Elsevie Science and Technology_Biotechnology
The productive ecosystems in the world total an estimated 50 billion hectare, excluding the icecaps. Marine ecosystems occupy approximately 36.5 billion hectare while the terrestrial ecosystems occupy approximately 13.5 billion hectare. Gross primary productivity for the marine ecosystem is estimated to be about 1 t/ha/yr, making the total biomass production about 36.5 billion metric tons or 145×1015 kcal/yr. In contrast, the terrestrial ecosystem produces about 3 t/ha/yr, making the total biomass about 40.5 billion tons or 162×1015 kcal/yr. The total biomass produced is approximately 77 billion tons or about 12.8 t per person per year.
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