In forest

Forest

A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

 ecology

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

, a snag refers to a standing, partly or completely dead tree

Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

, often missing a top or most of the smaller branches. In freshwater ecology

Limnology

Limnology , also called freshwater science, is the study of inland waters. It is often regarded as a division of ecology or environmental science. It covers the biological, chemical, physical, geological, and other attributes of all inland waters...

 it refers to trees, branches, and other pieces of naturally occurring wood found sunken in rivers and streams; it is also known as coarse woody debris

Coarse woody debris

Coarse woody debris is a term used in English-speaking countries for fallen dead trees and the remains of large branches on the ground in forests. Some prefer the term coarse woody habitat . A dead standing tree is known as a snag and provides many of the same functions as coarse woody debris...

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Standing snags provide critical habitat for many species, e.g., woodpeckers that feed on insects dwelling in decomposing wood.