CHANGES IN ECOSYSTEMS
There are some changes that don’t affect the overall balance of an ecosystem, but there are other changes that can greatly affect the balance. These changes can destroy an ecosystem.

Natural changes in ecosystems
These changes don´t alter the balance of the ecosystems:

• Night and day: light and temperature.
• Seasons: weather.
• Tides: water levels.
• Migration of animals.
• Human activities: seeding, planting and harvesting.

Harmful changes in ecosystems
These changes cause migration or death in living organisms. Ecosystems can´t recover easily or they are permanently altered.

• Natural disasters.
• Excessive hunting, fishing or harvesting.
• Disease.Pollution. 
• Building.

How do ecosystems change from Reem Bakr

ANIMALS  AND  PEOPLE

Animals provide us with useful and important things like:

• food
• materials
• work
• company

Farm animals from esccalbe

CATTLE are animals that we breed for food or materials. Livestock farming is the activity that involves breeding cattle.

• Mammals, like cows and bulls, sheep, goats, pigs or rabbits.
• Birds, like chickens, turkeys, ducks or ostriches. The breeding of birds is called poultry farming.
• Aquatic animals, like fish and shellfish. The breeding of these types of animals is called fish farming.