Effects of understory plant diversity on stand type and density in Zengcheng forest farm

It has important guiding significance for scientific and rational forest management and precise improvement of forest quality to study of the effects of different stand types and densities on understory plant composition and species diversity.

Based on the survey data of standard plots of eucalyptus, broad-leaved mixed forest and theropencedrymion in Zengcheng farm, Guangzhou, the effects of different densities in different forest stands on understory plant diversity were investigated using plant diversity analysis and two-factor ANOVA.

(1) There were 121 species of understory plants in 51 families and 92 genera, including 46 species in 37 genera of 23 families of shrubs, 32 species in 27 genera of 15 families of herbs, and 43 species in 31 genera of 20 families of vines. The understory plants under medium and high density conditions had more abundant species among 3 kinds of artificial forests, and the composition of understory shrubs, grasses and lianas was more abundant in medium density broad-leaved mixed forest and high-density theropencedrymion. (2) The dominant species importance value of understory plants decreased with increasing stand density, and the low and medium density mixed forests were more favorable for shrubs to grow into dominant plants, and lianas had higher importance values in theropencedrymion. (3) Plant diversity in the understory of eucalyptus and broad-leaved mixed forests tended to increase and then decrease with increasing density, while plant diversity in the understory of theropencedrymion increased with increasing density. The variability in richness of low and medium density mixed forests and eucalyptus forests was significant, and the plant diversity of theropencedrymion was optimal under high density conditions.

In Zengcheng forest farm, there was a high diversity of understory plants, with mixed forests being richer than pure forests, and theropencedrymion being richer than broad-leaved mixed forests, with medium densities suitable for the growth and reproduction of more understory life types. In the process of improving the quality of forest urban agglomerations in the Pearl River Delta, it is necessary to build native mixed broad-leaved forest, appropriately increase large-diameter precious tree species and coniferous tree species, strengthen forest management of middle and young forests, and take medium stand density, so as to give full play to the multifunctional role of forest urban agglomerations.