A data system and a method for determining the harvestability and transportability of a stand marked for cutting, the method comprising: maintaining data on the properties of the soil of the stand; determining a value for the harvestability and transportability of the stand, which value is dependent on said properties; defining said value also on the basis of such conditions of said stand which affects said properties; maintaining data on the harvestability and transportability defined for the stand. Said property is one or more of the following: soil type, auxiliary attributes of the soil type, other permanent factors. Said conditions are one or more of the following: snow depth, frost depth, soil moisture content, temperature, amount of rainfall, quantity of growing stock, relations between tree species, other variable factors.