Biography & Abstract



Prof. Hideaki Shibata

Hokkaido University



Hideaki Shibata received PhD in 1996 from Hokkaido University, worked as assistant professor (1996-2001), associate professor (2001-2010), and professor (2011-current) of Hokkaido University. Hideaki Shibata is currently serving the co-chair of the International Long-Term Ecological Research Network (ILTER) since October 2016.His research interest involves biogeochemistry, soil and water quality in forest ecosystem.  He is recently working on ecosystem functions and services in forest under changing environments, and on nitrogen footprint assessment as environment indicators of human activities.  He is also in charge of Graduate School of Environmental Science (Course of Forest Conservation) for education of graduate students.


Title: Changing winter climate alter nitrogen biogeochemistry in northern forest ecosystems

Abstract:  Nitrogen cycle is key process to support ecosystem productivity and functioning, affected by various natural and anthropogenic disturbances. Climate changes are one of the strong drivers to alter the cycle of nitrogen through various pathways. Changes in temperature and precipitation directly affect soil microbial vitality that contribute to nitrogen mineralization, immobilization, nitrification, denitrification, and leaching in the soil system. Winter climate (i.e., decrease of snowfall, increase of soil freezing-thawing events and/or increase of winter rainfall) has been recognized to influence the microbial nitrogen transformation even beneath the snowpack during the mid-winter. Those perturbations of nitrogen cycle in winter by climate change might cause significant impact for the ecosystem processes during the following growing season. I present the recent research findings on the effect of snowpack decrease and increase of soil freeze-thaw cycle on nitrogen cycles in northern forest ecosystems using in-situ experimental manipulation of snowpack in Hokkaido, northern Japan.  The increase in soil freezing-thawing cycles significantly altered soil nitrogen processes especially for net ammonium production as a source of microbial nitrification, plant nutrient uptake and nitrogen leaching from soil system during the following growing seasons. Those impacts would be important to predict future changes of forest structure and functions under various environmental changes not only for climate changes but also change in atmospheric nitrogen deposition. Further knowledge gaps and future research needs will be also addressed.