Environmental heterogeneity modulates the effect of plant diversity on the spatial variability of grassland biomass

Daleo, Pedro and Alberti, Juan and Chaneton, Enrique J. and Iribarne, Oscar and Tognetti, Pedro M. and Bakker, Jonathan D. and Borer, Elizabeth T. and Bruschetti, Martín and MacDougall, Andrew S. and Pascual, Jesús and Sankaran, Mahesh and Seabloom, Eric W. and Wang, Shaopeng and Bagchi, Sumanta and Brudvig, Lars A. and Catford, Jane A. and Dickman, Chris R. and Dickson, Timothy L. and Donohue, Ian and Eisenhauer, Nico and Gruner, Daniel S. and Haider, Sylvia and Jentsch, Anke and Knops, Johannes M. H. and Lekberg, Ylva and McCulley, Rebecca L. and Moore, Joslin L. and Mortensen, Brent and Ohlert, Timothy and Pärtel, Meelis and Peri, Pablo L. and Power, Sally A. and Risch, Anita C. and Rocca, Camila and Smith, Nicholas G. and Stevens, Carly and Tamme, Riin and Veen, G. F. (Ciska) and Wilfahrt, Peter A. and Hautier, Yann (2023) Environmental heterogeneity modulates the effect of plant diversity on the spatial variability of grassland biomass. Nature Communications, 14 (1). ISSN 2041-1723

Abstract

Plant productivity varies due to environmental heterogeneity, and theory suggests that plant diversity can reduce this variation. While there is strong evidence of diversity effects on temporal variability of productivity, whether this mechanism extends to variability across space remains elusive. Here we determine the relationship between plant diversity and spatial variability of productivity in 83 grasslands, and quantify the effect of experimentally increased spatial heterogeneity in environmental conditions on this relationship. We found that communities with higher plant species richness (alpha and gamma diversity) have lower spatial variability of productivity as reduced abundance of some species can be compensated for by increased abundance of other species. In contrast, high species dissimilarity among local communities (beta diversity) is positively associated with spatial variability of productivity, suggesting that changes in species composition can scale up to affect productivity. Experimentally increased spatial environmental heterogeneity weakens the effect of plant alpha and gamma diversity, and reveals that beta diversity can simultaneously decrease and increase spatial variability of productivity. Our findings unveil the generality of the diversity-stability theory across space, and suggest that reduced local diversity and biotic homogenization can affect the spatial reliability of key ecosystem functions.