Relationships between nutrient supply, nitrogen partitioning and growth in young Sitka spruce (Picea sitchensis)

摘要: Budget studies have shown that internal cycling may contribute a large proportion of the annual nutrient supply required to support new growth in trees. Use budgets quantify only quantifies net transfer nutrients within plant. Differential partitioning remobilized and current uptake could lead errors interpretation results from these studies. We quantified dynamic relationships among tree growth, by labeling N trees received contrasting amounts nutrient. Two-year-old seedlings Sitka spruce (Picea sitchensis (Bong.) Carr.) were grown sand culture greenhouse for one year. The balanced solution at either high (high-RAR) or low (low-RAR) relative addition rate throughout experiment. Current was labeled with (15)N April 13 July 25. Thereafter, re-potted clean unlabeled applied until November 13. Overall sustained approximately 10 weeks before treatment effects observed. Initially, no differences partition occurred, although favored roots plants low-RAR treatment. After 6 weeks, both altered favor Nutrient had effect on amount remobilization. No evidence found suggest taken up season partitioned preexisting shoots is late shoots. However, some high-RAR exhibited second flush later partially remobilization formed earlier season. demonstrated differential N. highlight limitations simple budget quantifying cycling.