Volume function for the tree farming English oak plantations of the Valdarno (Tuscany, Italy)

In the past centuries, a notable reduction of lowland forests in Italy was detected as a result of the expansion of intensive agriculture and deforestation activities. According to the National Forest Inventory (INFC 2005), the English oak (Quercus robur L.) is mainly a scattered species distributed across 146,000 hectares of mixed forests. This species has been used in many national programs to recreate woods in the lowlands as well as tree in farming plantations. In the 1980s, within the restoration program of the Santa Barbara mining area in the Municipality of Cavriglia (Valdarno, Tuscany), about 172 hectares of tree farming plantations were created with English oak. Due to the shortage of specific volume equations for Italian plantations, a sampling campaign was carried out. The volume of 299 sample trees was measured using the Heyer formula and a volume equation was studied as a polynomial function of DBH and total height of trees. The final equation demonstrated to be quite robust with a RMSE of 0.0176 m3 corresponding to a relative RMSE of 10%.