Table 1 Major plant communities of the earth, with their area, their net primary production, and the amount of carbon they hold in storage. Net primary production is the amount of carbon a plant community provides annually for harvesting or for the support of various consumer organisms, either wild or domesticated. Although only about 30% of the earth's surface is covered by land, the net primary production of terrestrial vegetation is slightly more than twice the primary production of the oceans. The quantity of carbon stored in land plants is some 500 times greater than the quantity stored in marine ecosystems. The carbon stored in trees is roughly equal to the carbon in the atmosphere.
Plant community	Area (106 sq. km)	Net primary production (109 metric tons of carbon per year)	Plant mass (109 metric tons of carbon)
Tropical rainforest	17.0	16.8	344.0
Tropical seasonal forest	7.5	5.4	117.0
Temperate evergreen forest	5.0	2.9	79.0
Temperate deciduous forest	7.0	3.8	95.0
Boreal forest	12.0	4.3	108.0
Woodland and shrubland	8.5	2.7	22.0
Savannah	15.0	6.1	27.0
Temperate grassland	9.0	2.4	6.3
Tundra and alpine meadow	8.0	0.5	2.3
Desert scrub	18.0	0.7	5.9
Rock, ice and sand	24.0	0.03	0.2
Cultivated land	14.0	4.1	6.3
Swamp and marsh	2.0	2.7	13.5
Lake and stream	2.0	0.4	0.02
Total continental	149.0	52.8	826.5
Open ocean	332.0	18.7	0.45
Upwelling zones	0.4	0.1	0.004
Continental shelf	26.6	4.3	0.12
Algal bed and reef	0.6	0.7	0.54
Estuaries	1.4	1.0	0.63
Total marine	361.0	24.8	1.74
World total	510.0	77.6	828.0

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