Fig. 5From: Different responses of soil respiration and its components to nitrogen and phosphorus addition in a subtropical secondary forestThe relative contributions of driving factors on autotrophic respiration (Ra) and heterotrophic respiration (Rh). The variable importance values are derived from 100 runs of random forest analysis including driving factors as moderators in the model. *P < 0.05, **P < 0.01, ***P < 0.001Back to article page