Abstract:

Taking the sample plots of 50-year-old Platycladus orientalis plantations with different stand densities (1300-5800 plants/hm²) in central mountainous area of Shandong as the research object, the effects of stand density on the richness, diversity, evenness, coverage and biomass of understory vegetation were studied through field investigation and indoor analysis, to provide a basis for the determination of rational density of P. orientalis plantation in the area. The results show that 42 species of plants belonging to 31 families and 38 genera are found in the sample plots. Shrubs are the dominant species. The species diversity index of understory vegetation has strong variability among plots, while the indexes of richness, dominance and evenness are moderate variability. The species richness of understory vegetation decreases significantly with the increase of stand density, and the species diversity index is relatively high when stand density is 2600-3000 plants/hm². Understory coverage, biomass and shrub layer height also show a significant downward trend with the increase of stand density. The results indicate that the understory vegetation of P. orientalis plantation in central mountainous area of Shandong is greatly affected by stand density. When stand density is less than 3000 plants/hm², the species diversity, coverage and biomass of the understory vegetation are relatively good, which is conducive to the formation of a stable ecosystem.

Key words: Platycladus orientalis plantation, stand density, understory vegetation, species diversity, central mountainous area of Shandong