People have been pushing into forestlands for thousands of years, but during the last century, scientists say, the rate of global forest reduction has reached alarming levels. About 50 million acres of forest are cleared every year. Much of Europe’s original forests are gone. The forests of North America, which once dominated the landscape, have shrunk by almost 40% in the last two centuries to make room for people and meet the demand for lumber and paper. Not only have many of the animals that depend on these ecosystems disappeared, but various species of trees have also been depleted. Timber farms on land that once sustained natural forests have little of the biodiversity of the original forests, with pesticides and other chemicals allowing the land to support only a few kinds of life.