Fig. 1. Bivariate relationships between endogenous (dependent) and exogenous (independent) variables, for all hypothesized causal paths in the structural equation model (SEM). All
numerical variables were natural logarithm-transformed and standardized. (a) Aboveground biomass (AGB, Mg ha−1
) vs. stand quality; (b) DBH variation vs. stand quality; (c) species
diversity vs. stand quality; (d–f) DBH variation, species diversity, and AGB vs. stand quality; and (g–h) AGB vs. DBH variation and species diversity. Fitted regression is significant at
P b 0.05 and the relationships without fitted lines are non-significant at P N 0.05 (n = 45). Boxplots show the 10th to 90th percentile of the data; (n = 38); different stand quality
levels sharing different letters represent significant differences (P b 0.05; Tukey's test).