Wolves That Changed a River Part 2

A decrease in elk population leads to a decrease in size and growth of trees

A decrease in elk population leads to an increase in the size and growth of trees

There is no relationship between the number of elk and the size and growth of the trees.

Between 1995 and 1999 there was only 1 beaver colony.

Between 200 and 2010, the number of colonies increased to 12

The number of willow tree rings peaked in 2010.

Beavers didn´t eat willow trees before 2010.

There were more elk to eat the trees.

Wolves started eating willow trees as elk populations decreased.

Increase in the beaver population corresponds to a decrease in willow size - more beavers eating the willows.

There must have been an increase in the number of elk.