Nitrogen fertilization effects on foliar nutrient dynamics and autumnal resorption in maidenhair tree (Gingko biloba L.)

We quantified seasonal foliar nutrient dynamics and autumnal N and P resorption of individuals of the deciduous gymnosperm Gingko biloba (maidenhair tree) growing in compacted, urban soils over two years following a single fertilization with 150 kg/ha/yr of N (and no P). Mean foliar nutrient concentrations were more similar to those reported for angiosperm trees than for other gymnosperms. During the autumn following fertilization, 46% and 48 of foliar N and P were resorbed, respectively; during the second year both increased significantly, to 68% of foliar N and 74% of foliar P. Absolute N resorption was also greater during the second year, whereas absolute P resorption did not differ significantly between years. During the second year, the level of N resorption rates was similar to that reported for Larix laricina (larch or tamarack), a needle‐leafed, deciduous gymnosperm, and greater than those reported for broad‐leafed deciduous angiosperms. The level of 1992 P resorption was similar to those reported for a wide range of gymnosperms and greater than those reported for most angiosperms. N fertilization allowed Gingko trees to maintain typical foliar N dynamics even during a persistent drought during which foliar P dynamics were significantly altered.