Cone crop fluctuations in Scots pine and Norway spruce

Abstract

The present work reports on comparisons (figs. 3 and 5) between observations of the annual cone setting of Scots pine and Norway spruce in various parts of the country carried out by the State rangers (table 2) and observations made by the National Forest Survey (table 1). On the basis of these comparisons the long series of State ranger observations (1909-1953) has been regionally transformed to an absolute scale of values (table 3). Calculations have been made by means of these series with the purpose of elucidating how often a certain level of cone setting occurs in various parts of the country (fig. 6) and what range of variation that might occur in respect of number of years between cone crops of a size considered worthwhile to collect (table 4).