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

Tree seedling regeneration in forests is often hindered by the negative impact 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, data from 32 experimental studies were synthesized to assess the overall effect of understory bamboo removal on tree seedling regeneration and identify key influencing factors. Our findings demonstrated positive effects of understory bamboo removal on tree seedling survival, emergence, and height growth. However, we found the response of tree seedlings to bamboo removal varied depending on regeneration characteristics, forest types, and bamboo removal method. Specifically, understory bamboo removal increased the survival rate of deciduous seedlings but did no significantly affect survival rate of evergreen seedlings. Regarding regeneration stages, bamboo removal had a significant positive effect on the survival rate of saplings but not on seedlings. In terms of forest types, bamboo removal significantly increased the emergence density of seedlings in deciduous broadleaf forest, while it had a significant negative influence in evergreen forest and mixed evergreen-deciduous forest. Additionally, the method of bamboo removal was crucial, with seedlings in areas where bamboo was naturally removed showing more robust and favorable responses compared to those where bamboo removal was artificially or animally induced. Furthermore, we found that the duration of bamboo removal and environmental factors such as mean annual temperature, precipitation of seasonality, and soil pH strongly influenced the response ratios of tree seedling regeneration. Our findings provide valuable insights into the ecological implications of understory bamboo removal on tree seedlings regeneration and provide guidance for forest managers in their decision-making processes. These findings can assist forest managers in effectively managing understory bamboo, thereby promoting forest succession and biodiversity conservation.