COMPARING NATURAL AND PLANTED BLACK SPRUCE SEEDLINGS .2. NUTRIENT-UPTAKE AND EFFICIENCY OF USE

The acclimation of planted black spruce (Picea mariana (Mill.) B.S.P.) seedlings to site nutrient condition was assessed by comparing their nutrient status with that of naturally regenerated seedlings on the sa me site during a 2-year period. The seasonal patterns for N, P, and K status (nutrient concentration and content) were markedly different fo r planted and natural seedlings. The former showed an early season dec line in concentration that was less evident or absent in natural seedl ings. This pattern persisted 1 year after planting, although biomass a ccumulation increased. Nutrient ratios indicated a strong culture regi me effect on the balance of nutrients. This effect was considerably di luted 1 year after transplantation. Phosphorus and K levels in 1-year transplants and natural seedlings were close to the defined optimums f or black spruce. Nutrient use efficiency of planted seedlings tended t o increase with acclimation to site. Retranslocation from older needle s of planted seedlings indicated net export of nutrients, while natura l seedlings had a storage capacity in older foliage, indicated by net nutrient accumulation at the end of the growing season. Planting signi ficantly reduced biomass allocation to current foliage, and naturally regenerated seedlings produced current foliage earlier in the growing season compared to planted seedlings.