Which of the following statements about secondary succession is true? a.
Secondary succession occurs in ecosystems that have no vegetation.
b.
Secondary succession affects ecosystems that are already established.
c.
Ecosystems require pioneer species to undergo secondary succession.
d.
Secondary succession can occur in areas without soil.

The map above shows where people live in the united states. areas that are darker blue are areas where people live close together. areas that are lighter colors are places where people live farther apart. as a geographer, if you were to study where people live and why they choose to live in these places, which of the six essential elements of geography would you be using?