Foliar‐Nitrogen and Phosphorus Resorption Patterns Differ among Nitrogen‐Fixing and Nonfixing Temperate‐Deciduous Trees and Shrubs

Nutrient resorption from senescing leaves enables plants to conserve nutrients. Low foliar‐nitrogen (N) resorption levels have been estimated in past studies for some N‐fixing woody plant taxa. To determine whether this trait is characteristic of N‐fixing temperate species, N‐resorption proficiency estimates were derived for several species during two seasons in central Illinois, United States. Nutrient‐resorption proficiencies were measured for 24 species of temperate‐deciduous woody plants. Thirteen actinorhizal species and three non‐N‐fixing species in families with actinorhizal species were sampled. One N‐fixing woody legume, four non‐N‐fixing legumes, and two species lacking N‐fixing capabilities and unrelated to these groups were also sampled. Nitrogen resorption, based on resorption proficiency values, was less in N‐fixing species (1.78% N retained in abscised leaves) than in non‐N‐fixing species (1.01% N). Phosphorus (P) resorption, however, was greater in N‐fixing species (0.06% P retained in abscised leaves) than in non‐N‐fixing species (0.26% P). Resorption of P may have been low in a group supporting ectomycorrhizal symbionts. Results indicate a consistent pattern in which N‐fixing species are less proficient at N resorption than other temperate‐deciduous woody species.