Biogeochemical Cycling in the Arctic Terrestrial Ecosystem, Permafrost and Periglacial Regions
Background and Objectives
Tundra and forest ecosystems in the circumpolar region are expected to be affected by permafrost degradation and glacier retreat associated with Arctic warming. However, there are insufficient observational data to support ecosystem responses to permafrost degradation and glacier retreat, and the overall picture of the terrestrial interaction system that is necessary for future projections is not yet clear. In recent years, the Arctic Council (AC) member states have been strengthening their observations of the Arctic. Japan, as an observer country, is expected to provide scientific knowledge that can be returned to governments of AC member states, working groups, and local residents, while utilizing the observation sites that are being developed within AC member states.
Research Program on Land aimed to elucidate the actual state of biogeochemical cycles, mainly greenhouse gases, focusing on tundra and forest ecosystem changes, permafrost degradation, and mountain glacier retreat. In particular, the actual conditions of biodiversity and carbon fixation functions, interactions between soil microbiota and vegetation in permafrost, and biogeochemical cycle processes associated with melting excess ice and glaciers are not well understood due to insufficient understanding of the actual situation. This Research Program contributes to a better understanding of the effects of global warming on the biogeochemical cycle, especially carbon cycle, and the results are used to improve ecosystem models and Earth system models. Three Sub Programs (Tundra Ecosystem, Boreal Forest Ecosystem, Permafrost and Arctic Mountain Glacier Landforms) were set up and studied to report the consequences of the Arctic warming on ecosystems, permafrost, and glaciers to international communities.
Sub Program 1
In Sub Program 1, we used observations in high-latitude tundra and integrated analysis of existing observational data and databases to understand the response of biodiversity to warming and to identify biodiversity-driven ecosystem functions, particularly carbon sequestration capacity, including the effects of tundra vegetation and soil interactions and glacier landforms (glacier melt), and the analysis of latitudinal gradient of environment.
Sub Program 2
In Sub Program 2, research was conducted to elucidate changes in the boreal forest ecosystem and greenhouse gas dynamics through long-term observations of the boreal forest ecosystem, based on the strong possibility that the biogeochemical cycle processes in the boreal forest ecosystem are affected by changes in temperature and rainfall patterns due to global warming and the thawing of permafrost.
Sub Program 3
Sub Program 3 focused on permafrost areas and mountain glacier terminuses, which are undergoing accelerated changes due to rapid temperature rise, and investigated the dynamics of greenhouse gases in mountain glacier basins, particularly methane gas, mercury concentrations in permafrost, and its discharge process from rivers to the Arctic Ocean by analyzing permafrost samples and seafloor sediments offshore Alaska obtained by the Research Vessel Mirai Arctic cruise.
Summary
In this Research Program, biodiversity studies, observational studies of greenhouse gas dynamics, and model analyses progressed in parallel. Observational research in the Arctic was restricted due to the COVID-19 pandemic and the subsequent international situation, and in the first half of the project period, the project participants were unable to complete the research as originally planned. However, strengthened relationships with local collaborators enabled deeper support for field observations and the sharing of existing data, which, while not perfect, enabled the substitution of field research and led to successful results.
Continuous observation data acquisition in Russia has been interrupted since 2022, when the Russia-Ukraine war began. Excluding observations in Russia may cause a significant bias in the assessment of terrestrial ecosystems. In order to understand more accurately environmental changes in the Arctic as a whole, research to understand the actual conditions on the Eurasian continent remains an important theme, and it is essential to urgently consider alternative research methods for field surveys, taking into account the international situation.
