When Europeans arrived in New Zealand in the late 1700s and early 1800s they brought with them all kinds of animals that had never existed in this country before, especially rabbits and possums.
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They chewed up the greenery, aided erosion, and generally wrought havoc. Now that widespread possum eradication is taking place in some areas native flora and fauna have a chance to recover. When we moved in to our house 14 years ago there were no tui around, for example. Now there are.
An interesting article today reveals how reintroducing wolves to Yellowstone is helping aspen trees recover: Presence Of Wolves Allows Aspen Recovery In Yellowstone:
After an absence of 70 years, wolves were re-introduced to Yellowstone Park in 1995, and elk populations began a steady decline, cut in half over the past decade. Also, the presence of a natural predator appears to have altered the behavior of the remaining elk, which in their fear of wolves tend to avoid browsing in certain areas where they feel most vulnerable. The two factors together have caused a significant reduction in elk browsing on young aspen shoots, allowing them to survive to heights where some are now above the animal browsing level.
…But the ecological damage, researchers say, went far beyond just trees. The loss of trees and shrubs opened the door to significant stream erosion. Beaver dams declined. Food webs broke down, and the chain of effects rippled through birds, insects, fish and other plant and animal species.
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