Leaf CNPK concentrations and isotopic signatures

Previous meta-analyses suggested that carnivorous plants – despite access to N, P, and K from prey – have significantly lower leaf concentrations of these nutrients than non-carnivores. Those studies, however, largely compared carnivores in nutrient-poor habitats with non-carnivores in more nutrient-rich sites, so that the differences reported might reflect habitat differences as much as differences in nutrient-capture strategy. Here we examine three carnivorous and 12 non-carnivorous plants in the same nutrient-poor bog to compare their foliar nutrient concentrations, assess their patterns of nutrient limitation using leaf NPK stoichiometry, and estimate %N derived from prey by carnivores using a mixing model for stable N isotopes. We hypothesized that (1) carnivore leaf nutrient concentrations approach or exceed those of non-carnivores in the same nutrient-poor habitat; (2) species in different functional groups show different patterns of stoichiometry and apparent nutrient limitation...