"Most models used to estimate global land use change emissions to date do not have the capability to model this nitrogen limitation on plant regrowth following land use change," said Prasanth Meiyappan, a graduate student who is a co-author of the study. "This means, for example, they overestimate regrowth and they underestimate net emissions from the harvest-regrowth cycle in temperate forest plantations."
Jain's team, in collaboration with Joanna House, a researcher at the University of Bristol's Cabot Institute, concluded that by not accounting for nitrogen as a limiting nutrient for plant growth, other models might have underestimated the 1990s carbon emissions from land use change by 70 percent in nontropical regions and by 40 percent globally.
"This gross underestimation has great implications for international policy," House said. "If emissions from land-use change are higher than we thought, or the land sink (regrowth) is more limited, then future emissions cuts would have to be deeper to meet the same mitigation targets."
Next, the researchers are investigating the impacts of other nutrients, such as phosphorus, on the carbon cycle. They also are estimating the carbon stored in the soil, and how much is released or absorbed when the soil is perturbed.
"Soil has great potential to sequester carbon," Jain said. "The question is, how much that's being released is being sequestered in the soil? We have to understand how human behavior is changing our environment and interacting with our ecosystems."
|Contact: Liz Ahlberg|
University of Illinois at Urbana-Champaign