Un(der)explored links between plant diversity and particulate and mineral-associated organic matter in soil

Plant diversity can alter soil carbon stocks, but the effects are difficult to predict due to the multitude of mechanisms involved. We propose that these mechanisms and their outcomes can be better understood by testing how plant diversity affects particulate organic matter (POM) and mineral-associated organic matter (MAOM) depending on whether MAOM storage is “saturated” and the total soil organic matter pool is limited by plant inputs. Such context-dependency of plant-diversity effects on POM, MAOM, and total soil organic matter helps explain inconsistencies in plant-diversity–soil-carbon relationships across studies. Further illumination of this context-dependency is required to better predict consequences of biodiversity losses and gains, and manage ecosystems as carbon sinks and nutrient stores. Plant-diversity effects on particulate and mineral-associated organic matter in soil remain underexplored. The authors propose that elucidating the mechanisms underlying these effects can help explain inconsistencies in plant-diversity–soil-carbon relationships across studies and better predict consequences of biodiversity loss/gain for soil carbon stocks.