Table 2 Linear model results of the time series analysis of DDG variables (Dmax and Rmax) across richness components for each lake. Here, +: positive slope of linear model (Meaning for Dmax: becomes shallower; Meaning for Rmax: more species); −: negative slope of linear model (Meaning for Dmax: becomes deeper; Meaning for Rmax : less species); significance levels of p-values: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1