Bill Bowman, Cory Cleveland (former INSTAAR, U. of Montana), and colleagues at the Slovak Academy of Science and the U.S. Geological survey have found that vegetation and soils already subjected to long-term acid rain could face even more stress in the form of nitrogen-laden precipitation.
The team studied the response of soils and alpine vegetation in the Tatra Mountains of Slovakia, an area which received high levels of acid precipitation during the Soviet era of industrialization in Eastern Europe. When they subjected vegetation at the research site to an increase in nitrogen similar that that expected to occur in the next several decades, plant growth decreased instead of the typical increase. Under the high soil acidification levels of the Tatra Mountains, important plant nutrients, such as calcium, were lost. Moreover, the increased nitrogen load triggered the release of soluble iron, which inhibits plant growth. In contrast, aluminum decreased, despite it being the usual culprit damaging plants and soil organisms as well as the element dominating the buffering capacity of the soil.
The authors suggest that this site, and potentially others in central Europe, have reached a new and potentially more toxic level of soil acidification in which aluminum release is superseded by iron release into soil water. This acidification level is comparable to those seen in soils exposed to acid mine drainage. Natural recovery is expected to only occur in geologic time, well beyond human time frames.
The team's paper was published in the 2 November issue of Nature Geoscience.