Global Rate of Production
Net primary production is the rate at which new biomass is generated, mainly due to photosynthesis. Global primary production can be estimated from satellite observations. Satellites scan the normalised difference vegetation index (NDVI) over terrestrial habitats, and scan sea-surface chlorophyll levels over oceans. This results in 56.4 billion tonnes C/yr (53.8%), for terrestrial primary production, and 48.5 billion tonnes C/yr for oceanic primary production. Thus, the total photoautotrophic primary production for the Earth is about 104.9 billion tonnes C/yr. This translates to about 426 gC/m²/yr for land production (excluding areas with permanent ice cover), and 140 gC/m²/yr for the oceans.
However, there is a much more significant difference in standing stocks—while accounting for almost half of total annual production, oceanic autotrophs account for only about 0.2% of the total biomass. Autotrophs may have the highest global proportion of biomass, but they are closely rivaled or surpassed by microbes.
Terrestrial freshwater ecosystems generate about 1.5% of the global net primary production.
Some global producers of biomass in order of productivity rates are
| Producer | Biomass productivity (gC/m²/yr) |
Ref | Total area (million km²) |
Ref | Total production (billion tonnes C/yr) |
|---|---|---|---|---|---|
| Swamps and Marshes | 2,500 | ||||
| Tropical rainforests | 2,000 | 8 | 16 | ||
| Coral reefs | 2,000 | 0.28 | 0.56 | ||
| Algal beds | 2,000 | ||||
| River estuaries | 1,800 | ||||
| Temperate forests | 1,250 | 19 | 24 | ||
| Cultivated lands | 650 | 17 | 11 | ||
| Tundras | 140 | ||||
| Open ocean | 125 | 311 | 39 | ||
| Deserts | 3 | 50 | 0.15 |
Read more about this topic: Biomass (ecology)
Famous quotes containing the words global, rate and/or production:
“As the global expansion of Indian and Chinese restaurants suggests, xenophobia is directed against foreign people, not foreign cultural imports.”
—Eric J. Hobsbawm (b. 1917)
“Unless a group of workers know their work is under surveillance, that they are being rated as fairly as human beings, with the fallibility that goes with human judgment, can rate them, and that at least an attempt is made to measure their worth to an organization in relative terms, they are likely to sink back on length of service as the sole reason for retention and promotion.”
—Mary Barnett Gilson (1877–?)
“Constant revolutionizing of production ... distinguish the bourgeois epoch from all earlier ones. All fixed, fast-frozen relations, with their train of ancient and venerable prejudices are swept away, all new-formed ones become antiquated before they can ossify. All that is solid melts into air, all that is holy is profaned, and man is at last compelled to face with sober senses, his real conditions of life, and his relations with his kind.”
—Karl Marx (1818–1883)