Ecosystem.
Publié le 15/05/2013
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work.
The tiny bacteria and fungi feed upon the remains of the salmon.
They break down the salmon intochemical nutrients.
Nutrients from the salmon go into the soil.
The roots of plants along the riverbank take up the nutrients.
They use the nutrients to make food.
Inthis way, nutrients get recycled back through the ecosystem.
WHAT CAN HARM AN ECOSYSTEM?
Any change in one living or nonliving part of an ecosystem can cause changes in other parts.
Droughts,storms, and fires can change ecosystems.
Some changes harm ecosystems.
If there is too little rainfall,plants will not have enough water to live.
If a kind of plant dies off, the animals that fed on it may alsodie or move away.
Some changes are good for ecosystems.
Some pine forests need fires for the pine trees to reproduce.The seeds are sealed inside pinecones.
Heat from a forest fire melts the seal and lets the seeds out.
Polluting the air, soil, and water can harm ecosystems.
Building dams on rivers for electric power andirrigation can harm ecosystems around the rivers.
Bulldozing wetlands and cutting down forests destroysecosystems.
Ecologists are working with companies and governments to find better ways of catching fish, cuttingdown trees, and building dams.
They are looking for ways to get food, lumber, and other products forpeople without causing harm to ecosystems.
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