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    Author(s): Valerie Rapp
    Date: 2003
    Source: Science Update 4. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 12 p
    Publication Series: Science Update
    Station: Pacific Northwest Research Station
    PDF: View PDF  (2.0 MB)


    Not all forests with old trees are scientifically defined as old growth. Among those that are, the variations are so striking that multiple definitions of old-growth forests are needed, even when the discussion is restricted to Pacific coast old-growth forests from southwestern Oregon to southwestern British Columbia.

    Scientists understand the basic structural features of old-growth forests and have learned much about habitat use of forests by spotted owls and other species. Less known, however, are the character and development of the live and dead trees and other plants. We are learning much about the structural complexity of these forests and how it leads to ecological complexity—which makes possible their famous biodiversity. For example, we are gaining new insights into canopy complexity in old-growth forests.

    Old-growth forests are not places undisturbed by nature for many centuries. Today’s old-growth forests developed along multiple pathways with many low-severity and some high-severity disturbances along the way. And, scientists are learning, the journey matters—old-growth ecosystems contribute to ecological diversity through every stage of forest development. Heterogeneity in the pathways to oldgrowth forests accounts for many of the differences among old-growth forests.

    Complexity does not mean chaos or a lack of pattern. Scientists from the Pacific Northwest (PNW) Research Station, along with scientists and students from universities, see some common elements and themes in the many pathways. The new findings suggest we may need to change our strategies for conserving and restoring old-growth ecosystems. As we discover greater complexity in forests than we ever imagined before, we will need to develop greater complexity in our cultural responses to forests as well.

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    Rapp, Valerie. 2003. New findings about old-growth forests. Science Update 4. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 12 p


    Old-growth, forests, new findings

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