This root illustration shows the variation in root system length and complexity for several common prairie species. Download. Credit: U.S. Environmental Protection Agency.
Biologists at Neal Smith National Wildlife Refuge in south-central Iowa have been studying carbon sequestration on the prairie for more than 15 years. Their research has been the springboard for a national research effort which is based on the idea that grasslands have the capacity to store large amounts of carbon.
The ability to store carbon is a valuable ecological service in today’s changing climate. Carbon, which is emitted both naturally and by human activities such as burning coal to create electricity, is a greenhouse gas that is increasing in the Earth’s atmosphere. Reports from the International Panel on Climate Change, a group of more than 2,000 climate scientists from around the world, say increased greenhouse gases are causing global warming, which is leading to sea level rise, higher temperatures, and altered rain patterns.
Most of the prairie’s carbon sequestration happens below ground, where prairie roots can dig into the soil to depths up to 15 feet and more. Prairies can store much more carbon below ground than a forest can store above ground, according to Dr. Cynthia A. Cambardella, a soil scientist with the U.S. Department of Agriculture’s Agricultural Research Service National Laboratory for Agriculture and the Environment.
To quantify this information, Cambardella and a team of research scientists collected soil cores to a depth of four feet from each of 19 reconstructed prairies ranging in age from one to 17 years within the Neal Smith Refuge in May of 2000, 2005, and 2010.
“We wanted to better understand the carbon storage capabilities of reconstructed prairie on former cropland,” Cambardella said.
The team sought to define the relationship between a prairie’s age and the amount of carbon stored in its soil. They used a method called chronosequence -- a sequence of related soils that differ from one another in certain properties primarily as a result of time.
They found a consistent, positive relationship between prairie age and the amount of biologically-active carbon in the near-surface soil. Biologically-active carbon is made up of fresh inputs of carbon from growing prairie plants. Older prairies had more biologically-active carbon than younger prairies. The team also found that prairie age was not consistently related to the total amount of carbon stored in the soil at any depth, Cambardella said.
This information helped shape the national sampling plan now developing across federal lands on Land Management and Research Demonstration sites in seven types of ecosystems, where researchers are studying the potential for carbon sequestration. The information highlights the importance of on-the-ground soil sampling to estimate that potential.
The goal of the national effort is to produce comparable results from carbon sequestration studies on Service land among several types of ecosystems, in order to quantify the amount of carbon stored on federal lands.
What is Carbon Sequestration?
Carbon sequestration is the ability to contain, store or hold carbon through time. Living plants convert and store atmospheric carbon in their roots, stems, leaves, and wood. When a root, stem or leaf dies, microorganisms that live in the soil convert the plant carbon into soil carbon. In undisturbed plant communities, the carbon remains sequestered in soil for thousands of years. Disturbing the plants and soil can release a large amount of that stored carbon to the atmosphere.
Dr. Patricia Heglund, Chief of the Division of Biological Resources and Regional Refuge Biologist for the Service’s Midwest Region, said “Industrialized society does a lot of things that put carbon in the air and our federal lands are one place where we can potentially offset increasing atmospheric carbon through our land management practices. Not only are federal lands a benefit to fish and wildlife and to the American people for recreational opportunities, these areas are doing favorable things for the environment, such as keeping harmful greenhouse gases out of the atmosphere.”
The Service established a national Biological Carbon Sequestration Working Group to focus on quantifying the benefits of federally managed open spaces beyond that of recreation and habitat. They are in the process of assessing the carbon stores and sequestration potential across ecosystems on Refuge lands across the nation.
The Iowa Climage Report
In 2010, the Iowa Climate Change Impacts Committee submitted a report to the Governor and the Iowa General Assembly that included consequences for Iowa’s flora and fauna, as well as policy recommendations. Download the file here.
Author: Tina Shaw, USFWS, 612-713-5331, firstname.lastname@example.org
Contacts: Chuck Traxler, USFWS, 612-713-5313, email@example.com
Climate Change Impact
Understanding how effective prairies and other ecosystems are at sequestering carbon.