Biology and Management of White Spruce Seed Crops Reforestation in Subarctic Taiga Forests

Abstract

Seed production is the most dramatic event in the life cycle of trees and is the first step in forest regeneration. Embryos of white spruce are fragile during germination, and they depend on vigorous seeds for survival and growth. Mortality of white spruce seeds and seedlings is high in northern forests because climate and microhabitat are often unfavorable for seed germination and seedling establishment. Large quantities of high-quality seed are required for natural and artificial regeneration of white spruce forests at high latitudes. The first chapter of this bulletin describes the reproductive process of white spruce and factors that affect cone and seed production and seed quality. Knowledge of the reproduction cycle and factors that affect seed production and quality of white spruce is essential for forecasting and managing seed crops. Evidence that white spruce is a genetically variable species in northern forests is summarized in the second chapter. This chapter includes recommendations for maintaining the gene pool of natural populations and for seed transfer in afforesting sites that do not have endemic populations. A procedure for delineating planting zones for adapted seed sources is described as an alternative for provisional seed zones that only reduce the risk of maladaptation from long-range seed transfer . The final chapter outlines steps in harvesting white spruce seed crops and can be used as a working manual . Practical procedures are described for evaluating quality and quantity of white spruce seed crops , certifying the geographic origin of seed parents , collecting cones , and processing seeds to mainatin viability for many years. The genetic structure of white spruce and the environment-embryology relationships that effect seed production and maturation have not been studied in detail . The need for research in the areas of genetics, biochemistry, physiology, and ecology is discussed in each chapter. The results of such research will help to improve seed yields and make the management of white spruce crops more profitable in Alaska and Yukon.