ObjectiveIn the past decades, the surface area of land covered by bamboo (Phyllostachys edulis) in China has rapidly increased. Many studies on bamboo forests have highlighted that bamboo invasion is associated with an increase in the soil pH. The objective of this study was to verify the mechanism by which bamboo invasion increased soil pH as well as to explore the accompanying soil nutrients and microbial properties change trend.MethodA meta-analysis was conducted to test whether the invasions of bamboo into the adjacent forests lead to an increase in soil pH. The changes in soil nutrients and microbial community after the bamboo invasion were also analyzed. In this meta-analysis, 101 sets of data from 42 studies were collected. Besides data from references, 18 sets of data from 12 plots of bamboo invasion zones from experimental plots were also used to analyze soil pH and nutrient change.ResultOverall, the results showed that in all the data sets, 84.9% of the soil pH increased by different amplitude after the bamboo invasion. The magnitude of soil pH increased with invasion time but decreased with soil depth. Also, the increase of soil pH in a coniferous forest(CF)was higher than that in a broadleaf forest (BL). The invasive pure bamboo forest (BB) decreased soil total nitrogen (-15.9%, P < 0.05), nitrate nitrogen (-21.7%, P < 0.05), total organic carbon (-2.0%, P < 0.05), but increased soil available phosphorus (+54.9%, P < 0.05), ammonia nitrogen (+14.7%, P < 0.05) and alkali-hydrolyzable nitrogen (+8.2%, P < 0.05)compared with the original forest. In addition, the bamboo invasion also changed soil microbial community structure and the relative abundance of Actinomycetes was increased (+25.86%, P < 0.05), while that of Acidobacteria (-15.49%, P < 0.05), planctomycetes (-26.66%, P < 0.05) and Bacteroidetes (-22.58%, P < 0.05)was decreased. Based on the meta-analysis results, the ammonia nitrogen was increased while nitrate nitrogen decreased after the bamboo invasion. It could be inferred that the process of ammonification (NH₃+H⁺→NH₄⁺) was improved while nitrification (NH₄⁺+2O₂→NO₃^-+H₂O+2H⁺) was suppressed. Therefore, the possible mechanism of soil pH increase was attributed to the reduction of the accumulation of soil protons released during nitirifcation.ConclusionBamboo invasion into adjacent forests increased soil pH, altered soil chemical properties and microbial community. The effect of bamboo invasion on soil pH is a common phenomenon and the possible mechanism for increasing pH may be related to changes in soil ammonia nitrogen and nitrate nitrogen concentrations.