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Grasslands won't help buffer climate change as carbon dioxide levels rise
August 09, 2005Because grasslands and forests operate in complex feedback loops with both the atmosphere and soil, understanding how ecosystems respond to global changes in climate and element cycling is critical to predicting the range of global environmental changes-and attendant ecosystem responses-likely to occur. In a new study in the premier open access journal PLoS Biology Jeffrey Dukes, Christopher Field, and colleagues treated grassland plots to every possible combination of current or increased levels of four environmental factors-CO2, temperature, precipitation, and nitrogen influx-to simulate likely regional changes over the next 100 years. The results of their long-term experiment reveal that California grasslands, and ecosystems that respond similarly, are not likely to help buffer the rate of climate change by acting as a carbon "sink"-slowing the rise of CO2 levels by storing more carbon in new growth.
The experiments were part of the Jasper Ridge Global Change Experiment (JRGCE), which started on Stanford's 1,200-acre biological preserve in 1997. Since 1998, this grassland ecosystem has been outfitted with an ecologist's version of a microclimate controller (complete with CO2 pumps, heaters, and irrigation tubing) and subjected to experimentally controlled atmospheric, climatic, and nutrient conditions. (This study examines the experiment's first five years.) To quantify the grassland response to these treatments, the authors estimated net primary production, or NPP (the amount of carbon left over after cellular respiration) by measuring shoot and root growth in 36 circular plots scattered across roughly two acres. The strongest effects on grassland production came from elevated levels of nitrogen (which typically reaches a fertilization limit). Elevated temperature, rainfall, and, surprisingly, CO2, had minimal impacts. These results suggest that increasing concentrations of atmospheric CO2 are not likely to increase growth of the roots and leaves of plants in this grassland. Why not? One possibility involves phosphorus. High levels of CO2 and nitrogen can reduce phosphorus concentrations or limit its uptake in these plants. Ongoing JRGCE experiments are exploring how this and other factors-such as grazing or shifts in seasonal events-might limit the growth effects of CO2.
It's thought that ocean and terrestrial ecosystems have stored nearly half the carbon emissions produced by humans since the industrial revolution. If it turns out that other natural systems also fail to sequester as much carbon as scientists once thought, atmospheric CO2 concentrations will rise even faster than expected-with serious implications for future climate change.
Public Library of Science
Public Library of Science
Grasslands Current Events and Grasslands News RSS'Arid aquaculture' among livelihoods promoted to relieve worsening pressure on world's drylands
"Arid aquaculture" using ponds filled with salty, undrinkable water for fish production is one of several options experts have proven to be an effective potential alternative livelihood for people living in desertified parts of the world's expanding drylands.
Fertilizers - a growing threat to sea life
New study on landscape around Chesapeake Bay says imbalance in nitrogen cycle is damaging water quality and fish populations.
Current mass extinction spurs major study of which plants to save
The Earth is in the midst of the sixth mass extinction of both plants and animals, with nearly 50 percent of all species disappearing, scientists say.
Oklahoma researchers support biodiversity in biofuels production
U.S. and European mandates for subsidies of cellulosic ethanol production and use have uncertain environmental consequences according to an international group of scientists which includes researchers from the University of Oklahoma and Oklahoma State University.
Black-footed ferrets sired by males that died 8 years ago
Two black-footed ferrets at the Smithsonian's National Zoo have each given birth to a kit that was sired by males who died in 1999 and 2000
Evaluating ecosystem services
Environmental conservation efforts have traditionally focused on protecting individual species or natural resources. Scientists are discovering, however, that preserving the benefits that whole ecosystems provide to people is more economically and environmentally valuable. At the Annual Meeting of the Ecological Society of America (ESA), ecologists will explore the application of ecosystem services approaches to conservation.
Ouch! Taking a Shot at Plague: Vaccine Offers Hope for Endangered Ferrets in Plague Outbreak
Endangered black-footed ferrets, like children, aren't exactly lining up to be stuck with a vaccine, but in an effort to help control an extensive outbreak of plague in South Dakota, some of the ferrets are getting dosed with a vaccine given by biologists.
New study finds that some plants can adapt to widespread climate change
While many plant species move to a new location or go extinct as a result of climate change, grasslands clinging to a steep, rocky dale-side in Northern England seem to defy the odds and adapt to long-term changes in temperature and rainfall.
Plan to conserve forests may be detrimental to other ecosystems
Conserving biodiversity must be considered when developing plans to reduce greenhouse gas emissions from deforestation, researchers warn in today's edition of Science.
Study of guanacos launched in Chile
The Wildlife Conservation Society has launched a study in Chile's Karukinka reserve on Tierra del Fuego to help protect the guanaco - a wild cousin of the llama that once roamed in vast herds from the Andean Plateau to the steppes of Patagonia.
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