In 1990, an amendment to the Clean Air Act sought to address the effects of acid rain on the general public. Norton says while the impacts on public health were measurably positive, it has been much harder to determine the ecological impacts without long-term studies.
The water chemistry of the reference watershed in East Bear has seen some recovery, especially in sulfate concentration related to the decrease in sulfur emissions to the atmosphere. That recovery, however, is not as great as projected, and current UMaine research is contributing to understanding the complexity of ecological recovery.
A short study also wouldn’t allow researchers to see the implications of a recovery from random, unpredictable events for which there is no adequate model based on ecosystem processes, such as the recent, relatively warm winter or the ice storm of January 1998.
The ice storm, it turns out, had a dramatic effect on the biogeochemistry of Bear Brook. At the time, the impacts appeared minor, but researchers found that the loss of foliage allowed increased sunlight to reach the forest floor, even for a short period of time, causing a blip in the rates of nutrient cycling and changes to the streams that lasted three or four years.
“Had we come along the day before the ice storm and decided to do a year-long study to tell us how the ecosystem functions, we would have gotten it wrong,” Fernandez says. “At that point, we were really watching the variability in ecosystem behavior that was laid over the long-term trend, and without the long-term trend, we wouldn’t have known how to interpret what we were seeing.
“Without the long-term record, you can’t understand events. We can also see that the response to treatments and the effects of changes in the environment on sulfur, calcium, nitrogen and phosphorus would not be discernible with a three- to five-year study.
“You can define short-term responses, but that’s not what happens 10 to 20 years later. That’s what this kind of research allows us to understand.”