seed traps in three 20 m × 20 m plots in the same nature reserve in 2007 and counted the number of germinated seeds. Species basal area in 2023 were from this study. If the total basal area of the community did not change from 2007 to 2023, we can estimate the number of germinated seeds in 2023 from the following equation:
\(\frac{\text{Number\ of\ germinated\ seeds\ in\ 2007}}{\text{Relative\ species\ basal\ area\ in\ 2007}}\)=\(\frac{\text{Number\ of\ germinated\ seeds\ in\ 2023}}{\text{Relative\ species\ basal\ area\ in\ 2023}}\)(2).
The relative species basal area of Q. chungii in 2007 was from a previous study on Q. chungii communities in the same nature reserve (Wang et al. 2011); the relative species basal area in 2023 was from this study. We also estimated the number of germinated seeds in 2023 by assuming a constant proportional relationship between the number of germinated seeds and the average of relative species basal area and abundance, or the number of germinated seeds did not change through time. These two alternative analyses produced qualitatively similar results, thus we did not present them in the paper.