These values are only approximations and are subject to marked fluctuations because of variations in temperature, fertility, and availability of water.
| Estimated Net Productivity of Certain Ecosystems (in kilocalories/m2/year) | |
|---|
| Temperate deciduous forest | 5,000 |
| Tropical rain forest | 15,000 |
| Tall-grass prairie | 2,000 |
| Desert | 500 |
| Coastal marsh | 12,000 |
| Ocean close to shore | 2,500 |
| Open ocean | 800 |
| Clear (oligotrophic) lake | 800 |
| Lake in advanced state of eutrophication | 2,400 |
| Silver Springs, Florida | 8,800 |
| Field of alfalfa (lucerne) | 15,000 |
| Corn (maize) field, U.S. | 4,500 |
| Rice paddies, Japan | 5,500 |
| Lawn, Washington, D.C. | 6,800 |
| Sugar cane, Hawaii | 25,000 |