any change in one living or nonliving part of an ecosystem can cause changes in other parts. droughts, storms, and fires, can change ecosystem. some changes harm ecosystem. for example, if a lake dried up during a drought, this may harm the fish or insects that live in the lake or or 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 also die 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 pine cones. heat from a forest fire melts the seal and lest the seeds out.
polluting the air, soil, and water can harm ecosystems. building dams on rivers for electric power and irrigation can harm ecosystems around the rivers. bulldozing wetlands and cutting down forests destroys ecosystems
ecologists are working with companies and governments to find better ways of catching fish, cutting down treees, and bulding dams. they are looking for ways to get food, lumber, and other products for people without causing harm o ecosystems.
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