Vegetation transition from meadow to forest reduces priming effect on SOM decomposition

Meadows and forests are the main vegetation types in temperate terrestrial ecosystems, and largely contribute to soil carbon (C) stock. Bioavailable C inputs can accelerate microbial decomposition of soil organic matter (SOM), which is known as “priming effect”. However, it is still unclear how priming effect, as an important mechanism influencing soil C sequestration, is influenced by spatial transition of vegetation from meadow to forest. To investigate the mechanism of priming effect along a spatial transition gradient of vegetation, a soil incubation experiment with 14C labeled glucose was combined with microbial rDNA sequencing and gene composition prediction. The results showed that with the vegetation transition from meadow to forest soil available phosphorus (P) significantly increased, in contrast to dissolved nitrogen (N) and C which remained unaffected. Moreover, the soil microbial community composition shifted towards a higher relative abundance of K-strategists (Acidobacteria) and a lower abundance of r-strategists (Actinobacteriota) along the vegetation transition from meadow to forest.