Abstract |
In the investigation, our aim was to determine if acid rain affects soil microbial activity and to identify possible mechanisms of observed effects. A Sierran forest soil (pH 6.4) planted with Ponderosa pine seedlings was exposed to simulated rain (pH 2.0, 3.0, 4.0 and 5.6) with ionic composition reflecting that found in northern California, corresponding to 15 cm of precipitation over a 12-week period. After exposure, the soils were collected in two samples (top 1 cm and 4 to 5 cm), which were assayed separately for respiration and enzyme activies (urease, phosphatase, dehyrogenase, and arylsulfatase). Changes in microbial activity were most significant in surface soils. Only the pH 2.0 input caused inhibition of both respiration and enzyme activities. (Copyright (c) 1983, ASA, CSSA, SSSA.) |