TY - JOUR
T1 - Influence of snow-cover and soil-frost variations on continuously monitored CO 2 flux from agricultural land
AU - Ohkubo, Shinjiro
AU - Iwata, Yukiyoshi
AU - Hirota, Tomoyoshi
N1 - Funding Information:
We thank Dr. Manabu Nemoto for his technical support and field assistance, Mr. Yuji Kato, Mr. Syuji Yanagiya, Mr. Makoto Yamazaki, Mr. Shinichi Saito, and Mr. Kunio Nishioka for their assistance in field operations, and Dr. Osamu Nagata, Dr. Nobuhisa Koga and Dr. Tomotsugu Yazaki for helpful suggestions. Constructive comments by anonymous reviewers helped us to improve the manuscript. This research was supported by Environment Research and Technology Development Fund (A-0807) of the Ministry of the Environment, Japan. Shinjiro Ohkubo was supported by a Research Fellowship for Young Scientists from the Japan Society for the Promotion of Science (23-3318).
PY - 2012/11/15
Y1 - 2012/11/15
N2 - Changes in cryospheric snow accumulation, snowmelt, and soil freezing and thawing might influence the ground-surface CO 2 flux and cumulative winter CO 2 flux from agricultural land. We continuously observed CO 2 flux using automatically closing chambers at an untreated control plot and a plot with snow removal in northern Japan. The CO 2 in soil pores at 10-cm depth increased by 6.5ppmvday -1 as soil began to freeze, but it increased dramatically (to 49ppmvday -1) after snowmelt water infiltrated the soil and froze. The soil-frost layer constrained gas diffusion into the air, and the barrier strengthened as the frozen snowmelt water decreased the air volume in soil pores. Leached gas CO 2 from the freezing snowmelt water also increased gas CO 2 concentration in soil. As the soil thawed, the CO 2 concentration decreased drastically, at 790ppmvday -1. However, these changes had little effect on CO 2 flux. The soil CO 2 concentration remained stable after snow cover reached 30cm in the control plot. Low CO 2 flux in both plots occurred during the winter. No clear relation was found between CO 2 flux and snow depth or soil-frost depth because of the small CO 2 source at this site. We also considered how the presence of the chamber influenced soil temperatures and water contents. During the snow-free season, the chamber mitigated diurnal changes in soil temperature. The daily average soil temperature differed from that in the natural state by -1.7°C to 6.3°C. This fluctuation of temperature corresponded to the fluctuation of CO 2 flux, which ranged from 91% to 143% of the CO 2 flux in the natural state based on the temperature-response equations. The chamber had little influence on the soil temperature during the snow-cover period, and did not influence soil water content throughout the study period. Cumulative winter CO 2 emissions were 17.2gCm -2 (over 143 days) in the control plot and 13.4gCm -2 (over 151 days) in the treated plot (10.0 and 7.5% of annual accumulation, respectively).
AB - Changes in cryospheric snow accumulation, snowmelt, and soil freezing and thawing might influence the ground-surface CO 2 flux and cumulative winter CO 2 flux from agricultural land. We continuously observed CO 2 flux using automatically closing chambers at an untreated control plot and a plot with snow removal in northern Japan. The CO 2 in soil pores at 10-cm depth increased by 6.5ppmvday -1 as soil began to freeze, but it increased dramatically (to 49ppmvday -1) after snowmelt water infiltrated the soil and froze. The soil-frost layer constrained gas diffusion into the air, and the barrier strengthened as the frozen snowmelt water decreased the air volume in soil pores. Leached gas CO 2 from the freezing snowmelt water also increased gas CO 2 concentration in soil. As the soil thawed, the CO 2 concentration decreased drastically, at 790ppmvday -1. However, these changes had little effect on CO 2 flux. The soil CO 2 concentration remained stable after snow cover reached 30cm in the control plot. Low CO 2 flux in both plots occurred during the winter. No clear relation was found between CO 2 flux and snow depth or soil-frost depth because of the small CO 2 source at this site. We also considered how the presence of the chamber influenced soil temperatures and water contents. During the snow-free season, the chamber mitigated diurnal changes in soil temperature. The daily average soil temperature differed from that in the natural state by -1.7°C to 6.3°C. This fluctuation of temperature corresponded to the fluctuation of CO 2 flux, which ranged from 91% to 143% of the CO 2 flux in the natural state based on the temperature-response equations. The chamber had little influence on the soil temperature during the snow-cover period, and did not influence soil water content throughout the study period. Cumulative winter CO 2 emissions were 17.2gCm -2 (over 143 days) in the control plot and 13.4gCm -2 (over 151 days) in the treated plot (10.0 and 7.5% of annual accumulation, respectively).
UR - http://www.scopus.com/inward/record.url?scp=84864754422&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84864754422&partnerID=8YFLogxK
U2 - 10.1016/j.agrformet.2012.06.012
DO - 10.1016/j.agrformet.2012.06.012
M3 - Article
AN - SCOPUS:84864754422
VL - 165
SP - 25
EP - 34
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
SN - 0168-1923
ER -