Anthropogenic nitrogen deposition predicts local grassland primary production worldwide

Stevens, Carly J. and Lind, Eric M. and Hautier, Yann and Harpole, W. Stanley and Borer, Elizabeth T. and Hobbie, Sarah and Seabloom, Eric W. and Ladwig, Laura and Bakker, Jonathan D. and Chu, Chengjin and Collins, Scott and Davies, Kendi F. and Firn, Jennifer and Hillebrand, Helmut and Pierre, Kimberly J. La and Macdougall, Andrew and Melbourne, Brett and Mcculley, Rebecca L. and Morgan, John and Orrock, John L. and Prober, Suzanne M. and Risch, Anita C. and Schuetz, Martin and Wragg, Peter D. (2015) Anthropogenic nitrogen deposition predicts local grassland primary production worldwide. Ecology, 96 (6). pp. 1459-1465. ISSN 0012-9658

Abstract

Humans dominate many important Earth system processes including the nitrogen (N) cycle. Atmospheric N deposition affects fundamental processes such as carbon cycling, climate regulation, and biodiversity, and could result in changes to fundamental Earth system processes such as primary production. Both modelling and experimentation have suggested a role for anthropogenically altered N deposition in increasing productivity, nevertheless, current understanding of the relative strength of N deposition with respect to other controls on production such as edaphic conditions and climate is limited. Here we use an international multiscale data set to show that atmospheric N deposition is positively correlated to aboveground net primary production (ANPP) observed at the 1-m2 level across a wide range of herbaceous ecosystems. N deposition was a better predictor than climatic drivers and local soil conditions, explaining 16% of observed variation in ANPP globally with an increase of 1 kg N·ha−1·yr−1 increasing ANPP by 3%. Soil pH explained 8% of observed variation in ANPP while climatic drivers showed no significant relationship. Our results illustrate that the incorporation of global N deposition patterns in Earth system models are likely to substantially improve estimates of primary production in herbaceous systems. In herbaceous systems across the world, humans appear to be partially driving local ANPP through impacts on the N cycle.