What area of the world has had the most of it's flora/fauna destroyed?

Let me explain a little. I know that, historically, when humans land on islands, SEVERAL native species soon become extinct, while many of the remaining are severly reduced (Guam, Hawaii, Reunion, New Zealand, you name it). I was just wondering if there are an estimates out there to show which area (doesn't have to be an island, I just figured it was most likely) has had the highest percent of it's native flora and fauna destroyed, not just with extinctions, but also with general population decline.