For the second Italian forest inventory a three-phase sampling design for stratification was adopted. The first two phases allowed to estimated the forest area and its partition into inventory categories and forest types; the second phase field survey also made it possible to assess many important qualitative attributes, while quantitative measurements were curried out mainly in the third phase field survey. This sampling design is marked by a big flexibility since allows modulation of each sampling phase, depending on available financial resources and the required level of precision.

The Italian national forest inventory adopts a hierarchical system of classification, consistent with the FAO-Forest Resources Assessment (FRA 2000) forest definition (UN-ECE/FAO,1997) and with the first level of the CORINE Land Cover System (European Commission 1993). Forest type assignment is based on the prevailing species within each sample plot .