Foliar resorption in nitrogen-fixing and non-fixing species in a swamp forest in northern Turkey

Abstract

Foliar resorption of nutrients in plants is a key factor to conserve nutrients especially nitrogen (N) and phosphorus (P) and makes plant species less-dependent to soil nutrient status. There is much debate whether N-fixing and non-fixing species differ or not with respect to N and P usage strategies. Two N-fixing (one actinorhizal and one legume) and four non-fixing species were sampled in a swamp forest in northern Turkey to compare nitrogen-fixing and non-fixing species with respect to resorption efficiency (RE) and resorption proficiency (RP). Actinorhizal and legume species were Alnus glutinosa (L.) Gaertner subsp. glutinosa and Robinia pseudoacacia L., respectively. Non-fixing species were Quercus hartwissiana Stcv., Acer campestre L. subsp. campestre, Euonymus europaeus L. and Fraxinus excelsior L. It has been found that N-fixing species had lower NRE than non-fixing species in the present study, while N-fixing species were more P-proficient than non-fixing species (except for F. excelsior). Additionally, N/P ratios of N-fixing species were higher than those of non-fixing species. Foliar resorption was not highly proficient in both N-fixing and non-fixing species in the present study.