Linking soil bacterial diversity to ecosystem multifunctionality using backward-elimination boosted trees analysis

There is increasing evidence of linkages between biodiversity and ecosystem functions. Recent interests on this topic have expanded from an individual-function perspective to a multifunction perspective. This study aims to explore the soil bacterial diversity-multifunctionality relationship. Soil bacterial diversity was determined using culture-independent molecular techniques. Bacterial taxa groups with positive effects on certain ecosystem functions were identified by aggregated boosted tree analysis with a prediction-error-based backward-elimination criterion. Soil bacterial diversity-multifunctionality relationship was examined by exploring the relationship between the number of ecosystem functions and the number of soil bacterial taxa. More ecosystem functions would require greater numbers of bacterial taxa, which can be explained potentially using the multifunctional complementarity mechanism. Furthermore, a power law equation, OTU (N) = OTU1(N) (T) , was firstly proposed to describe the observed positive relationship between the soil bacterial diversity and the ecosystem multifunctionality, where OTU (N) is the number of operational taxonomic units (OTUs) required by N functions, while OTU1 is the average number of species required for one function, and T is the average turnover rate of OTU across functions. The number of ecosystem functions would decrease with the loss of soil bacterial diversity. This biodiversity-multifunctionality relationship has an important implication for comprehensively understanding the risk of bacterial diversity loss in relation to the ecosystem functions.