People have dramatically increased food production from the world’s ecosystems, in part by converting large areas to highly managed agroecosystems -- croplands, pastures, feedlots -- that provide the bulk of the human food supply.

The condition of agroecosystems from the standpoint of food production is mixed.

Although crop yields are still rising, the underlying condition of agroecosystems is declining in much of the world. Soil degradation is a concern on as much as 65 percent of agricultural land.

Historically, inputs of water, fertilizers, and technologies such as new seed varieties and pesticides have been able to more than offset declining ecosystem conditions worldwide (although with significant local and regional exceptions), and they may continue to do so for the foreseeable future.

But how long can that kind of compensation continue? The diminishing capacities of agroecosystems will make that task ever more challenging.

The outlook for fish production -- also a major source of food -- is more problematic. The condition of coastal ecosystems from the standpoint of food production is only fair and becoming worse.

Twenty-five percent of the world’s most important marine fish stocks are depleted, overharvested, or just beginning to recover from overharvesting. Another 44 percent are being fished at their biological limit and are, therefore, vulnerable to depletion.

Freshwater fisheries present a mixed picture; we are currently overexploiting most native fish stocks, but introduced species have begun to enhance the harvest in some areas.

Overall, the pattern of growing dependence on aquaculture and the decline of natural fish stocks will have serious consequences for many of the world's poor who depend on subsistence fishing.

Agroecosystems	Coastal ecosystems	Forest ecosystems	Freshwater systems	Grassland ecosystems