Here's a very nifty graphic that shows the spread of agriculture and the increasing intensity of agricultural land use over the last 300 years. If you get your eye on Lake Michigan in North America watch as the prairie to the south and west gradually turns yellow as it disappears. Here in Lincolnland less than 1% of the original prairie has survived thanks to John Deere. As human demands have increased, it has come at the cost of natural communities. Nothing mysterious at all. HT to the Scientist Gardener.