Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:Predicting the yield of Douglas fir from site factors on better quality sites in Scotland. | Ann Sci For 1995 52 619-634 Elsevier INRA 619 Original article Predicting the yield of Douglas fir from site factors on better quality sites in Scotland AL Tyler1 DC Macmillan 1 J Dutch 2 Macaulay Land Use Research Institute Craigiebuckler Aberdeen AB9 2QJ 2 Forestry Authority Northern Research station Roslin Midlothian EH25 9SY UK Received 2 January 1994 accepted 14 June 1995 Summary In Scotland as a result of recent changes in agricultural policy and grant schemes there is now greater potential for planting a wider range of more productive forestry species on better quality land. In order to permit accurate production forecasting and financial appraisals for any such afforestation it is necessary to develop predictive yield models. This article describes the development of a multiple linear regression model for the prediction of General Yield Class GYC of Douglas fir using readily assessed or derived site factors. Climate surfaces developed by spatial analysis of weather data were used to predict temperature and rainfall for 87 sample sites to a resolution of 1 km2. Estimates of wind climate were derived from a regression model using geographic location elevation and topographic exposure. Multivariate analysis of these and other soil and topographic variables indicate that temperature and exposure are most important in determining the productivity of Douglas fir on better quality sites in Scotland. As crop age increases GYC declines and the possible reasons for this effect are discussed other factors are also discussed such as the genetic variability of Douglas fir and problems associated with establishment and form. Douglas fir I productivity I yield models I site factors I climate Resume Prédire la production du douglas à partir de facteurs stationnels sur des terrains de meilleure qualité en Écosse. Suite aux récents changements de politique agricole et de schemas d attribution des subventions il existe actuellement en Écosse de nouvelles possibilités pour .
