[ACG54-P10] つくばアカマツ林における土壌炭素フラックスに対する長期的な温暖化の影響
キーワード：土壌呼吸、メタン、チャンバー、地球温暖化
Globally, soil contains about 3000 Gt of organic carbon. Annually, about 98 GtC is released to the atmosphere from soil as CO2 (soil respiration, Rs). Rs consists of root respiration and heterotrophic respiration (Rh), and Rh contributes to more than the half of soil respiration. On the other hand, upland soil uptakes CH4. Therefore, soil (especially forest soil) is a large source for CO2 and sink for CH4. Long-term response of those soil carbon fluxes to warmer environment is a key for mitigation and adaptation for future climate change. However, long-term continuous monitoring data for those soil carbon fluxes are totally limited.
To examine the long-term response of Rh to global warming in Asian monsoon forests, we set multi-channel automated chamber measurement system in a red pine forest in Tsukuba in February 2006. We prepared 12 trenched chambers (90 cm × 90 cm × 50 cm) to continuously measure Rh. Half of those trenched chambers were artificially warmed by infrared heaters 1.6 m above the soil surface (+2.5°C), and influence of soil warming on Rh was examined by comparing control plots and warming plots. In July 2009, we added 8 chambers to measure Rs. Further, we started continuous measurement of soil CH4 flux in June 2019 using the same chamber measurement system by connecting control unit with CH4 analyzer (915-0011, Los Gatos Research, Inc., USA).
Remarkable exponential relationships between soil temperature and soil CO2 effluxes (Rs and Rh) were confirmed every year. In addition, soil CO2 effluxes were observed to be related with soil moisture especially in summer period from July to September. On the other hand, we found that soil CH4 was negatively related with soil moisture. Those observations suggest that soil temperature is the primary factor controlling soil CO2 effluxes, whereas soil moisture is the main factor controlling soil CH4 uptake in our study site.
To examine the long-term response of Rh to global warming in Asian monsoon forests, we set multi-channel automated chamber measurement system in a red pine forest in Tsukuba in February 2006. We prepared 12 trenched chambers (90 cm × 90 cm × 50 cm) to continuously measure Rh. Half of those trenched chambers were artificially warmed by infrared heaters 1.6 m above the soil surface (+2.5°C), and influence of soil warming on Rh was examined by comparing control plots and warming plots. In July 2009, we added 8 chambers to measure Rs. Further, we started continuous measurement of soil CH4 flux in June 2019 using the same chamber measurement system by connecting control unit with CH4 analyzer (915-0011, Los Gatos Research, Inc., USA).
Remarkable exponential relationships between soil temperature and soil CO2 effluxes (Rs and Rh) were confirmed every year. In addition, soil CO2 effluxes were observed to be related with soil moisture especially in summer period from July to September. On the other hand, we found that soil CH4 was negatively related with soil moisture. Those observations suggest that soil temperature is the primary factor controlling soil CO2 effluxes, whereas soil moisture is the main factor controlling soil CH4 uptake in our study site.