Forests Along Rivers in the Pacific Northwest That Have Lost

Forests along rivers in the Pacific Northwest that have lost their salmon populations are less productive because:

A) the dams that prevented the fish from migrating also flooded the forests.
B) the fishers who over-harvested the salmon compacted the soil in the process.
C) the global warming that wiped out the fish has also harmed the trees.
D) the pollution that killed the fish has also directly affected the trees.
E) the nitrogen the fish brought from the ocean and contained in their tissues has been lost.