Forest ecosystem is mainly distributed in humid and semi-humid areas, and there are many kinds of animals and plants. It is the most biodiversity area in the earth's environment. Forests play an important role in water conservation and soil and water conservation. After the rain falls into the forest, it will first be blocked by the crown of the tree, and then it will flow along the trunk to the ground, and then it will be entangled by the tangled roots. Because the forest soil is loose, some water will seep into the ground and become groundwater, so the water that directly forms runoff from the surface will be much less.

Farmland ecosystem is an artificial ecosystem, its main feature is that people play a key role, and various crops planted by people are the main members of this ecosystem. There are few species of animals and plants in farmland, the community structure is single and the food chain is single and imperfect.

Wetland ecosystem is an ecosystem formed under the condition of excessive moisture and humidity. Swamp is a typical wetland ecosystem, which is dominated by swamp plants and has a wide variety of animals. Wetlands have the functions of purifying water sources, storing floods and fighting drought, and regulating regional microclimate, and are known as kidney of the earth. It has the characteristics of both water and terrestrial ecosystems, has extremely special ecological functions, and is the most important life support system on the earth.

So, the answer is: forest ecosystem; Farmland ecosystem; wetland