Impact of Earthworms on Ecosystems

Earthworms play a crucial role in nutrient cycling by consuming leaves and enriching the soil. However, some ecosystems, like the forests of northern North America, thrived without them. These forests developed thick leaf layers that protected young trees and limited competition. In the 1800s, European earthworms were introduced, disrupting this balance by consuming the leaf litter, which led to fewer young trees and the transformation of forests into grasslands.

What is one of the primary roles of earthworms in the soil ecosystem?

• They produce oxygen for plant roots.

• They consume rocks and minerals.

• They prevent soil erosion by forming barriers.

• They eat leaves and enrich the soil with nutrients.

How did the absence of earthworms benefit the forests of northern North America?

• It led to the growth of more grasslands.

• It allowed for more sunlight to reach the forest floor.

• It increased the population of herbivores.

• It resulted in thick leaf layers that protected young trees.

What was one consequence of the introduction of European earthworms to North American forests?

• Increased biodiversity of plant species.

• Enhanced growth of young trees.

• Transformation of forests into grasslands.

• Improved resistance to frost for seedlings.

Why were young tree seedlings more vulnerable after the introduction of European earthworms?

• They faced increased competition from larger trees.

• They were more susceptible to diseases.

• They had less access to nutrients in the deeper soil.

• They were exposed to more sunlight.

What was a significant change in the ecosystem after European earthworms consumed the leaf litter?

• The forest canopy became denser.

• The soil became more acidic.

• Nutrients were moved to deeper soil layers.

• The number of herbivores increased.