Productivity of boreal forests in relation to climate and vegetation zones

Many properties of forest stands in the boreal main zone have means that are specific to each boreal zone (i.e. subzones of the main climatic zone). These properties are arranged in zonal systems, called forest vegetational zones. The paper examines the vegetative productivity using three climatic variables: the effective temperature sum, the duration of the vegetation period, and the maximum soil frost penetration; each of them means for the period 1961–2000. Soil frost penetration was calculated mainly as a function of snow depth and frost sum. The productivity for each boundary between the boreal forest vegetational zones in Finland was obtained mainly from Ilvessalo, beginning with the boundary between the hemiboreal and southern boreal zones in the south and ending at the boundary between the middle and northern boreal zones in the north. The regional distribution of residuals reflects the regional variation of the soil fertility. A hypothesis that each boundary corresponds to a certain productivity from the western coast of Norway to western Siberia, was tested. The productivity for the boundary between the hemiboreal and temperate zones was found to be in accordance for the limit determined by vegetation. Some applications of the results are presented.