Fig. 4

Estimated model coefficients for linear models predicting understorey non-lignified biomass (R² = 0.60), understorey phosphorus (P) concentration (R² = 0.75) and understorey nitrogen (N) concentration (R² = 0.83). Missing coefficients for some predictors indicate that these terms were not retained in the final models. All forest type coefficients should be interpreted relative to the reference, being the boreal forests in Finland. Error bars indicate 95% confidence intervals. When these include zero, effects can be considered non-significant