Table 2.

Baseline and projected ecosystem carbon stock, and density, and annual sequestration rate as of 2050 for each ecosystem of federal lands across CONUS

Carbon measurement	Unit	SRES scenario	Cropland	Forest	Grassland	Hay/pasture	Mech_ disturbed	Other	Shrubland	Wetland	Sum/mean	SD
Carbon stock*	1012 g C	Baseline	53	8,728	604	55	68	60	1,389	656	11,613
	% of total		0.5	75.2	5.2	0.5	0.6	0.5	12.0	5.6	100
Carbon density	Mg C⋅ha−1		36.6	128.3	27.4	29.6	74.2	4.6	18.9	151.3	62.7
	SD		10.1	19.5	4.6	9.3	24.6	2.9	5.0	51.6	27.0
Carbon stock†	1012 g C	A1B	105	10,300	805	108	188	64	1,320	876	13,766
		A2	93	10,363	817	94	166	65	1,339	874	13,811
		B1	69	10,674	828	62	102	58	1,348	877	14,017
		Average	89	10,446	817	88	152	62	1,336	876	13,865	134
NECB‡	1012 g C	Average	36	1,718	213	33	84	2	−53	220	2252
Carbon density	Mg C⋅ha−1	Average	45.9	156.2	37.7	36.9	98.2	4.6	18.3	201.9	74.8	75.1
		Change§	9.3	27.9	10.3	7.3	24.0	0.0	−0.6	50.6	12.2	17.3
		SD	3.7	17.9	1.7	2.7	13.6	0.2	0.7	19.6	7.5
Carbon sequestration rate¶	kg C⋅ha−1⋅y−1	A1B	212	604	227	177	556	2	−16	1,159	258	393
		A2	214	615	227	179	541	4	−13	1,138	264	386
		B1	192	639	231	117	484	−6	−11	1,074	288	373
		Mean	207	620	228	163	534	0	−13	1,124	270	383
		SD	82	398	37	61	303	5	17	436	168

^*Ecosystem carbon stock, including aboveground and belowground biomass and soil organic carbon in the top 20-cm depth of soil from the average of three carbon simulation models.

^†Ecosystem carbon stock, including aboveground and belowground biomass and soil organic carbon in top 20-cm depth of soil, averaged from three carbon simulation models with three GCM climate data and three SRES scenarios A1B, A2, and B1.

^‡Net ecosystem carbon budget (NECB) between 2006 and 2050, or NECB = C Stock₂₀₅₀ − C Stock₂₀₀₅.

^§Change in megagrams of carbon per hectare as of 2050 from the baseline 2005 for the same ecosystem of all federal lands.

^¶Annual carbon sequestration rate averaged of the period from 2006 through 2050.