Title: Carbon storage and accumulation in United States forest ecosystems
Identifier: CAT93989847 (find matches)
Year: 1992 (1990s)
Authors: Birdsey, Richard A; United States. Forest Service
Subjects: Carbon cycle (Biogeochemistry) United States; Plants Effect of carbon on; Trees Climatic factors United States; Forest ecology United States
Publisher: (Washington, D. C. ?) : U. S. Dept. of Agriculture, Forest Service
Contributing Library: U.S. Department of Agriculture, National Agricultural Library
Digitizing Sponsor: U.S. Department of Agriculture, National Agricultural Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
Forest type Douglas-fir Spruce-fir Lodgepole pine Maple-beech-birch Oak-hickory Loblolly (natural) Loblolly (planted) Pinyon-juniper
Text Appearing After Image:
Soil 100 150 Thousand pounds/acre I Forest Floor 200 Trees 250 Figure 6—Average carbon storage in the soil, forest floor, and trees for selected forest types. Changes in carbon storage in the forest ecosystem are primarily related to changes in carbon storage in live trees. The rate of accumulation of carbon in live trees is greatest in the forest areas where trees typically have the fastest volume growth, the Southeast and the Pacific Northwest (fig. 7). On average, live trees are accumulating carbon at a rate of 1,252 pounds per acre per year (0.14 kg/m2/yr), a rate of increase of 2.7 percent of the amount stored in live trees. The accumulation of carbon in live and dead trees totals 508 million tons (461 million metric tons) per year, while the total removal of tree carbon from U.S. forests resulting from timber harvest, landclearing, and fuelwood use amounts to 391 million tons (355 million metric tons, fig. 8). A compari- son of accumulation and removal suggests that U.S. forest trees are storing additional carbon at a rate of 117 million tons (106 million metric tons) per year. This is equivalent to about 9 percent of the annual U.S. emission of carbon to the atmosphere (1.2 billion metric tons) per year (Boden and others 1990). Trees dying annually because of insects, diseases, fire, and weather contain about 83 million tons (75 million metric tons) of carbon. Only a portion of tree mortality was deducted from accumulation in the comparison of accumulation and remov-al since much of the carbon remains in the forest ecosystem for some time as standing dead trees, coarse woody debris on the forest floor, and eventually other organic matter in the forest ecosystem. There are significant regional differences in relative and total estimates of carbon accumulation, removal, and mortality. For softwoods, Pacific coast forests are accumulating the most carbon annually, followed by the Southeast, South Central, and Rocky Mountain regions (fig. 9). Because softwood removal is so low relative to growth in the Rocky Mountains, the increase in carbon storage in softwood species is much greater there than elsewhere. Mortality is the highest in the Rocky Mountains and on the Pacific coast. In the South Central region, tree removal is causing a net loss of carbon storage in softwood trees. Most of the hardwood resource in located in the Eastern United States. The Northeast has the largest excess of hardwood carbon accumulation over removal, but there are also large increases in hardwood carbon storage occurring in the Southeast and on the Pacific coast (fig. 10). 6

Note About Images