Adapting Scots pine Regeneration to the Changing Climate : An investigation of the effects of seed coating, arginine addition, and planting position

In Sweden, new forest stands have long been artificially regenerated using conifer seedlings. While standardized and widely adopted, this approach may need to be further adapted to the predicted increases in variations in the weather, such as extended periods of drought. In light of this, coated seeds of Scots pine, as well as adding arginine phosphate to the coating, were tested across 12 sites in Sweden. The coatings should facilitate germination and establishment of seedlings, while the addition of arginine phosphate would enhance growth. In another study across 11 sites in Sweden, the effects of arginine phosphate addition on survival and growth of nursery grown seedlings planted into mineral soil or in capped mounds were tested. Seedlings planted in mineral soil may be better adapted to dry conditions but may suffer from lower availability of nutrients compared to the capped mounds. The results showed no difference in survival between seedlings from coated seeds with or without arginine (following three growing seasons), whereas survival of nursery grown seedlings increased as a result of arginine addition (following two growing seasons). Arginine phosphate addition increased growth, both for coated seeds and for nursery grown seedlings planted in mineral soil as well as in capped mounds. The importance of precipitation was demonstrated in both studies, with positive relationships between survival and precipitation in the month following deployment. Hence, of the methods tested here, planting nursery grown seedlings in mineral soil with an amendment of arginine phosphate appears to be the most valuable to enhance both survival and growth of seedlings subjected to dry weather conditions