Infrequently burned prairies dominated by <em>Andropogon gerardii</em>

Abstract

Global climate change has been widely attributed to the accumulation of CO₂ in the atmosphere. This global warming is brought on by excess atmospheric carbon dioxide produced by the burning of fossil fuels. However, the burning of biomass does not contribute a net gain in atmospheric CO₂ because this carbon is part of the active carbon cycle, whereas the carbon in fossil fuel emissions originates from the inactive carbon cycle, and is therefore not returned to its fossil fuel state as quickly as it is released. Soil organic matter (SOM) may hold up to four times the carbon of living biomass, giving land with high levels of SOM the potential to act as carbon sinks to counteract global warming. In our study, we sought to determine which prairie grass species accumulated the greatest amount of biomass, which is directly related to the organisms ability to accumulate carbon. We also studied the effects of fire on SOM levels. We found that there is no significant difference in SOM between annually burned and unburned prairie plots. We also found that certain native warm-season (C₄) grasses, particularly A. gerardii, produce significantly larger amounts of both above and belowground biomass than do cool-season (C₃) species. In addition, we have determined that an infrequently burned prairie dominated by A. gerardii, as most native tallgrass prairies are, will act as an effective carbon sink.