Research Project Summary Information
Assessing the Sensitivity of New York Forests to Calcium Depletion(ST8649-1)
SUNY Research Foundation
The degree to which acid rain threatens forest health and productivity depends in part on the ability of soils to supply calcium (Ca) and other base cations for forest growth. Predictions of Ca depletion have been based on the assumption that only the salt-exchangeable Ca pool is available to plants; the weathering of Ca from parent materials has been believed to be too slow to play a role in mediating the acidifying effects of air pollution on soils. Because of these assumptions, the role of readily weathered Ca-bearing trace minerals, such as apatite and calcite, have been overlooked in assessments of Ca depletion from acid rain. Carbon (C) storage in forest soils is also of increasing interest because of the need to account for C storage in soils when using forests to offset emissions of CO2. Recent work linking changes in extractable cations to soil C and N content raises the possibility that changes in soil Ca pools could, in turn, influence soil C and N storage.
Twenty sites will be selected in New York State for sampling based on bedrock geology and the distribution of soil types. Basing the sampling scheme on soil mapping units will provide a basis for extrapolation in future efforts to map the distribution of Ca sources in parent materials. C and N in the soil samples collected will also be analyzed to study relationships between soil Ca, C, and N. Additional soil samples collected in sites where Ca was added in liming experiments 14 to 41 years ago shall be analyzed for C and N as well, to test whether patterns observed at the landscape level are likely to predict changes over time with continued atmospheric deposition of N and leaching of Ca. Twenty additional sites will be selected for sampling, using the same geological and soil categories used above but adding a diversity of tree species and forest types. The Contractor will compare how the same forest- types fare on soils formed from contrasting parent materials, and also how different tree species or forest types differ in the Ca sources they access from the same substrate.
This project data will be important to the development of sound policies for the management and protection of New York's forest resources impacted by acid deposition. It will provide a more accurate assessment of New York State forests potentially adversely effected by the depletion of calcium and other exchangeable cations.
The findings suggest that, to a first order, bedrock controls the spatial distribution of apatite and carbonate located in the glacial till in the northeastern USA, as well as the concentration of exchangeable Ca in overlying horizons. The occurrence of carbonates or apatite in parent material contributes to the pool of readily weathered Ca, which mitigates the threat of Ca depletion from repeated forest harvest or acid rain. Investigators compared limed and un-limed plots at four forested sites treated 14-41 years earlier and found 5-75% more organic matter and N in the limed plots, suggesting that soils may be storing more C and N over time as they acidify. Finally, the investigators measured the concentration of Ca and other elements in leaf litter at the same sites studied in the first phase of the project. Birch and maple species showed the most response to soil variation in Ca; spruce and fir had low Ca across all sites. More research is needed to determine the relative ability of different tree species to access Ca from different soil sources.
SUNY Research Foundation
Empire State Plaza Concourse Level Rm 106
Albany, NY 12224
SUNY College of Environmental Science an
Environmental Monitoring & Research
NYSERDA Contact Information
R&D - Environment & Energy Res