FOLIAR NUTRIENT DYNAMICS AND RESORPTION IN NATURALIZED LONICERA-MAACKII (CAPRIFOLIACEAE) POPULATIONS IN OHIO, USA

Foliar phosphorus (P) and nitrogen (N) concentrations and nutrient res orption in the forest understory shrub Lonicera maackii (Rupr.) Maxim (Caprifoliaceae) were measured along contiguous topographic gradients in two southwestern Ohio forests during 1992-1994. Mean summer foliar P varied significantly among topographic positions (but not sites or y ears), with uplands having greatest P concentrations and bottomlands e xhibiting the lowest. Unlike for P, the mean summer foliar N concentra tions varied little among sites, topographic positions, and years. Mea n absolute and proportional P resorption ranged from 0.48 mg/dm(2) (33 .7%) in slope positions to 0.80 mg/dm(2) (53.1%) in bottomland positio ns. Repeated-measures analysis of variance (RMANOVA) for P resorption indicated significant topographic and year effects, a site x year and a site x year x topographic interaction. Mean absolute and proportiona l foliar N resorption ranged from 6.82 mg/dm(2) (30.7%) in bottomlands to 8.41 mg/dm(2) (37.3%) in slope positions. RMANOVA indicated a sign ificant topographic effect for both absolute and proportional N resorp tion and a significant year effect for absolute N resorption. These si gnificant year effects for P and N stemmed from lowest resorption of n utrients in 1993. The results for P resorption support the hypothesis that foliar resorption is greater in forested sites with lower P ferti lity. However, resorption rates for N did not support the hypothesis c learly, as slopes with intermediate N availability had greater N resor ption rates than did N-rich bottomlands.