The effect of charcoal on decomposition in tallgrass prairies

Background/Question/Methods

The issue of climate change has highlighted many important ecosystem services that are not yet well understood.  One major component of global climate change is the increase in CO₂ levels in the atmosphere.  An ecosystem process that mitigates this effect is the storage of carbon in the soil.  Approximately 75% of the carbon stored in terrestrial ecosystems is found in the soil rather than the living biomass (Malhi et. al 2002).  The structure of black carbon or charcoal makes it an ideal form of long term storage of the CO₂ that is captured by plants.  A unique feature of charcoal is its porosity.  This porosity allows the charcoal to have a large surface area, making it a hospitable environment for soil microbes and fungi (Tenenbaum 2009). This interaction could result in greater decomposition rates. I hypothesized that the addition of charcoal to tallgrass prairie soils would increase the rate of decomposition and which can potentially increase the amount of recalcitrant carbon stored in the soil.  I tested this by obtaining 90 soil samples from thirty remnant and restored prairies.  The samples were incubated for three months and analyzed using change in total carbon and total nitrogen as a measure of decomposition.

Results/Conclusions

The analysis of a subset of data indicates that the addition of charcoal to tallgrass prairie soils decreases the amount of carbon lost in the system.  This is contrary to the hypothesis that the addition of charcoal would increase the rates of decomposition.  The recalcitrant nature of the charcoal could be in fact increasing the carbon storing capacity of the soil.  Further analysis of the results needs to be performed in order to make a definitive conclusion.