Snag (ecology)

In freshwater ecology 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.

These organisms and their consumers, along with the structural complexity of cavities, hollows, and broken tops make snags important habitat for birds, bats, and small mammals, which in turn feed larger mammalian predators.

A snag undergoes a series of changes from the time the tree dies until final collapse, and each stage in the decay process has particular value to certain wildlife species.

In freshwater ecology in Australia and the United States, the term snag is used to refer to the trees, branches and other pieces of naturally occurring wood found in a sunken form in rivers and streams.

Such snags have been identified as being critical for shelter and as spawning sites for fish, and are one of the few hard substrates available for biofilm growth supporting aquatic invertebrates in lowland rivers flowing through alluvial flood plains.

Snags are important as sites for biofilm growth and for shelter and feeding of aquatic invertebrates in both lowland and upland rivers and streams.

Large tracts of the lowland reaches of the Murray-Darling system are now devoid of the snags that native fish like Murray cod require for shelter and breeding.

[12] In Scandinavia and Finland, snags, invariably pine trees, known in Finnish as kelo and in Swedish as torraka, are collected for the production of different objects, from furniture to entire log houses.