| Mature red spruce forests have declined in eastern Canada and the United States of America as a result of atmospheric pollution, acid deposition and deforestation. With the recent abandonment of agricultural fields, the opportunity has risen to evaluate the potential for red spruce forests to regenerate on these lands. The pattern and rate of red spruce regeneration will depend on the ability of the trees to disperse their seeds and on the ability of the seeds to grow in the new site. Soil humidity, temperature and nutrient availability, as well as light availability at the growing site will influence establishment success. In addition, the ability of red spruce seedlings to compete with the already established vegetation will affect their success.;Prince Edward Island National Park, which has a diverse land use history, is now an ecological island bordered by agricultural land to the south and by the Gulf of St. Lawrence to the north. Although there are doubts that red spruce could naturally regenerate onto the old fields because of a lack of propagules, no one has ever tested this hypothesis. The overall objective of my project was to examine the dispersal and potential for establishment of red spruce in young and mature forests and in adjacent old fields in Prince Edward Island National Park. My specific objectives were (1) to survey the vegetation present along transects from the forest interior out into adjacent fields; (2) to evaluate the abundance of the red spruce seed bank and seed rain; and (3) to test seed viability in forest and field soils from the study sites and under various light, humidity and temperature conditions. My hypotheses were: (1) because red spruce seeds are viable for only one year, there would be no red spruce seed bank and the seed rain would be the only source from which red spruce could naturally regenerate in the study sites, (2) because red spruce habitat is typically humid and shaded and because its wind-dispersed seeds should fall close to the parent trees, the regeneration rate would be higher inside the forest and diminish with distance into the field, and (3) because red spruce can grow in many soil types but its seedlings are particularly sensitive to drought, soil humidity would be the variable most affecting red spruce seed germination.;Results show that the studied old fields are already beginning to naturally reforest with red spruce saplings. On the other hand, none of the forest ground flora has invaded the fields. With only 39 red spruce seeds collected in the seed bank (N = 160 samples of 80 ml of soil), most of which were already decaying, the seed rain is the only source from which red spruce can naturally reforest the old fields. Red spruce seed rain was more abundant, particularly in the forest. From the germination tests, we inferred a germination rate of 0.004%; therefore, we could not test the effects of different soils and environmental conditions on red spruce seed germination. Red spruce will regenerate more slowly in the fields we studied than has been observed after forest harvests with little soil disturbance. Continual monitoring in our sites will be needed to determine whether additional red spruce trees should be planted. My project contributes to the Prince Edward Island National Park's understanding of the potential and mechanisms for red spruce regeneration in their old fields. This study fits within the research framework of maintaining and restoring the ecological integrity of national parks.;Key words: Picea rubens, regeneration, old field, seed bank, seed rain... |
