Forest conversion from pure to mixed Cunninghamia lanceolata plantations enhances soil multifunctionality, stochastic processes, and stability of bacterial networks in subtropical southern China

Mixed plantation forest litter improves microbial nitrogen transformation by increasing nitrogen metabolism related genes and key bacterial taxa in northern China

“…Proteobacteria was the key taxa in all litter and soil layers in different planting forests and was highly correlated with organic component decomposition (Pascault et al, 2013). The bacterial key taxa in all forests were Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, Firmicutes, and Candidatus Tectomicrobia, which could drive the litter decomposition and sustain the function of forest ecosystems (Ding et al, 2023). Bacteroidetes and Candidatus Tectomicrobia gradually increased in the MCBP forest, while the proportion of Firmicutes increased in the BP forest.…”

“…Previous studies have shown that mixed plantation increased plant diversity aboveground, and thus increased bacterial α-diversity and changed bacterial β-diversity (Ding et al, 2023;Vitali et al, 2016). Mixed plantation increased the number of bacterial key species and had more keystone taxa (Figure 4d), indicating that mixed litter increased bacterial dominant species and N metabolic function, which tend to be more stable (Ding et al, 2023). The key microbial taxa in different forests were defined by specificity and occupancy values of 0.7 or higher and network analysis.…”

“…Due to the similar litter substrate of BP and CP forests, resulting in the microbial community composition and a stronger association between N metabolism-related enzymes and genes (Ku et al, 2022). The results showed that the substrate composition of pure litter (CP forest or BP forest) was a little different, and the microbial community structure was similar, reducing the consistency between functional enzymes and genes (Ding et al, 2023). For MCBP forest, substrate complexity and diversity of microbial species lead to low consistency of functional enzymes and genes, proving the N metabolic diversity .…”

“…The result of a higher abundance of ammoniation-related gene and DNRA-related gene in MCBP litter promoted the microbial N metabolic process and improved microbial N transformation. Mixed plantation had the potential to accumulate more soil-labile carbon and more litter income, which was more beneficial to the increase of microbial N metabolism genes (Ding et al, 2023). In addition, another explanation was that mixed plantation increased the diversity of plant species and then increased the diversity and input of tree roots, which in turn increased the diversity of rhizosphere microbes and enhanced the microbial metabolic activities, thus promoting the microbial N transformation process (Xu et al, 2023).…”

“…Key species and functional keystones contribute to greater stability of the microbial network, thereby sustaining the stability and function of forest ecosystems (Coyte et al, 2015). Previous studies have shown that mixed plantation increased plant diversity aboveground, and thus increased bacterial α-diversity and changed bacterial β-diversity (Ding et al, 2023;Vitali et al, 2016). Mixed plantation increased the number of bacterial key species and had more keystone taxa (Figure 4d), indicating that mixed litter increased bacterial dominant species and N metabolic function, which tend to be more stable (Ding et al, 2023).…”