Abstract: The objective was to provide a pilot increment model for major species in the Caspian forests including Common Hornbeam (Carpinus betulus L.), Oriental Beech (Fagus orientalis Lipsky) and Heart Leaved Alder (Alnus cordata Desf.) by routinely measured variables in forest inventories. The only published and reliable data of an accomplished inventory in the western Caspian forests have been used to construct a database including all available explanatory variables of volume increment. Potential*reducer method was applied in this research to develop tree volume increment models. Volume increment models have been well-estimated for major species according to diameter at breast height (DBH), ecological aspects (ASP) and stand density (SD). Based on coefficient of determination, the models explained between 45 to 83% of volume increment variability. The results showed a descending ranking of volume increment from alder, hornbeam to beech for trees having DBH inferior to 70 cm. The average elasticity (E%) of volume increment to ASP indicated that hornbeam trees (0.85%) were approximately two times more sensitive than beech trees (0.46%) while no sensitivity was observed in alder trees. In the same way, hornbeam trees were appeared to be a bit more sensitive (0.41%) than alder (0.32%) to SD whereas no sensitivity was observed in beech trees. Although the presented increment models can be employed for applied purposes in the western Caspian region, model enhancement is expected if more detailed and larger dataset including soil, microclimate and forest structure data are incorporated.