David Rockefeller, the billionaire philanthropist who gave generously of his time and wealth to help preserve Maine’s natural beauty during his long life, has left more than $25 million to various Maine institutions. Rockefeller, who died March 20 at the age of 101, left $20 million to the Land and Garden Preserve of Mount Desert Island in Seal Harbor as well as money and property to several other Maine groups, Forbes reported last week.