Coarse woody debris (CWD) is a term used in English-speaking countries for fallen dead trees and the remains of large branches on the ground in forests and in rivers or wetlands. Some prefer the term coarse woody habitat (CWH). A dead standing tree is known as a snag and provides many of the same functions as coarse woody debris. The minimum size required for woody debris to be defined as "coarse" varies by author, ranging from in diameter.