2.3 Statistical analysis
In each pot: aboveground biomass (or belowground biomass) was calculated by dividing the aboveground biomass (or belowground biomass) of the four individuals by the pot surface area (i.e. 3.14 × 0.3 m × 0.3 m). Total biomass was calculated by adding the aboveground biomass and belowground biomass, converted to g m−2 via dividing by pot surface area. Ratio of belowground biomass and aboveground biomass (R: S) was calculated by dividing belowground biomass by aboveground biomass.
Curve estimations were applied to explore the relationship between water availability and total biomass, aboveground biomass, belowground biomass and R: S ratio. Then, linear or non-linear regressions were conducted to test the equations of these relationships, where equation with a larger R2 and a significant p value is a better one. All statistics were done with SPSS 21.0.