Does the Age of Pinus sylvestris Mother Trees Influence Reproductive Capacity and Offspring Seedling Survival?

Abstract

We assess how the age of Pinus sylvestris mother trees influences seed size, seed viability, germination capacity and later offspring seedling survival under greenhouse conditions. Thirty trees ranging from 30 to 219 years old were selected in the north facing slopes in the Sierra de Guadarrama, where we could find the oldest Pinus sylvestris trees in central Spain. Forty cones per tree were harvested to study cone and seed characteristics (size and weight), seed viability and germination capacity related to the mother tree age. In addition, 25 germinated seeds per tree were grown in a greenhouse to assess offspring seedling survival during a death trial, where watering was stopped. Significant differences between trees in cone and seed morphological traits were observed. The age of the mother tree had a significant effect on cone size, seed size, and seed weight, but there was no effect on seed germination capacity and seed viability. Seedling survival was mainly affected by the decrease in water availability. However, a significant effect of the tree age was found once soil moisture had reached 0%. Our results show the ability of overmature Pinus sylvestris trees to maintain a relatively high reproductive capacity that assures its persistence.