Dryas and alders in Glacier Bay, and dwarf lupines on the Pumice Plain of Mount St.Helens, all have root nodules containing nitrogen-fixing bacteria.Why were these plants important to the development of communities on these two primary succession sites?
A) The nitrogen they produced added to nitrogen already available on the sites.
B) They could remove excess nitrogen from the site so they would not be poisoned.
C) They shared their nitrogen with other plants already colonizing the sites.
D) The nitrogen provided strong roots that allowed them to colonize in soil-free areas.
E) They could colonize first and leave nutrients and habitat for subsequent colonizers.

Question

Quizplus · Accepted Answer

Plants that are able to colonize first in primary succession sites are important in facilitating the development of communities because they can establish and stabilize the soil, provide shelter and food for animals, and leave behind nutrients that subsequent colonizers can utilize. The nitrogen-fixing ability of these plants is not as significant as their ability to colonize and establish on barren sites.

Dryas and Alders in Glacier Bay, and Dwarf Lupines on the Pumice