Monday, December 9, 2019
12:30 - 1:30; 60 min. -
Environmental Science:
How wolves change a river -
Reviewing and continuing with the lesson and graph from last week, Rory and I discussed how bringing wolves to the island where deer populations had increased unchecked to the point of decimating the plant populations. We reviewed how the wolves, over time had brought the deer population into balance. I challenged Rory to surmise how other populations reacted to the wolf population. We then watched the sustainable human video on trophic cascades entitled: ‘How Wolves Change Rivers’, which describes the effect of re-introducing wolves to the Yellowstone National Park after 75 years absence. We then discussed how the deer of Yellowstone avoided areas, in which plant populations recovered in a short amount of time, bringing song birds and small mammals. As the ecosystem repaired, the plants forced the rivers to stay in a more narrow, consistent area. This made the banks deeper and more established, changing the behavior of the rivers. Ultimately the diversity of Yellowstone Park has increased with the addition of a top predator.