Published in Proceedings of the Eleventh Biennial Southern Silvicultural Research Conference, March 20, 2001, pages 38-41. This article is in the public domain. Published by the Pacific Southwest Research Station, USDA Forest Service.
Nitrogen and phosphorus use efficiency (NUE and PUE, respectively), the annual amount of stemwood produced per unit net N or P used in total aboveground production, were examined in 17-year-old pure stands of unthinned loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Englem.) planted at two spacings. Slash pine stands had a greater NUE and PUE than loblolly pine, which was attributed to greater relative allocation of aboveground production to stemwood, lower foliar N and P concentrations, and greater foliar retranslocation of N and P by slash pine. Compared to 2.4 x 2.4 meter spaced stands, denser 1.2 x 1.2m spaced stands had lower NUE and PUE, which may be related to a sustained drought. Results of this study imply that nutrient management should differ in stands of varying composition and structure.