Yellow birch and acid deposition in the Southern Appalachians

USDA Forest Service Forest Health Monitoring, Northern Research Station, and Rocky Mountain Research Station; Equinox Environmental; Great Smoky Mountains National Park

SUMMARY: A reported increase in a number of large dead trees in high elevation maple-beech-birch forests near Grandfather Mountain in North Carolina triggered an air and ground survey that found most of these large (>15 inch dbh, or diameter at breast height) dead trees were yellow birch. Soil samples from one site showed low acidity and calcium, and high aluminum, iron, and toxic elements (lead, zinc, and cooper). A literature search revealed that larger diameter yellow birch trees in the northeast United States had reduced growth, low resistance to insects and pathogens, and high mortality rates on soils where acid deposition had increased acidity and reduced soil calcium. Larger size yellow birch does poorly on soils with low calcium because it cannot move calcium, necessary for growth and response to infections and wounds, from older tissues to new growing tissues.

EFETAC'S ROLE: Eastern Threat Center scientists are leading this project.

STATUS: Ongoing

PROGRESS: In 2007, Eastern Threat Center scientists used regional Forest Inventory and Analysis data to find areas where large yellow birch were located, and conducted a survey of 48 sites in the Southern Appalachian Mountains where 5 or more large (>15 inches), medium (12-15 inches) and smaller (5-12 inch) yellow birch trees were located. Researchers evaluated trees for crown condition and damages; counted number of seedlings and saplings; located associated large black cherry, sugar maple, and red spruce; and collected 3 mineral soil samples and sent them for analysis. In 2008, researchers obtained tree ring growth cores and wound response damage holes from a subset of the 48 plots with yellow birch and black cherry (a tree tolerant of low soil calcium).

Evaluation revealed that soil pH values were relatively low (< 4.5), and aluminum/calcium ratios were high. Sulfur and toxic metals were also elevated at a number of sites. Researchers found consistent relationships between elevation, soil acidity, high aluminum and toxic metals, high damage scores, and low soil calcium. Larger dbh yellow birch trees were found to have the highest damage index scores. Yellow birch seedling and sapling regeneration was absent or poor at many of the 48 sites.

yellow birch damagePictured: Examples of some of the serious damages found on larger diameter yellow birch trees include dead and decayed roots, cankers and conks on lower bole area, and presence of adventitious roots (a tree stress-response). Click to enlarge.

damage indexPictured: Relationship of elevation (X), pH of 0-4 inch mineral soil (Y), and damage index (Z) for all dbh size classes of yellow birch. Highest levels of damage index (yellow to red) were observed at highest elevations and lowest pH values. Click to enlarge.

regenerationPictured: The number of yellow birch seedlings (< 1 inch dbh) and saplings (1 to < 5 inch dbh) found associated with all size classes of yellow birch trees at 48 sites. Note many sites have no seedling or sapling regeneration. High numbers of seedlings were found growing along base of dead and down large yellow birch trees releasing stored calcium into the soil. Click to enlarge.



Amacher, M.A. and C.H. Perry. 2008. Criterion 4. 2010 National Report on Sustainable Forests. In review.

Shortle, W.C. and K.T. Smith. 1988. Aluminum-induced calcium deficiency syndrome in declining red spruce. Science 240(4855):1017-1018.

Stolte, K.W. 2001. Forest Health Monitoring and Forest Inventory and Analysis programs monitor climate change effects in forest ecosystems. Human and Ecological Risk Assessment 7 (5):1297-1316.


Johnny Boggs, Eastern Threat Center Biological Scientist, or 919-549-4060

Updated July 2018

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