Question

select the statement that describes a keystone species and its role in the ecosystem.
the wood stork is sensitive to minor environmental changes, serving as an early warning system for ecologists.
mangrove trees have a complex root system that provides shoreline stabilization and shelter for many species of fish.
lichens produce soil, even in barren conditions, allowing other species to become established within the ecosystem over time.
leeches feed on the blood of a large variety of animals, such as reptiles, birds, and mammals.

Explanation:

A keystone species has a disproportionately large impact on its ecosystem relative to its abundance. Lichens are keystone species as they create soil in barren conditions, enabling other species to colonize. Wood storks are indicator species, mangrove trees are important for shore - line and fish habitat but not classic keystone in the sense of creating habitat from nothing, and leeches are just part of the food - web without the unique keystone role.

Answer:

Lichens produce soil, even in barren conditions, allowing other species to become established within the ecosystem over time.