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)
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