From the book What If? of Randall Munroe aka XKCD's author:

There would be more large animals 1,000 years ago. Today’s disconnected patchwork of northeastern old-growth forests is nearly free of large predators; we have some bears, few wolves and coyotes, and virtually no mountain lions. (Our deer populations, on the other hand, have exploded, thanks in part to the removal of large predators.)

What does disconnected patchwork of forest mean? From my understanding a patchwork is a thing that is composed of different elements, but I don't understand what the patchwork of forest is, and how it looks like when it's disconnected.