Two example of ecosystem are - The Agro ecosystem and The Aquatic ecosystem

1. The AgroEcosystem

• Agroecosystem a spatially and functionally coherent unit of agricultural activity. Includes the living and non-living components and their interactions.

• Unlike natural communities or ecosystems, the agroecosystem has clear natural boundaries because of the way humans build fields.The a0groecosystem has clear natural boundaries because of the way humans build fields.

• AgroEcosystems are microcosms of ecology and evolution which are simpler than natural ecosystems.

• Farmers manage agroecosystems.

  • Species diversity is purposefully kept low.

  • Fewer ecological interactions, and many of them are controlled

  • Much of they physical environment is also managed.

Ecology and evolution and agriculture

• 10000 B.C.: harnessed the basics of evolution, largely by accident.

  • Selection for vield, non-shattering

• 10000 B.C. - 1800s: Learned to control ecology in fields.

  • Nutrient tcycling, enemy control, weed

• Machines.

  • (Probably undid some of the ecology understanding)

• 1960s-200s; Genetics

  • Damon

• Today/Future; Data!

  • And you thought pivot tables were useless!

2. Aquatic ecosystem

• Comprises of the marine environment of the sea and fresh water systems in lakes, rivers, ponds and wet lands.

• These ecosystems provide human being with a wealth of natural resources like fish and crustaceans.

• The aquatic ecosystem may be classified as stagnant ecosystem and running water ecosystem.

Pond

• Is a fairly small body of still water

• Most ponds become dry after the rain and get covered by plants for the rest of the year

• When a pond begins to fill during the rains, life forms such as algae and microscopic animals, aquatic insects, snails and worms come out of the floor of the pond

• More complex animals like crabs frogs and fish gradually return to the pond.

• The vegetation in the water consist of floating weeds and rooted vegetation's

Streams and rivers

• These are flowing fresh water bodies

• They act as major transporters of materials from land to sea

• Differ widely in volume of water, speed of flow, oxygen content, temperature etc.

• Composition of plant and animal depend on the source or origin of the river

• The rivers can have sandy, rocky or muddy bed, each type have its own species of plants and animals

Lake

• It is a body of water completely surrounded by land

• It can either be salty or fresh water

• Glaciers move forward, it craves away a deep valley and when ice melts it forms a lake in the valley

• Lakes are short lives surfaces, water can sink into the ground or evaporate into the sky

Ocean and sea

• About $70 \%$ of the world is covered by water and $97 \%$ of this lies in the ocean and sea

• Major effect upon the weather

• Absorbs the suns heat and distributes around the earth warming the air

• Generates rain fall

• Include various carnivores and herbivores fishes

• The area at the mouth of the river where the river joins the sea is called estuary