© 1992 Heron Publishing—Victoria, Canada
Nutrient dynamics in singleleaf pinyon (Pinus monophylla Torr & Frem.) needles
R. L. Everett and D. F. Thran
Forestry Sciences Laboratory, 1133 N Western Avenue, Wenatchee, WA 89501, USA / Received January 22, 1991
Summary
Nutrient retranslocation from existing foliage of singleleaf pinyon pine (Pinus monophylla Torr. & Frem.) did not meet the nutrient demands of new needles on the same branch. Singleleaf pinyon pines, with an average
age of 177 years, located at an elevation of 2300 m on a ridge in The Sweetwater Range in Nevada, USA retained needles for
18 or more years and increased needle number per branch by 17–18% annually. With age, needles gained weight and accumulated
Ca, Mg, Fe, Zn, P, and Mn. The amount of N per needle showed no consistent trend with needle age. Only Cu and K declined in
concentrations and amounts with needle age and these differences were not statistically significant. Retranslocation of nutrients
at needle abscission could provide only 2 to 13% of the N, P, K, Fe, Cu, and Mg required by new needles. We conclude that
nutrient capital in existing foliage constitutes a long-term nutrient reserve for the tree rather than a mobile nutrient pool.
