Foliar ẟN patterns in legumes and non-N fixers across a climate gradient, Hawai'i Island, USA.

Recent studies from the Hawaiian Islands showed that pedogenic thresholds demarcate domains in which rock-derived nutrient dynamics remain similar across wide variations in rainfall. These thresholds appear related to certain aspects of N cycling, but the degree to which they correspond to patterns of biological N fixation (BNF)-the dominant input of N into less-managed ecosystems-remains unclear. We measured aboveground plant biomass, foliar nutrient concentrations, and foliar δN along a climate gradient on ~ 150,000-year-old basaltic substrate to characterize foliar N sources and spatially relate them to soil nutrients.