"To put it in perspective, there is enough nitrogen contained in one inch of the rocks at our study site to completely support the growth of a typical coniferous forest for about 25 years," said Professor Randy Dahlgren, a biogeochemist and a study co-author.
"This nitrogen is released slowly over time and helps to maintain the long-term fertility of many California forests," Dahlgren said. "It is also interesting to consider that the nitrogen in the rocks from our study site originates from the time of the dinosaurs, when plant and animal remains were incorporated into the sediments that eventually formed the rocks."
The UC Davis findings:
The UC Davis study, led by Scott Morford, a graduate student in the Department of Land, Air and Water Resources, focused on measuring the nitrogen in rocks, soils and plants, and found that rocks enriched in nitrogen have a profound effect on the fertility of forests.
Data from the study indicate that the amount of carbon stored in forest soils derived from the nitrogen-rich bedrock was nearly twice that of sites associated with nitrogen-poor rocks in Northern California. Furthermore, the researchers used the inventory of forest growth data from the National Forest Service to determine that this was not just a localized effect. In fact, the productivity of forests growing on nitrogen-rich rock was approximately 50 percent higher than the productivity of forests growing on nitrogen-poor rocks throughout Northern California and into Oregon.
"We were all stunned when the data showed that the nitrogen in the trees was extremely high in forests that were living on the rocks with high nitrogen," said Morford.
To confirm the link between the nitrogen in the trees and that in the surrounding rock, the researchers traced the n
|Contact: Patricia Bailey|
University of California - Davis