Presentation Title

Temperature sensitivity of soil carbon

Faculty Mentor

Cinzia Fissore, Assistant Professor, Whittier College

Start Date

18-11-2017 12:30 PM

End Date

18-11-2017 1:30 PM

Location

BSC-Ursa Minor 15

Session

Poster 2

Type of Presentation

Poster

Subject Area

behavioral_social_sciences

Abstract

There is large interest in understanding the role of soil carbon (C) under warmer conditions. Specifically, we need to better understand how much carbon could be lost to the atmosphere from soils if the climate warms. Since carbon cycling processes in soils are enzyme-mediated, production of CO2 in soil is temperature sensitive. This aspect of soil respiration was investigated by exposing soils to varying temperatures. In order to test this, 20 grams of 3 different soil types were put into separate jars. Each set of the 3 soils was incubated at 5ºC and 30ºC for 23 days. Every week CO2 concentration was measured for each sample; the samples were also weighed and watered to maintain constant moisture. Initial C content in each soil was also measured. Our incubation results indicate that greater soil C loss occurs in soils incubated at higher temperature. Also, at both incubation temperatures, orchard soil had greater soil C loss that the other two soil types. Specifically, orchard soils lost 6% of their original C when incubated at 30ºC and 0.6% of their original C when incubated at 5ºC. While potting soils, which originally had 56% C, had greater instantaneous CO2 respiration, overall they lost less than 1% C. Large instantaneous CO2 emissions from potting soils are due to the high initial C content (56%) compared to the other soil types (1.7% C and 9.7% C in chaparral and orchard soils, respectively). However, because of such large initial C content, overall losses during the 23 days incubation are limited. This can be in part explained by the observation (from a separate, parallel study) that potting soil contains highly recalcitrant forms of C whereas orchard soil contain more labile forms of C, which are known to undergo fast microbial decomposition. Many of the results can be attributed to the activity of the microbes in the soil, which tend to be more active in warm moist environments rather than dry, cooler ones. From the data gathered thus far, it appears that rising global temperatures may account for an increase in soil respiration and consequently CO2 emission, which may contribute to the greenhouse effect. This becomes especially concerning with the rate global climate is increasing, which can result in even more CO2 emissions entering the atmosphere from the soil.

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Nov 18th, 12:30 PM Nov 18th, 1:30 PM

Temperature sensitivity of soil carbon

BSC-Ursa Minor 15

There is large interest in understanding the role of soil carbon (C) under warmer conditions. Specifically, we need to better understand how much carbon could be lost to the atmosphere from soils if the climate warms. Since carbon cycling processes in soils are enzyme-mediated, production of CO2 in soil is temperature sensitive. This aspect of soil respiration was investigated by exposing soils to varying temperatures. In order to test this, 20 grams of 3 different soil types were put into separate jars. Each set of the 3 soils was incubated at 5ºC and 30ºC for 23 days. Every week CO2 concentration was measured for each sample; the samples were also weighed and watered to maintain constant moisture. Initial C content in each soil was also measured. Our incubation results indicate that greater soil C loss occurs in soils incubated at higher temperature. Also, at both incubation temperatures, orchard soil had greater soil C loss that the other two soil types. Specifically, orchard soils lost 6% of their original C when incubated at 30ºC and 0.6% of their original C when incubated at 5ºC. While potting soils, which originally had 56% C, had greater instantaneous CO2 respiration, overall they lost less than 1% C. Large instantaneous CO2 emissions from potting soils are due to the high initial C content (56%) compared to the other soil types (1.7% C and 9.7% C in chaparral and orchard soils, respectively). However, because of such large initial C content, overall losses during the 23 days incubation are limited. This can be in part explained by the observation (from a separate, parallel study) that potting soil contains highly recalcitrant forms of C whereas orchard soil contain more labile forms of C, which are known to undergo fast microbial decomposition. Many of the results can be attributed to the activity of the microbes in the soil, which tend to be more active in warm moist environments rather than dry, cooler ones. From the data gathered thus far, it appears that rising global temperatures may account for an increase in soil respiration and consequently CO2 emission, which may contribute to the greenhouse effect. This becomes especially concerning with the rate global climate is increasing, which can result in even more CO2 emissions entering the atmosphere from the soil.