Understory bamboo removal impacts on woody seedlings regeneration in forest ecosystems: a meta-analysis

Tree seedling regeneration in forests is often impeded by the competitive influence of dense understory bamboo competition. While localized studies have investigated the ecological effects of understory bamboo removal on tree seedlings, but a comprehensive analysis at a global scale is lacking. In this meta-analysis, we synthesized data from 32 experimental studies to assess the overall effect of understory bamboo removal on tree seedling regeneration and identify key influencing factors. Our findings demonstrated that understory bamboo removal enhanced tree seedling survival, emergence, and height growth. However, the response of tree seedlings to bamboo removal varied depending on regeneration characteristics, forest types, and bamboo removal methods. Specifically, understory bamboo removal increased the survival rate of deciduous seedlings but had no significant effect on evergreen seedlings. Regarding regeneration stages, bamboo removal had a significant positive effect on the survival rate of saplings but not on seedlings. In different forest types, bamboo removal significantly increased the emergence density of seedlings in deciduous broadleaf forest but had a significant negative influence in evergreen and mixed evergreen-deciduous forests. Additionally, natural removal of bamboo (i.e., bamboo flowering) showed a greater positive effect on seedlings than bamboo removal by artificial or animal gnawing methods. Furthermore, we found that the duration of bamboo removal, mean annual temperature, precipitation of seasonality, and soil pH strongly influenced the response ratios of tree seedling regeneration. Our findings offer valuable insights into the ecological implications of understory bamboo removal on tree seedlings regeneration, providing guidance for effective understory bamboo management to promote forest succession and biodiversity conservation.