Figure 3 Two-dimensional plot distributions of biomass and number of RPs of the plots labelled by ICNs (row 1) and TCNs (row 2), respectively. The ellipse area is the 95% confidence region of the sample distribution. The left two panels show the plot distributions under different N addition rates (N<15 g N m-2 year-1(green circle); N≥15 g N m-2 year-1(pink circle)). The middle two panels are the plot distributions under mowing (black circle) and no mowing (red circle). The right two panels are the plot distributions under N addition frequencies (zero (sienna circle), twice a year (blue circle), monthly (orange circle)).