Intense solar radiation constrains plant species richness in global grasslands

M Marie Spohn (Department of Soil and Environment, Swedish University of Agricultural Sciences) C Carlos Alberto Arnillas (Department of Physical and Environmental Sciences, University of Toronto Scarborough) J Jonathan D. Bakker (School of Environmental and Forest Sciences, University of Washington) E Elizabeth T. Borer (Department of Ecology, Evolution, and Behavior, University of Minnesota) K Kari Anne Bråthen (Department of Arctic and Marine Biology, UiT The Arctic University of Norway) M Marc W. Cadotte (Department of Biological Sciences, University of Toronto Scarborough) C Clinton Carbutt (School of Agriculture and Science, University of KwaZulu-Natal) J Jane A. Catford (Department of Geography, King’s College London) M Mary E. DuPre (MPG Ranch) C Ciara Dwyer (Centre for Environmental and Climate Science, Lund University) N Nico Eisenhauer C Catalina Estrada (Department of Life Sciences, Imperial College London) N Nicole Hagenah S Sylvia Haider (Vegetation Ecology and Biodiversity Conservation Group, Institute of Ecology, Leuphana University of Lüneburg) K Kyle E. Harms (Department of Biological Sciences, Louisiana State University) Y Yann Hautier E Erika I. Hersch-Green (Department of Biological Sciences, Michigan Technological University) J Johannes M. H. Knops (Department of Health and Environmental Sciences, Xi’an Jiaotong-Liverpool University) L Lauri Laanisto R Ramesh Laungani (Department of Environmental Science and Policy, Marist College) P Peter Macek (Chair of Biodiversity and Nature Tourism, Estonian University of Life Sciences) H Holly Martinson (Department of Biology, McDaniel College) J Jonathan Millett (Department of Geography & Environment, Loughborough University) M Meelis Pärtel S Steven C. Pennings (Department of Biology and Biochemistry, University of Houston) P Pablo L. Peri S Sally A. Power (Hawkesbury Institute for the Environment, Western Sydney University) A Anita C. Risch (Swiss Federal Institute for Forest, Snow and Landscape Research WSL) C Christiane Roscher (German Centre for Integrative Biodiversity Research, Halle-Jena-Leipzig) E Eric W. Seabloom (Department of Ecology, Evolution, and Behavior, University of Minnesota) N Nicholas G. Smith (Department of Biological Sciences, Texas Tech University) C Carly Stevens (Lancaster Environment Centre, Lancaster University) R Risto Virtanen G Glenda M. Wardle (School of Life and Environmental Sciences, ARC Training Centre in Data Analytics for Resources and Environments, The University of Sydney) P Pengfei Zhang

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.

Article Details

Volume / Issue Vol. 123, Issue 6
Published February 10, 2026
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (35)

M

Marie Spohn

Department of Soil and Environment, Swedish University of Agricultural Sciences

C

Carlos Alberto Arnillas

Department of Physical and Environmental Sciences, University of Toronto Scarborough

J

Jonathan D. Bakker

School of Environmental and Forest Sciences, University of Washington

E

Elizabeth T. Borer

Department of Ecology, Evolution, and Behavior, University of Minnesota

K

Kari Anne Bråthen

Department of Arctic and Marine Biology, UiT The Arctic University of Norway

M

Marc W. Cadotte

Department of Biological Sciences, University of Toronto Scarborough

C

Clinton Carbutt

School of Agriculture and Science, University of KwaZulu-Natal

J

Jane A. Catford

Department of Geography, King’s College London

M

Mary E. DuPre

MPG Ranch

C

Ciara Dwyer

Centre for Environmental and Climate Science, Lund University

N

Nico Eisenhauer

C

Catalina Estrada

Department of Life Sciences, Imperial College London

N

Nicole Hagenah

S

Sylvia Haider

Vegetation Ecology and Biodiversity Conservation Group, Institute of Ecology, Leuphana University of Lüneburg

K

Kyle E. Harms

Department of Biological Sciences, Louisiana State University

Y

Yann Hautier

E

Erika I. Hersch-Green

Department of Biological Sciences, Michigan Technological University

J

Johannes M. H. Knops

Department of Health and Environmental Sciences, Xi’an Jiaotong-Liverpool University

L

Lauri Laanisto

R

Ramesh Laungani

Department of Environmental Science and Policy, Marist College

P

Peter Macek

Chair of Biodiversity and Nature Tourism, Estonian University of Life Sciences

H

Holly Martinson

Department of Biology, McDaniel College

J

Jonathan Millett

Department of Geography & Environment, Loughborough University

M

Meelis Pärtel

S

Steven C. Pennings

Department of Biology and Biochemistry, University of Houston

P

Pablo L. Peri

S

Sally A. Power

Hawkesbury Institute for the Environment, Western Sydney University

A

Anita C. Risch

Swiss Federal Institute for Forest, Snow and Landscape Research WSL

C

Christiane Roscher

German Centre for Integrative Biodiversity Research, Halle-Jena-Leipzig

E

Eric W. Seabloom

Department of Ecology, Evolution, and Behavior, University of Minnesota

N

Nicholas G. Smith

Department of Biological Sciences, Texas Tech University

C

Carly Stevens

Lancaster Environment Centre, Lancaster University

R

Risto Virtanen

G

Glenda M. Wardle

School of Life and Environmental Sciences, ARC Training Centre in Data Analytics for Resources and Environments, The University of Sydney

P

Pengfei Zhang