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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999

FROM VOLUME 12, NUMBER 4, APRIL 1999

JOURNAL ARTICLES...
SOILS

Item #d99apr6

“Transferring Soils from High- to Low-Elevation Forests Increases Nitrogen Cycling Rates: Climate Change Implications,” S. C. Hart and D. A. Perry,Global Change Biology 5 (1), 23-32 (1999).

Intact soil cores were transferred from a high-elevation, old-growth forest to a forest 800 m lower with a mean annual air temperature 2.4° C higher and a mean annual soil temperature 3.9° C higher. Soil nitrogen mineralization and nitrification more than doubled, and inorganic-nitrogen leaching also increased.

Item #d99apr7

“Changing Sources of Nutrients During Four Million Years of Ecosystem Development,” O. A. Chadwick et al.,Nature 397, 491-497 (1999).

In humid environments, rock-derived nutrients are leached out of the soils, leading to nutrient depletion. However, the productivity of rainforests in Hawaii has remained constant because of nutrient inputs from the atmosphere. Needed cations are supplied by marine aerosols, and phosphorus is supplied by airborne dust that is blown to Hawaii from more than 6000 km away in central Asia.

Item #d99apr8

“Three Decades of Observed Soil Acidification in the Calhoun Experimental Forest: Has Acid Rain Made a Difference?” Daniel Markewitz et al.,Soil Sci. Soc. Am. J. 62 (5), 1428-1439 (1998).

For the past 30 years, the hydrogen-ion budget for the Calhoun Experimental Forest in South Carolina was studied, and the accumulated nutrients, tree-root respiration, and organic acids produced from the breakdown of litter were measured. Acid rain was found to accelerate the acidification of forest soils, stripping the soil of nutrients and minerals and hampering the soil’s ability to buffer trees from toxic substances. Soil acidification was found to increase by 38% at the Calhoun Forest during the observation period. Soil pH decreased by as much as one unit in the top 14 in. of soil and by half a unit in the next 14 in. A decrease in soil sulfate levels over the past decade was also found and was attributed to stricter air-quality standards.