It has been reported that applying silicon (Si) to agricultural soils can reduce N₂O emissions. But, we do not fully understand how this might work in forest ecosystems, especially in Phyllostachys edulis plantations. This study set out to determine how exogenous Si impacts soil nitrification and denitrification. Also, it aimed to assess their separate contributions to N₂O emissions. A pot incubation experiment that lasted 28 days was carried out under controlled conditions. The soil used was collected from a bamboo plantation that is intensively managed. The treatments included adding silicon. Also, 3,4-dimethylpyrazole phosphate (DMPP) and acetylene (C₂H₂) were applied to specifically hold back nitrification and denitrification. We measured the rates of soil N₂O emissions, the cumulative fluxes, and the concentrations of NH₄⁺-N, NO₃⁻-N, and NO₂⁻-N. A positive correlation that was significant (p < 0.05) was found between N₂O emissions and the levels of soil NO₃⁻-N. Adding Si continued to reduce both the emission rate and the cumulative flux in all of the treatment groups. Also worth mentioning is that the relative contribution of denitrification to N₂O emissions dropped from 38.2% to 11.4%. Meanwhile, nitrification’s contribution went up from 61.8% to 88.6%. These findings show that adding Si mainly suppresses denitrification. And, by doing so, it lessens N₂O emissions in bamboo plantations. This study underlines the potential of Si amendments. They could be used as an effective management strategy to reduce greenhouse-gas emissions in forest soils. It also provides a scientific basis for making Phyllostachys edulis ecosystems more sustainable.

Tetrastigma hemsleyanum is a valuable medicinal plant whose dryland cultivation typically yields 30–35% lower flavonoid concentration than forest understory systems due to soil and microbial deficiencies. We investigated whether biochar amendment could bridge this quality gap through rhizosphere microecological regulation. Using a split-plot pot experiment with in situ soils from a bamboo forest and a vegetable field, we applied biochar at 2%. Biochar in bamboo forest (MBBC) achieved the highest flavonoid concentrations, exceeding unamended forest and vegetable controls by 22% and 35%, respectively. Biochar effects were habitat-specific. In acidic forest soils (pH 4.95), it raised the pH to 5.61, while in vegetable fields, it boosted leucine aminopeptidase by 159%. Partial least squares path modeling revealed biochar exerted its effects indirectly (indirect effect = 0.88), with soil extracellular enzymes mediating between soil conditions and plant biosynthetic enzymes (PAL, CHS, CHI). Fungal composition was positively associated with biosynthesis (β = 1.68, p < 0.01), particularly Mortierellomycetes, whereas bacterial diversity unexpectedly exhibited a significant negative correlation with it (β = −0.79, p < 0.05). Biochar disrupted Eurotiomycetes dominance in forest soils (from 85% to 39%), creating functionally diverse niches that were associated with enhanced flavonoid accumulation. These findings demonstrate biochar functions as an ecological niche regulator, providing a sustainable strategy for high-quality medicinal plant production in non-native habitats.