Nutrient Accumulation and Cycling in Loblolly Pine (Pinus taeda L.) Plantation Ecosystems: The First Twenty Years1
- G. L. Switzer and
- L. E. Nelson2
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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