Chestnut high forest stands. biometrical study in the North of Portugal

Where site conditions are appropriate, Castanea sativa Mill. is a very suitable species for sub-mediterranical regions (Guerreiro, 1957). It is precisely in the north of Portugal mainly in Tras-os-Montes and Beiras where Castanea sativa is more representative. Over the last decade many new stands were installed under the European Community policies supporting forest investment. The main purpose for these young plantations is to produce high quality wood. Logs with medium and large dimensions can attain interesting profitability levels (125 €/m3 over bark in trees with diameter at breast height (d) over 30 cm). Taking into account the economical value of Castanea sativa and its increasing area expansion, without neglecting environmental and social values, it becomes important to follow sound silvicultural prescriptions and management practices which depend, among others, on the accurate estimation of wood contents through volume determination. In this study, regression analysis theory was used to obtain volume equations as a function of standing tree easily measured variables and also for modelling the relationship of tree total height (h) to diameter at breast height (d). A methodology was adopted to obtain models with the lowest possible bias in its volume estimates and, at the same time, with low correlation among regressors. Selected models, which are presented, can be used to construct volume tables, very useful tools for forest producers, namely small farmers in such a way that, as much as possible, avoid revenue losses Comparisons were made with equations used by the Forest Services