Effects of acid rain on forest nutrient status

Technical Report · Thu Aug 01 04:00:00 EDT 1985

OSTI ID:5152922

Johnson, D W; Cole, D W; Kelly, J M; Webb, J W; Richter, D D; Van Miegroet, H

In five forest sites (three in eastern Tennessee and two in western Washington) the effect of natural carbonic acid production on soil leaching was equaled or exceeded by that of atmospheric acid inputs. In a nitrogen-fixing red alder site in Washington, however, internal leaching by nitrification and nitric acid formation far exceeded atmospheric H/sup +/ inputs at any site. All other sites retained NO/sub 3//sup -/, and soil SO/sub 4//sup 2 -/ adsorption reduced the effectiveness of atmospheric H/sub 2/SO/sub 4/ inputs on soil leaching in two of the Tennessee sites and in the Washington red alder site. The very high natural leaching rates in the red alder stand have significantly acidified, and continue to acidify, that soil. At all other sites, base cation loss rates were not large enough to rapidly deplete soil exchangeable cation reserves, and no long-term significant soil acidification by acid deposition is foreseen. Furthermore, scarce or potentially limiting cations (such as Ca/sup 2 +/ in one of the Tennessee sites) are being conserved despite accelerated leaching rates. Atmospheric sulfur inputs exceeded forest sulfur requirement in all five sites. Excess sulfur accumulated to a minor extent as SO/sub 4//sup 2 -/ in vegetation, but soils were the major repository for excess SO/sub 4//sup 2 -/. The greatly enhanced nitrogen status of the red alder stand appeared to have lowered SO/sub 4//sup 2 -/ in both vegetation and soils at that site as compared to the adjacent nitrogen-poor Douglas-fir site. Decomposer invertebrates appeared to be affected negatively by unrealistically large applications of SO/sub 4//sup 2 -/, either as KHSO/sub 4/ or K/sub 2/SO/sub 4/. Forest floor buffering prevented large changes in pH with acid SO/sub 4//sup 2 -/ treatments. Results indicate that effects of acid deposition on decomposer invertebrates are unlikely except at input levels much higher than ambient. 32 refs., 9 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5152922
• Report Number(s): ORNL/TM-9729; ON: DE85018120
• Country of Publication: United States
• Language: English

Related Subjects

500200 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
510200* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID RAIN
ACIDIFICATION
AIR POLLUTION
ATMOSPHERIC PRECIPITATIONS
BIOLOGICAL MATERIALS
CARBON COMPOUNDS
CARBONATES
CATIONS
CHARGED PARTICLES
DEPOSITION
DISSOLUTION
ENVIRONMENTAL EFFECTS
FOREST LITTER
FORESTS
IONS
LEACHING
MATERIALS
MINERAL CYCLING
NAPAP
NITRATES
NITROGEN COMPOUNDS
NUTRIENTS
OXYGEN COMPOUNDS
POLLUTION
RAIN
SEPARATION PROCESSES
SOILS
SULFATES
SULFUR COMPOUNDS