Evaluation of simulated acid precipitation effects on forest microcosms. Final report
Microcosms were treated for a 30-month period with simulated precipitation acidified to four pH levels (5.7, 4.5, 4.0, and 3.5) to evaluate the impact of acid precipitation on foliar leaching, plant nutrient content, soil leaching, soil nutrient content, and litter decomposition. Direct effects of acid precipitation on diameter growth, bud break, leaf senescence, chlorophyll content, stomatal size, stomatal density, photosynthesis, respiration, transpiration, and cuticle erosion were evaluated on tulip poplar, white oak, and Virginia pine seedlings growing as mixed stands in the microcosms. None of the plant physiological or morphological parameters evaluated responded in a statistically significant manner as a result of treatment. A significant treatment canopy interaction was observed in the form of a 60 percent increase in calcium input in throughfall in response to the pH 3.5 treatment. Foliar nutrient content did not change in response to treatment nor did field measurements of decomposer activity. Soil analysis indicated a significantly lower concentration of exchangeable calcium and magnesium in the top 3.5 cm of the mineral soil in association with the pH 3.5 treatment. Soil leachate concentrations exhibited significant increases at both the 25 and 50 cm depths. However, at the 100 cm depth no significant response in concentration or elemental loss from the system was observed. Laboratory respiration measurements indicated a small, but statistically significant reduction in decomposer activity in the lower litter (02) horizon. This reduction was masked in the field measurements of decomposer activity due to the relatively small contribution of the 02 to total soil respiration. 38 references, 12 figures, 18 tables.
- Research Organization:
- Tennessee Valley Authority, Muscle Shoals, AL (USA). Div. of Air and Water Resources
- OSTI ID:
- 6827908
- Report Number(s):
- EPRI-EA-3500; ON: TI84920329
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID RAIN
ALKALI METALS
ALKALINE EARTH METALS
AMMONIA
ATMOSPHERIC PRECIPITATIONS
BIOLOGICAL EFFECTS
BIOLOGICAL MATERIALS
BUDS
CALCIUM
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CHLOROPHYLL
CONIFERS
DECOMPOSITION
DISSOLUTION
ELEMENTS
FOREST LITTER
FORESTS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
LEACHING
LEAVES
MAGNESIUM
MATERIALS
METALS
MICROCOSMS
NITRATES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NUTRIENTS
OAKS
OPENINGS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PINES
PLANTS
PORPHYRINS
POTASSIUM
RAIN
SEPARATION PROCESSES
SIMULATION
SOILS
STOMATA
SULFATES
SULFUR COMPOUNDS
SYNTHESIS
TRANSPIRATION
TREES