Objective  To investigate the undergrowth diversity and soil physical properties in three plantations at Yunyong forest farm in Foshan, Guangdong Province and provide a theoretical basis for ecological forest cultivation and management.

Method  Tutcheria championii was planted in a pure broad-leaved plantation (P1 plot); Cunninghamia lanceolata, Mytilaria laosensis, Elaeocarpus apiculatus, Michelia macclurei, Liquidambar formosana and Alstonia scholarisv were planted in a mixed conifer-broad leaf plantation (P2 plot); M. laosensis, Castanopsis hystri and Erythrophleum fordii were planted in a mixed broad-leaved plantation (P3 plot). Species diversity, coverage, number of total plants and average height of shrub-herb layer under canopy of above plots were investigated. Diversity and evenness indexes were used to study undergrowth species diversity of these plantations. The 100 cm³ cutting ring was used to collect soil samples from the 0-20 cm soil layer at three plots, respectively, and soil physical properties such as water content and bulk density were determined.

Result  The mean values of Shannon-Wiener diversity index and Simpson diversity index of shrub species were lower than herb species while the mean values of evenness indexes of shrub species were larger than herb species in the three plots. The growth status of herb species were superior to shrub species in the three plots. The species number and quantity of the undergrowth of P1 plot were more than those of P2 and P3 plots. The soil bulk density of P1 plot was the highest among the three plots while that of P2 plot was the lowest. The values of total soil porosity, natural moisture content, capillary moisture capacity, capillary porosity, non-capillary porosity and aeration porosity of the three plots were all in the order of P2 plot > P3 plot > P1 plot.

Conclusion  The community structure and soil quality of mixed plantations are better than those of pure plantation.