Answer:
1. The central idea of the passage is that beavers are important restoration landscapers and many park managers are working to bring back their populations.
2. The central idea is stated in the passage.
3. Two details that support the central idea are:
Wetlands created by beavers filter sediments and pollution from streams, reduce flooding and help aquifers recharge.
Beavers provide a protected nursery for baby fish, including salmon.