Nutrition-addition measurements
Similar to the index of competition intensity, we quantified the nutrition-addition effect with LnRR:
\begin{equation} Nutrition-addition\ effect=ln\frac{\text{Biomass}_{h\text{igh\ nutrition}}\ }{\text{Biomass}_{\text{low\ nutrition}}}\nonumber \\ \end{equation}
Where \(\text{Biomass}_{\text{high\ nutrition}}\) is the biomass of the target species (S. grandis or S. krylovii ) grown under high nutrition treatment, and \(\text{Biomass}_{\text{low\ nutrition}}\)is the average biomass of the target species (S. grandis orS. krylovii ) grown under low nutrition treatment. The nutrition-addition effect was calculated within each target species (2) and plantation condition (4) cross-treatment, respectively.