem and parenchymatous ray cells in the radial cell files of stems sampled at intervals over a period of 16 months. Also counted were the numbers of fusiform cambial cells accumulated within the radial files and upon the cambial perimeter initial cells . The second data set pertained to the external environment and values were gathered at close time-intervals during the same stem-sampling period. The environmental variables were temperature and illuminance from the latter an estimate of day-length was made. These variables were used to construct developmental-time units values of which were regressed against the accumulated numbers of the various cell types in the secondary vascular tissues. Regression analyses led to estimates not only of rates of cell production but also to the basal threshold values of the environmental parameters above or below which the various cell productions were initiated or terminated in relation to seasonal conditions. In this way the critical conditions for the production of each of the various cell types could be identified. cambium developmental-time units hybrid aspen modelling secondary