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Nutrient Accumulation and Cycling in Loblolly Pine (Pinus taeda L.) Plantation Ecosystems: The First Twenty Years
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1972
Year
Nutrient AccumulationBiogeochemistryBiogeochemical CyclesLoblolly PineNutrient BudgetEngineeringTotal Nutrient FundBiogeochemical CycleNutrient CyclePlantation EcosystemsNutrient StoichiometryForest ProductivityBiogeochemical ProcessForest SoilInitial Nutrient FundForest BiologyEarth ScienceSoil Biogeochemical Cycling
Over 20 years the loblolly pine plantation’s biomass increased tenfold and nutrient stocks of N, P, K, Ca, Mg, and S rose 4–11 times, reflecting their disposition and mobility. The study develops a nutrient‑budget accounting technique and proposes a biochemical cycle describing internal nutrient translocations within trees. The method calculates nutrient budgets by tracking inputs, outputs, and internal transfers among living and non‑living components. At 20 years, above‑ground nutrient stocks varied 12‑fold (298 kg ha⁻¹ N to 24 kg ha⁻¹ S), only 7–28 % of the total nutrient fund cycled annually, yet a substantial portion of annual needs is met by internal transfers, supporting a more realistic nutrient‑cycling model.
Abstract The mass of the system increased by 10‐fold during this period; and in terms of the system's initial nutrient fund, the quantities of N, P, K, Ca, Mg, and S increased approximately 4, 4, 11, 7, 5, and 3 times, respectively. The quantity of nutrients present in the above ground portion of the system at 20 years ranges from 298 for N to 24 kg/ha for S, about a 12‐fold difference. The portion of the system's total nutrient fund that is cycling to meet the annual requirement during the 20th year is small, ranging from a minimum of 7% for Ca to a maximum of 28% for K. This range is principally a reflection of the disposition and mobility of the nutrients. A technique of accounting for the system's nutrient budget is developed and an example presented. This technique indicates that, with some nutrients in these perennial systems, a sizable portion of the annual requirements is met by transfer within the living fraction of the system. Thus, in addition to the geochemical and biogeochemical cycles, a biochemical cycle is proposed which encompasses the internal transfer relationships or translocations of nutrients within the trees. Consideration of this phenomena leads to a more realistic concept of nutrient cycling within these and similar systems.