• determinants analysis;
  • ecological restoration;
  • plant diversity;
  • plantation;
  • understory vegetation

Plantations cover large areas in many countries, and the enhancement of plantation biodiversity is an increasingly important ecological concern. Many studies have demonstrated that overstory composition is important because it influences understory regeneration. To compare the understory vegetation and analyze its determinant factors, six typical plantations in South China were investigated: Acacia mangium plantation, Schima superba plantation, Eucalyptus citriodora plantation, E. exserta plantation, mixed-coniferous plantation, and mixed native species plantation. The results show that native species plantations shaded out more grasses and herbs than exotic species plantations, mixed-species plantations recruited more understory species than monoculture plantations, the leguminous species plantation had higher soil nitrogen than nonleguminous species plantations, and understory vegetation in the mixed-coniferous plantation was similar to that of mixed, native broadleaf species plantation. Although light is the crucial environmental factor affecting the understory community and diversity among the 14 measured factors, other environmental variables such as soil nutrients and soil moisture are also important.