PARENT SESSION
Monday, August 7, 5:00-6:30 pm
Poster Session 4 - Soil, mycorrhizal, and microbial ecology
Exhibit Hall, Ballroom Level, Cook Convention Center
Temperature sensitivity of soil organic matter fractions.
Haddix, Michelle*,1, Steinweg, Jessica1, Conant, Richard1, Paul, Eldor1, 1 Colorado State University, Fort Collins, CO
ABSTRACT- Soil organic matter (SOM) acts as a reservoir that contains twice as much carbon as the atmosphere. Temperature is a controlling factor in this reservoir’s turnover and because of this the projected climate change may have a considerable effect on SOM stocks. SOM is composed of heterogeneous materials with varying turnover times and there has been considerable debate about the effect of increased temperature on the decomposition rate of these different SOM fractions. The purpose of this research was to understand how these different fractions respond to increased temperature. Our research utilized soil incubations, land use change, and shifts in plant-derived13C signatures to alter the balance of labile versus resistant soil C on twelve soils at six different locations across a latitudinal gradient from Canada to Brazil. By examining long-term incubation-induced soil C depletion on soils at different temperatures, temperature increases on individual samples at varying times during the incubation, and soil physical and chemical fractionation, we were able to quantify and better understand the temperature sensitivities of the soil fractions. Preliminary results of our soil incubation experiment comparing Q10 temperature coefficients calculated from the proportion of soil C respired indicate that the older native organic matter is less temperature sensitive than the more recent introduced vegetation. Along with this the older native organic matter temperature sensitivity tends to decline over time. These Q10 results combined with 13C measurements and soil fractionation are being used to interpret temperature effects in different soil and fractions there of.
Key words: soil ecology, temperate grasslands and tropical forests, temperature sensitivity