Association of western white pine cone crops with weather variables

Abstract

Twenty-one-year records of western white pine cone counts were analyzed with seven meteorological variables to find if any combinations of available weather factors were associated with the induction of reproductive buds and successful development of the strobili. The weather in three periods before the physical initiation of the potentially reproductive cycle showed association with cone counts: (1) sunny weather in June, 39 months before cone maturation; (2) warm, sunny, dry weather in September and October, 36 and 35 months before cone maturation; and (3) warm, sunny, dry weather with wide daily temperature range in June and July, 27 and 26 months before cone maturation, appeared to promote differentiation of potentially reproductive buds. During and after the initiation of bud primordia, the weather in four periods appeared to be associated with cone production: (1) warm and possibly wet weather in August, September, and October, 25 to 23 months before cone maturation; (2) rain in the third quarter of July, 4 weeks after pollination and 14 months before cone maturation; (3) warm temperatures in September, October, and November, 12 to 10 months before cone maturation; and (4) sunny, warm, dry weather in May, 4 months before cone maturation, appeared to be beneficial to cone development.