Understanding Pioneer Species and Primary Succession

What event in 1980 significantly affected the environment around Mount Saint Helens?

• A forest fire

• An earthquake

• A volcanic eruption

• A flood

Which types of organisms were first to appear on the exposed rock after the eruption?

• Birds and mammals

• Bacteria and fungi

• Grasses and flowers

• Trees and shrubs

What is the term used to describe the process of community establishment on bare rock?

• Tertiary succession

• Quaternary succession

• Secondary succession

• Primary succession

Which species are known as pioneer species?

• Grass and bamboo

• Oak and maple trees

• Cacti and succulents

• Lichens and moss

How do lichens contribute to soil formation on rocks?

• By decomposing organic material

• By shading the rock surfaces

• By releasing acids that break down rocks

• By attracting insects

What happens as the pioneer species begin to decay?

• They leave behind organic material

• They absorb more sunlight

• They form new rock layers

• They release toxins

Which type of plants start to grow as soil develops?

• Flowering plants

• Ferns and small weedy plants

• Bushes and shrubs

• Large trees

What is the result of the growth of plants and other life forms in a new ecosystem?

• Decrease in soil quality

• Production of more soil

• Reduction in biodiversity

• Increase in rock formations