Since 1492 Human Civilization has cleared nearly 10 Billion Acres of Trees. We've cut down many more, but many have re-grown. That means we have about 54% less trees and plants on Earth today. The clearing was done mainly by civilization's expansion and fires. Logging and Wood Industries are generally respectful of the forests and replant forest areas they perform logging activities in so that new growth will eventually become wood products (with some noteworthy exceptions). Civilization has also cleared plant life in corresponding amounts.