Looking back in time to reconstruct nitrogen availability trajectories.

The trajectory of nitrogen availability in terrestrial ecosystems over the past century is still poorly understood due to a lack of monitoring and proxy-based reconstructions. For the Northern Great Plains, Brookshire et al. (citation) analyze satellite-based reconstructions of greenness and foliar nutrition and isotopic composition from herbarium samples. I propose that their results of greater productivity coupled with reduced N availability are part of an inflection in our understanding of the global N cycle. Despite assertions of general global eutrophication, much of the terrestrial biosphere appears to be experiencing reduced N availability.