Soil microbial life-history strategies covary with above–belowground multifunctionality trade-offs along a mountain elevational gradient
Description
Mountain forest elevational gradients provide natural experiments for testing how climate, substrate heterogeneity and biotic communities jointly regulate ecosystem multifunctionality. However, how soil microbial life-history strategies and microbial interaction structure contribute to above- and belowground multifunctionality trade-offs in forest ecosystems remains poorly understood. Along a temperate mountain forest elevational gradient in Changbai Mountain, northeastern China (800–2000 m), we quantified mineralogical geodiversity, woody plant community composition and trait spectra, microbial co-occurrence network motifs, metagenome-inferred microbial functional strategy spectra, and aboveground, belowground and overall ecosystem multifunctionality. We found that mineralogical geodiversity declined modestly with elevation, whereas ecosystem multifunctionality showed contrasting above- and belowground trends: aboveground multifunctionality decreased with elevation, while belowground multifunctionality increased, producing a clear above–belowground trade-off. Aboveground multifunctionality was most strongly associated with woody plant community composition, suggesting that canopy structure and productivity were primarily plant-driven in this mountain forest system. In contrast, belowground multifunctionality was positively associated with acquisitive woody trait spectra and microbial community compositional shifts linked to microbial network motifs, indicating that plant resource-use strategies and microbial community organization jointly shaped multiple soil functions. Overall multifunctionality covaried most strongly with the dominant microbial life-history strategy gradient derived from metagenome-inferred functional profiles. These results suggest that soil microbial functional strategies provide an important mechanistic link between plant–soil interactions and ecosystem multifunctionality in mountain forests.