Environmental Issues in Pacific Northwest Forest Management (2000) / Chapter Skim
Currently Skimming:
3 Old-Growth Forests
3 Old-Growth Forests
Pages 44-72
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 44... ...
Variations among forest types are described with respect to those attributes, as wed as variations in the age at which forests acquire particular characteristics after disturbance. The characteristics impart several unique ecological features of old-growth forests, such as complexity and high biodiversity, low susceptibility to disturbance, and mesic microclimate.
|
From page 45... ...
However, because of intermittent fires, shade-tolerant species rarely replace Douglas-fir altogether (Agee 1993~. Similarly, frequent fires maintained dominance by ponderosa pine throughout most of the low- and miclelevation forests in the interior of the Pacific Northwest; hence, forests dominated by shade-tolerant species were a minor component of the region.
|
From page 46... ...
· Number of large, old trees. The minimum density of large, old trees necessary for a stand to qualify as old growth varies from 16 to 50 per O/~-growth forests are forests that have accumu/ated specific characteristics re/atec/ to tree size, canopy structure, snags ant/ Woody debris, and plant associations.
|
From page 48... ...
48 EM Z .= _ o ho fin _ ¢ bOZ ~ In o · - Or, 0 au .C~ ·o be o ~ so == .s o ~5 US o o ~ ~ ~ be= _ o g so =~9 U
|
From page 50... ...
50 x c~ en .o c-)
|
From page 51... ...
In western Oregon and Washington, stands of Douglas-fir that are considered old growth have greater numbers of trees with broken tops, excavated bole cavities, root collar cavities, and bark resinosis than either young or mature stands (Spies and Franklin 1991~. Those characteristics are typical of old trees throughout the region; old grand fir trees, for example, are commonly infected with a heart rot called Indian Paint fungus (Echinodontium tinctorium)
|
From page 52... ...
, a feature common to all types except ponderosa pine, lodgepole pine, and Eastside Douglas-fir. That layering reflects the growth of saplings (mostly shade-tolerant trees)
|
From page 53... ...
To deal with the spatial and temporal variability in succession, Franklin and Spies (1991 b) developed a continuously varying index of old growth based on the following five criteria for naturally established stands in the Oregon coast range, Cascades, and the southern Washington Cascades: · density of large trees (e.g., more than SOcm Dbh)
|
From page 54... ...
54 Cal .~ be o .$ CD a' U)
|
From page 55... ...
55 A. ~ ~ Cat ~ ~ ~ o o o o Go o CO Cat di _ Dot _ Dot ~ Dot ~ ~ ~ ~ ~ U U U U Cat U U U , ~ ,4 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ .~ ~ ~ ~ ~ .
|
From page 58... ...
1997~. Historic reconstructions performed to date, covering a wide area of western Oregon including the Cascade, Siskiyou, ancE Coast Range mountains, have consistently found oldgrowth stands consisted of multiple age classes of overstory trees spanning many tens of decades rather than a single age class (Franklin and Hemstrom 1981; Tappeiner et al.
|
From page 59... ...
For example, pileated woodpeckers, keystone species that excavate cavities used by numerous other bird and mammal species, prefer to roost in large grand fir trees extensively decayed by Indian paint fungus (Bull et al.
|
From page 60... ...
1997) Such techniques attempt to mimic natural disturbances by preserving legacies such as decaying logs and accumulations of soil organic matter (Franklin 1993a)
|
From page 62... ...
that were "closely associated" with old-growth stands in the range of the northern spotted owl, along with 99 invertebrate species and Ill vascular plant species. In his analysis of forests in western Oregon and Washington, Harris (1984)
|
From page 63... ...
Conifers become re-established after populations of insects and pathogens have been reduced because they have so few conifer hosts (Goheen and Hansen 1 993~. The pines, western larch, western red cedar, Engelmann spruce, and western hemlock have higher tree mortality associated with root disease in early stages of stand development (younger than 30 years)
|
From page 64... ...
, and provide organic matter and nutrients that are tapped by mycorrhizae and roots penetrating wood from surrounding plants (Harmon et al. 1986; Schowalter et al.1992~.
|
From page 65... ...
Insects and pathogens are instrumental in directing succession Outgrowth forests are more resistant to crown fires than are through their selection of younger forests.... plant species.
|
From page 66... ...
. Those salmonid species cto not obligately require old-growth forests for survival, but they dicI evolve across a geographic range that closely overlaps that of the Northwestern coniferous forests.
|
From page 67... ...
, the geographic area (e.g., states, Eastside forests, or Westside forests) , land-use types (e.g., forest lands only or combinations of forest, agricultural, residential, and urban lands)
|
From page 68... ...
Rainer Public forest land 65% and Franklin (represents National Park only 1982 historical) region west of the Cascades crest, inferred largely from fire histories, range from 5.6 million ha to nearly ~ million ha, or 54-70% of the commercial forest area (Andrews and Cowlin 1940; Franklin and Spies 1984; Norse 1990; Booth 1994~.
|
From page 69... ...
Thus, by the 1930s, despite extensive logging, 68% of commercial forest land in western Oregon and Washington remained in what FEMAT (1993) classified as "late-successional/old-growth" (stands 80 years of age or older)
|
From page 70... ...
Nearly twothirds of Eastside forest lands covered by the 1936 survey were dominated by ponderosa pine, which, even after a period of heavy cubing that began in the early 1920s, was still mostly old-growth. If adjustments are made for logging before 1936, the original low-and midelevation ponderosa pine forests were nearly 90% old growth.
|
From page 71... ...
In contrast, forest types in northeastern Washington and northern Idaho are unlike other Eastside forests, having higher proportions of Douglas-fir and a representation of species such as western hemlock and western red cedar that are more typical of Westside forests. Historically, northeastern Washington and northern Idaho had extensive stands of western white pine that were probably mostly old growth.
|
From page 72... ...
SUMMARY Because the ecological characteristics of old-growth forests vary from one forest to another, no single definition of old growth is appropriate. However, as knowledge has progressed, various indexes of successional development have been developed to characterize forests.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.