Climate reverses directionality in the richness–abundance relationship across the World’s main forest biomes

Abstract

More tree species can increase the carbon storage capacity of forests (here referred to as the more species hypothesis) through increased tree productivity and tree abundance resulting from complementarity, but they can also be the consequence of increased tree abundance through increased available energy (more individuals hypothesis). To test these two contrasting hypotheses, we analyse the most plausible pathways in the richness-abundance relationship and its stability along global climatic gradients. We show that positive effect of species richness on tree abundance only prevails in eight of the twenty-three forest regions considered in this study. In the other forest regions, any benefit from having more species is just as likely (9 regions) or even less likely (6 regions) than the effects of having more individuals. We demonstrate that diversity effects prevail in the most productive environments, and abundance effects become dominant towards the most limiting conditions. These findings can contribute to refining cost-effective mitigation strategies based on fostering carbon storage through increased tree diversity. Specifically, in less productive environments, mitigation measures should promote abundance of locally adapted and stress tolerant tree species instead of increasing species richness.

Renal function and lipid metabolism are major predictors of circumpapillary retinal nerve fiber layer thickness—the LIFE-Adult Study

“…The BIC difference (ΔBIC) was calculated by ΔBIC = BIC model A − BIC model B . A ΔBIC > 2 was regarded as statistically relevant according to Madrigal-González et al [ 16 ], as well as Kass and Raftery [ 17 ].…”

Chronic Disturbance in a Tropical Dry Forest: Disentangling Direct and Indirect Pathways Behind the Loss of Plant Richness

“…Thus, a simplification of the structure is coupled with a decrease in the primary productivity leading to a reduction of species with different photosynthetic characteristics (Ishii et al, 2004;Pau et al, 2012). Although the causal relationships between species richness and productivity remain under discussion, for the SDTFs, it has been proposed that productivity also determines the plant species richness in these forests (Madrigal-González et al, 2020). Additionally, changes in the structural complexity can also induce a loss of diversity without affecting the primary productivity, due to an increase of generalist species that maintain the productivity but exclude specialist species of some canopy strata (Ishii et al, 2004;Clark and Covey, 2012).…”

Terrestrial biomes: a conceptual review

“…Concepts like biomes (developed throughout this review and defined under Final remarks), ecozones, and formations have described such distributions at the regional and global scale due to the importance of this global scale for conservation biology (Chytrý et al 2020) and answering basic ecological questions (Mucina 2019). For example, the biome concept has been used to examine diversity-productivity (Madrigal-González et al 2020) and species-area (e.g., see Dengler et al 2020) relationships, quantify temporal dynamics (Wang and Fensholt 2017), model historical distributions and shifts following climate change (Rowland et al 2016),…”