16:00 〜 16:15
[ACG37-09] 大規模風倒被害後の植生遷移にともなうCO2収支の変化
キーワード：撹乱、二次遷移、CO2収支、森林生態系
Forest ecosystems are expected to be a major sink of atmospheric carbon dioxide (CO2), whereas their ability to absorb CO2 is severely perturbed by artificial and natural disturbances, such as deforestation, fires, and windthrow. Many studies which adopted the chrono-sequence approach reported that such severe disturbances often changed forest to a large CO2 source. However, there are few studies that directly measure CO2 flux for a long term (more than a decade) above a disturbed forest site during secondary succession after severe disturbance.
A flux site of a larch plantation in Hokkaido, Japan was struck by a typhoon in September 2004. Because of wind storm, about 90% of trees fell down. The fallen trees were removed by heavy machinery from the site, through which the soil surface and understory species were also disturbed. After the operations of timber transport, secondary succession progressed naturally in the ex-forest site. We recommenced flux measurement in August 2005. CO2 flux has been measured by the eddy covariance technique with an open-path CO2 / H2O analyzer (LI7500, Licor) during a snow-free period from mid-April to mid-November. Cumulative net ecosystem CO2 exchange (NEE) during the growing season from May through October significantly decreased with time between 2006 and 2023. This decreasing trend was caused by the increase of gross primary production (GPP) or ecosystem photosynthesis, which corresponded to vegetation recovery through secondary succession; dominant plant species changed from small shrubs to deciduous trees.
A flux site of a larch plantation in Hokkaido, Japan was struck by a typhoon in September 2004. Because of wind storm, about 90% of trees fell down. The fallen trees were removed by heavy machinery from the site, through which the soil surface and understory species were also disturbed. After the operations of timber transport, secondary succession progressed naturally in the ex-forest site. We recommenced flux measurement in August 2005. CO2 flux has been measured by the eddy covariance technique with an open-path CO2 / H2O analyzer (LI7500, Licor) during a snow-free period from mid-April to mid-November. Cumulative net ecosystem CO2 exchange (NEE) during the growing season from May through October significantly decreased with time between 2006 and 2023. This decreasing trend was caused by the increase of gross primary production (GPP) or ecosystem photosynthesis, which corresponded to vegetation recovery through secondary succession; dominant plant species changed from small shrubs to deciduous trees.