Fig. 3From: Effect of nitrogen addition on soil CO2 efflux and fine root biomass in maple monocultures of the hyrcanian regionRelationships between soil CO2 efflux and soil temperature measured at different levels of N addition (N0: Control, N1: 5, N2: 10, and N3:15 g N m−2 year−1); Std. Err. Est standard error of estimate, NRSME normalized RMSEBack to article page