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

Background Tree seedling regeneration in forests is often hindered by the competitive influence of dense understory bamboo competition. While localized studies have investigated the ecological effects of understory bamboo removal on tree seedlings, a comprehensive analysis at a global scale is lacking. In this meta-analysis, we synthesized 497 observations from 32 experimental studies to assess the overall effects of understory bamboo removal on tree seedling regeneration. Results The results showed 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. For regeneration stages, bamboo removal had a significant positive effect on the survival rate of saplings but not on seedlings. Regarding differences across forest types, bamboo removal significantly increased the emergence density of seedlings in deciduous broadleaf forests but had a significant negative influence in evergreen and mixed evergreen-deciduous forests. Additionally, natural removal of bamboo 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. Conclusions Our meta-analysis demonstrates the significant effects of understory bamboo removal on multiple facets of tree seedling dynamics across different regeneration characteristics, forest types, and bamboo removal methods. In addition, our study emphasizes that the duration of bamboo removal, climate, and soil pH have a critical effect on tree seedling regeneration. Our findings elucidate the effects of understory bamboo removal on seedling regeneration, offering robust scientific insights for sustainable forest management.