Effects of acid deposition and liming mitigation Park, NY

Background/Question/Methods   Acid rain affects a number of ecological processes, including the depletion of soil calcium which has a cascading effect on soil processes, aboveground net primary productivity, and invertebrate density and diversity. This study investigated how acid deposition and liming mitigation affect belowground soil characteristics and processes in the Adirondack forest around Old Forge, NY. We hypothesized that the addition of calcium in the form of crushed limestone (minimum Ca content 30%) would increase pH, Ca2+concentrations, bulk density, N-mineralization rates, available phosphorus concentrations, microbial and total N and P concentrations, and CO2 flux. In a factorial experiment, four paired plots, one limed and one control, were divided by four separate streams. The liming treatment (10 metric t ha-1 total) occurred during autumn of 2005 and spring and autumn 2006. In the summer of 2009, volumetric samples of the organic (O) and A soil horizons were collected from three subplots from each paired plot (n = 48). Soils were homogenized, processed and analyzed.

Results/Conclusions   We found significant effects of liming on many soil characteristics and processes, including pH, N-mineralization rates, Ca2+concentrations, and available phosphorus concentrations, all of which increased. However, we found little to no effects on bulk density or gravimetric water content between treatments. Data on bulk N, P and C and cation exchange capacity are still in process. Preliminary results indicate that liming has a significant and positive effect on soil processes which should result in measurable increases in aboveground net primary productivity and invertebrate biomass.