Fig. 1: Context-specific links between plant diversity and particulate organic matter (POM) and mineral-associated organic matter (MAOM).

a Overview of mechanistic links between plant diversity and POM and MAOM. Increases in plant diversity (from left to right) also increase: plant productivity (indicated by more leaves and deeper roots), diversity of litter species and dissolved organic matter/root exudates (indicated by the various colors of leaves and drops), and abundance and diversity of soil fauna and microorganisms. In turn, these changes could increase bioturbation rates and production of feces, grazing of soil fauna on microorganisms, direct sorption (or desorption) of dissolved organic matter on (from) mineral surfaces, and microbial C use efficiency (or other microbial traits), all of which can influence both accumulation and/or decomposition of POM and MAOM. High plant diversity can also affect the microclimate, such as via increased shading, maintenance of soil temperature and moisture (indicated in circles aboveground), or elevated nutrient abundance and availability, which can favor microbial activity/biomass production and the microbial pathway of MAOM formation and decomposition of POM. Arrows indicate processes; “+” and “−“ indicate expected intensification/weakening of processes. Nutrients are indicated by capital “N” and “P.” “+/−” after POM and MAOM indicates that increases in plant diversity can have both positive and negative effects on these pools, and we hypothesize that the direction of plant-diversity effects is context-dependent, as highlighted in panel b. b Relevance of links between increased plant diversity and POM, MAOM, and total SOM in different environmental contexts, including recommendations on how to test these hypotheses; ++, +, o, and − indicate strong and moderate increases, no change, and decreases, respectively. Created in BioRender. Eisenhauer, N. (2025) https://BioRender.com/1hwb0e8.