They are sensitive indicators of air and water pollution, and play important roles in the cycling of water and nutrients and in relationships with many other plants and animals.
(They; are; sensitive indicators of air and water pollution) (They; play; important roles; L:in the cycling of water and nutrients and in relationships with many other plants and animals)
They They
are play
sensitive indicators of air and water pollution
important roles L:in the cycling of water and nutrients and in relationships with many other plants and animals