Abstract:

Analysis of the factors influencing understory herbaceous diversity in Chinese fir plantations can provide a theoretical basis for the sustainable management of forests in China’s southern mountain area. Based on the data collected from 115 Chinese fir plantations， the relationship between environmental factors， stand structure and herb diversity in Chinese fir plantations was investigated using correlation analysis， variance decomposition analysis and a structural equation model. The maximum entropy model was used to simulate the potential geographical distribution of understory plant diversity in Chinese fir plantations. The results showed that： 1） The interpretation rates of the single effect of climate factors and the common effect of climate and terrain factors were 19.31% and 12.34%， respectively. 2） Mean annual precipitation and canopy cover had significant effects on understory herb diversity （P<0.01）， and the total influence coefficients were 0.72 and -0.49， respectively. Altitude， annual temperature， soil organic matter and total nitrogen content had significant effects on understory plant diversity （P<0.05）， and the total influence coefficients were -0.33， 0.17， 0.23 and 0.34， respectively. 3） The main environmental factors and their contribution rates of understory herb diversity in Chinese fir plantation were： mean annual precipitation （37.1%）>altitude （19.5%）>mean annual temperature （15.2%）>soil organic matter （8.9%）>soil total nitrogen （7.5%）， and the cumulative contribution rate was 88.2%. 4） Understory herbaceous diversity was greater in areas with mean annual precipitation ≥1650 mm， mean annual temperature 18-22 ℃， mid-low altitude （510-680 m）， and soil organic matter content ≥20 g·kg^-1.

Key words: stand structure, environmental factors, herbaceous diversity, structural equation model, maximum entropy model