<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2009) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> An old - growth forest--also termed primary forest, virgin forest, primeval forest, or late seral forest--is a forest that has attained great age without significant disturbance and thereby exhibits unique ecological features and might be classified as a climax community . Old - growth features include diverse tree - related structures that provide diverse wildlife habitat that increases the biodiversity of the forested ecosystem . The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris . </P> <P> Old - growth forests are valuable for economic reasons and for the ecosystem services they provide . This can be a point of contention when some in the logging industry may desire to cut down the forests to obtain valuable timber, while environmentalists seek to preserve the forests for benefits such as maintenance of biodiversity, water regulation, and nutrient cycling . </P>

Why are forests in alaska and the pacific northwest called old-growth forests
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