Effects of stand age on allometric relationship between leaf mass and leaf area in Cunninghamia lanceolata

Objective Based on the hypothesis of “diminishing return”, this study investigates the allometric relationship between leaf mass and leaf area in Chinese fir across a chronosequence of stand ages, with an emphasis on identifying stage-specific patterns associated with forest development.

Method Chinese fir plantations aged 4, 10, 18, 23, 28, and 39 years at the Huitong Chinese Fir Forest Ecosystem National Field Observation and Research Station in Hunan Province, central China were selected. The diminishing-return patterns and age-related variations in the relationship between fresh leaf mass and fresh leaf area as well as dry leaf mass and dry leaf area were examined.

Result (1) The allometric scaling exponent (α) for both fresh leaf mass-fresh leaf area and dry leaf mass-dry leaf area differed significantly among stand ages (P < 0.05). With the exception of fresh leaf mass-fresh leaf area exponent in 39-year-old stands, which was significantly greater than 1, all other α values were significantly less than 1. (2) Overall, α values for fresh leaf mass-fresh leaf area were consistently lower than those for dry leaf mass-dry leaf area, and the fresh leaf mass-fresh leaf area relationship exhibited higher goodness of fit (R²). These results indicated a stronger coupling between fresh leaf mass and fresh leaf area than dry leaves.

Conclusion The allometric relationships of Chinese fir leaves are strongly regulated by stand age, reflecting dynamic adjustments in resource investment and return during leaf development. These findings provide new insights into the adaptive strategies of leaf functional traits during plantation development and offer scientific guidance for resource management and productivity enhancement in Chinese fir plantations.