Spohn, Marie and Arnillas, Carlos Alberto and Bakker, Jonathan D. and Borer, Elizabeth T. and Bråthen, Kari Anne and Cadotte, Marc W. and Carbutt, Clinton and Catford, Jane A. and DuPre, Mary E. and Dwyer, Ciara and Eisenhauer, Nico and Estrada, Catalina and Hagenah, Nicole and Haider, Sylvia and Harms, Kyle E. and Hautier, Yann and Hersch-Green, Erika I. and Knops, Johannes M. H. and Laanisto, Lauri and Laungani, Ramesh and Macek, Peter and Martinson, Holly and Millett, Jonathan and Pärtel, Meelis and Pennings, Steven C. and Peri, Pablo L. and Power, Sally A. and Risch, Anita C. and Roscher, Christiane and Seabloom, Eric W. and Smith, Nicholas G. and Stevens, Carly and Virtanen, Risto and Wardle, Glenda M. and Zhang, Pengfei (2026) Intense solar radiation constrains plant species richness in global grasslands. Proceedings of the National Academy of Sciences of the United States of America, 123 (6): e252712812. ISSN 0027-8424
Full text not available from this repository.Abstract
The search for predictors of plant diversity has challenged scientists for decades. Here we identify intense photosynthetically active radiation (PAR) as a major factor constraining plant species richness in global grasslands. We show that the strength of the negative relationship between species richness and PAR increases with increasing elevation and that species richness is more strongly correlated with intense PAR than with UV-B radiation, climate variables, and atmospheric nitrogen deposition. In addition to species richness, plant biomass was also negatively correlated with PAR at higher elevations, indicating that intense PAR also constrains plant biomass in montane grasslands. Furthermore, we show that the decrease in plant species richness with increasing PAR is mainly caused by a decrease in species richness of forbs, sedges, and rushes. In contrast, species richness of grasses was only negatively correlated with PAR at high elevations, and species richness of legumes was not significantly correlated with PAR. Our results suggest that PAR constrains plant species richness in global grasslands and limits the extent to which plant species of specific functional groups can migrate uphill in response to climate warming.