Inflow intensity
We classified species into two groups: low abundance center group and high abundance center group based on the location of their abundance center (Equation 1). Species with abundance center below the midpoint of the elevational gradient of Lebu Valley (3,650 m a.s.l.) are defined as the low abundance center group. Species with abundance center above the midpoint of the elevational gradient are defined as the high abundance center group. Inflow intensity is defined as the difference between the mean abundance center (m) of the low abundance center group and the high abundance center group in each 100-m elevational band (mean abundance center high group – mean abundance centerlow group) (J.-Y. Kim et al., 2019). In elevational bands where only species of one group (high or low abundance center group) were found, the value of the inflow intensity was zero. If the inflow intensity is positively correlated with species richness, the proximity of the range margins of potentially interacting species was considered to contribute to the richness pattern, which indicates that the rescue effect was supported (J.-Y. Kim et al., 2019).