Simulated carbon balance for the Chequamegon-Nicolet National Forest (CNNF), 2000–2008. The left y-axis refers to the net system production (NSP) and forest net biome production (NBP) per unit of forest area. The right y-axis is scaled to the industrial forest C cycle emissions per unit of forest area for the entire CNNF (ET) and its hardwood (EH) and conifer (EC) components. Hardwood and conifer emissions are per unit area of each forest type. The bar plot (grey) shows harvest area (103 ha) in each year.