Multiple regression of the phytomass of the seven most common species against soil and light parameters across all plots.

(a) Soil nitrogen, pH, soil microbial respiration, organic carbon and PAR. (b) The same variables as well as species richness and biomass per plot. β values are standardized coefficients. The absolute value of β coefficients are an index of the importance of that variable as long as it is significant. The r2 values are coefficients of determination of all the variables. ΔAIC = change in AIC from multiple regression containing soil and light variables only. Note that there is an increase in the r2 value in all cases in (b) relative to (a) for each species. ΔAIC < 2 in the cases of E. curvula and E. plana (Table 4b), which is conventionally viewed as an insufficient improvement over the models in Table 4a (Burnham & Anderson 2002). PAR = photosynthetically active radiation.