ObjectiveThe effects of stand density on the community structure and species diversity of Cupressus funebris plantation and the correlation between species diversity and stand factors were explored, providing a basis for the management of Cupressus funebris plantation in Yunding Mountains, southwestern China.

MethodThe research objects were five different stand densities (A−E: 500, 650, 800, 950, 1 100 tree/ha) of 60 years Cupressus funebris in Yunding Mountain, Sichuan Province, southwestern China. The vegetation was investigated by typical plot method. The community structure, species composition and species diversity index (Pielou evenness index Jsw, Simpson dominance index H', Shannon-Wiener diversity index H and species richness index D) were comprehensively analyzed.

Result(1) A total of 170 species of plants were recorded in the study area, belonging to 136 genera and 68 families. The dominant species in shrub layer or herb layer under different densities were mostly shady, shade-tolerant or adaptable plants. (2) With the decrease of stand density, the trend of species diversity index in shrub layer increased first and then decreased. It reached the maximum at density B, with no significant difference except D (P > 0.05). The trend of D, H and H' in herbaceous layer increased first, then decreased, then increased and then decreased. The peak values appeared in density B and D, and there were significant differences among different densities. Stand density and canopy density were negatively correlated with shrub layer D, and significantly positively correlated with herb layer H, H' and J_sw. (3) Distribution between diameter and height structure of density A community was irregular and fluctuated, while distribution of other densities was unimodal. In density B community, medium and large individual trees accounted for a relatively large proportion of individuals, and the stability of the community was better.

ConclusionThe relative optimum stand density of cypress plantation in Yunding Mountain is 650 tree/ha, which is very helpful to maintain the stability of community structure and improve the species diversity under the forest.