List three reasons how the absence of frogs/tadpoles affect the forest ecosystems.

By the year 1993, 500 species of frogs have gone extinct in the forest ecosystems because of pollution, harvesting, diseases, and habitat destruction. They are important in the ecosystem because of the following reasons: 

a. Frogs are important in the food web. They are an important food source for animals like birds and snakes therefore the absence of this animal will have an effect on the cascade of predator-prey in the ecosystem. 

b. Frogs are very important bio-indicators. They are important in determining whether the environment is habitable and is suitable for other life forms because they require land and water habitats to survive. They have skins that are permeable and can easily absorb toxins in the environment. The health of the frog and the way it adapts in the environment is indicative of the health of the biosphere as a whole.

c. Frogs keep waterways clean by feeding on algae and they feed on large quantities of insects that can possibly transmit diseases that are fatal to humans.