Soil properties as key predictors of global grassland production: Have we overlooked micronutrients?
Dajana Radujković, Erik Verbruggen, Eric W. Seabloom, Michael Bahn, Lori Biederman, Elizabeth T. Borer, Elizabeth H. Boughton, Jane A. Catford, Matteo Campioli, Ian Donohue, Anne Ebeling, Anu Eskelinen, Philip A. Fay, Amandine Hansart, Johannes M. H. Knops, Andrew S. MacDougall, Timothy Ohlert, Harry Olde Venterink, Xavier Raynaud, Anita C. Risch, Christiane Roscher, Martin Schütz, Maria L. Silveira, Carly Stevens, Kevin Van Sundert, Risto Virtanen, Glenda M. Wardle, Peter D. Wragg, Sara Vicca
Abstract
Fertilisation experiments have demonstrated that nutrient availability is a key determinant of biomass production and carbon sequestration in grasslands. However, the influence of nutrients in explaining spatial variation in grassland biomass production has rarely been assessed. Using a global dataset comprising 72 sites on six continents, we investigated which of 16 soil factors that shape nutrient availability associate most strongly with variation in grassland aboveground biomass. Climate and N deposition were also considered. Based on theory-driven structural equation modelling, we found that soil micronutrients (particularly Zn and Fe) were important predictors of biomass and, together with soil physicochemical properties and C:N, they explained more unique variation (32%) than climate and N deposition (24%). However, the association between micronutrients and biomass was absent in grasslands limited by NP. These results highlight soil properties as key predictors of global grassland biomass production and point to serial co-limitation by NP and micronutrients.