Contributions of abundant and rare bacteria to soil multifunctionality depend on aridity and elevation

Biodiversity can effectively actuate ecosystem multifunctionality, and the relationships primarily depend on the circumstances. However, the relative functional importance of particular components in complex biocoenosis, such as abundant and rare taxa, influencing soil multifunctionality changes across environmental gradients and remains limited understanding. Here, 152 independent soil samples from aridity (from 0.47 to 0.97) and elevation (from 142 to 2766 m a.s.l.) gradients across steppes of northern China were collected and analyzed to obtain information of soil bacterial community and soil functional properties, which were further utilized to evaluate how the relationships between the diversities of abundant and rare species and soil multifunctionality respond to changes in aridity and elevation. At aridity and elevation levels of ~0.85 and ~1100 m a.s.l., respectively, abrupt variations of the connections between soil multifunctionality and diversities of abundant or rare taxa occurred. Moreover, the results revealed a significantly positive effect of richness of abundant taxa on soil multifunctionality in the less arid and higher elevation areas, whereas a strongly positive relationship was exhibited between diversity of rare species and soil multifunctionality in the more arid and higher elevation regions. Specially, regardless of higher or lower aridity levels, both contributions of abundant and rare taxa to soil multifunctionality were extremely weak in the lower elevation regions. Our study highlights the importance of aridity and elevation impacting the contributions of abundant and rare taxa in regard to soil multifunctionality, which can positively provide some theoretical bases for promoting ecosystem sustainability and productivity under global climate change.