Elucidation and Application of Ecosystem Recovery Mechanisms after Large-scale Fires
Toward the mitigation of global warming
In the Arctic region of North America, the scale of wildfires is increasing due to global warming. As a result, the way ecosystems recovery progresses after fires is changing, and it is urgent to elucidate the mechanism of ecosystem recovery from a new perspective. It is also necessary to develop various methods for ecosystem restoration after large-scale disturbance by applying the knowledge obtained in this study.
The landscape of a black spruce forest after a large fire in Alaska in 2004 (photo taken in 2005). With conventional fires, total destruction is rare, but with this fire, even the organic layer was burned away. As a result, the way how ecosystem recovery progresses has changed. It is necessary to elucidate the transition mechanism and develop conservation and restoration methods as soon as possible.
Changes in key ecosystem functions caused by wildfires. In the short term, CO2 is directly released during fires, and in the long term, CO2 absorption is reduced due to reduced photosynthesis and methane is released due to thawing of the permafrost. Thus, there are positive (exacerbating) feedback effects on global warming.
The belts of taiga and tundra in Alaska is a fire-prone area associated with lightning strikes, and ecosystem recovery has thus been acclimatized to fire. In the past, the fires were mostly canopy fires with low fire intensity that did not lead to the complete burning of organic layers including peat. In particular, black spruce was dominant on north-facing slopes, and fast forest regeneration was achieved immediately after canopy fires due to dispersion of black spruce seeds.
However, with the development of climate changes, wildfires are increasing in both intensity and frequency. During the 2004 Alaska wildfires, the total area burned exceeded that of Shikoku (Japanese fourth mainland), and the organic layer was also burned away. As a result, ecosystem recovery after large wildfires greatly differs from that after forest canopy fires. In particular, the existence of an organic layer is essential for seed germination and growth, and the development of methods to promote the establishment of Sphagnum moss as a base material is essential for organic matter accumulation. In addition, we studied the impact of wildfires on the ecosystems in the tundra zone.
Exploring Strategies for Coexistence between Indigenous Siberians and Wildlife
A practical study on an adaptive wildlife management system for utilization and protection of wild animals and birds
To reduce conflicts between local communities and wildlife (e.g., agricultural damage and invasive species problems), we plan and implement surveys and countermeasures with the participation and initiative of local residents, and provide bottom-up policy support. In recent years, we have also been involved in the establishment of wildlife sanctuaries to protect the livelihoods of indigenous people in Siberia.
◇ Survey of reindeer and other wild animals and establishment of protected areas
In the Arctic region of the Republic of Sakha in the Russian Federation, which is the closest Arctic area to Japan, we have attached satellite transmitters to wild animals (e.g., reindeer, musk ox, wolf) used by indigenous people to clarify the effects of global warming and seasonal migration. Based on this information, we are working with indigenous groups, local governments, hunting groups and other parties to establish and evaluate protected areas and hunting areas that contribute to traditional livelihoods.
◇ Survey of Migratory Birds in Japan and Evaluation of International Protected Areas
Siberia is an important breeding ground for migratory birds that use the arctic and other northern regions, including Japan, but their habitats are changing due to global warming. Therefore, we are conducting surveys, research, and practical applications to comprehensively evaluate the impact of global warming on habitat protection areas by creating a network of different surveys that have been conducted in individual countries.Shirow Tatsuzawa Assistant Professor
Glacier Ice Sheet-Ocean Interactions in Greenland
Warming Greenland's Coastal Environment
In Greenland, which is located in the Arctic region, the mass of the glacier ice sheet has been rapidly decreasing in recent years. We are conducting research using field surveys and satellite data, with the focus on the environmental changes along the coast of Greenland, where the glacier ice sheets meet the ocean.
Greenland is approximately six times the size of Japan, and 80% of its area is covered by glacial ice sheets. The ice in Greenland is rapidly diminishing due to the effects of global warming. In particular, glaciers flowing from the ice sheets into the ocean are undergoing remarkable changes, suggesting the influence of the warming ocean. In addition, the inflow of meltwater into the ocean is expected to raise sea levels and cause changes in ocean circulation and ecosystems, although the details are still unclear. Against this background, we are working to understand the interaction between glacier ice sheets and the ocean, and the resulting changes in the coastal environment of Greenland. We are conducting field observations and satellite data analysis with special focus on the Kanak region in the northwestern part of the country. Ultimately, we aim to clarify the impact of environmental changes on fisheries and traffic, and to provide feedback to local residents.
GFP and luciferase in copepods
Marine organisms include various bioluminescent creatures. We have identified a green fluorescent protein (GFP) and a secreted luciferase (luminescent enzyme) from copepods, the most dominant plankton species.
Zooplankton serves as energy transmitters in marine ecosystems, passing basic production to higher organisms. The dominant zooplankton species in the Arctic Ocean are copepods, most of which have a lifespan of one year or less, but their samples can be preserved semi-permanently with formalin fixation, making them an ideal taxonomic group for assessing the interannual variability in biological production in the region. Some species of copepods are also bioluminescent. It is thought that they emit light when they are about to be predated upon in dark waters, and use it to distract predators. We have identified a fluorescent protein (GFP) and a luciferase (luminescent enzyme) from copepods.
Remote Sensing of Ground Deformation in the Arctic
Detection of surface subsidence associated with permafrost thawing
Images of ground deformation can be detected from data obtained by the Synthetic Aperture Radar (SAR) onboard the Daichi satellite. Conventionally, the main target has been ground surface displacement caused by earthquakes and volcanic activity, but detection of local ground deformation that is not associated with earthquakes or volcanoes in the permafrost regions of the Arctic Circle has also started.
In the study of earthquakes and volcanic activity, the Earth's interior is sometimes estimated by capturing slight movement of the Earth's surface. This movement is called crustal movement, and efforts are still being made to improve the estimation accuracy and quality. Recently, interferometric SAR (SAR interferometry), which uses satellite SAR phase data, has made it possible to detect crustal movement in remote areas and overseas. In the Arctic, there is no so-called crustal movement, but as shown in the figure below, clear ground deformation has been detected in Western Siberia. This can be seen around so-called thermokarst terrain, which is often found in the Arctic, and is thought to represent subsidence of the ground surface due to the thawing of permafrost. Research on the formation process of thermokarst landforms, which has been largely untouched in the past, has just begun, and evaluation of the impact of global warming is an important issue for the future.
Resilience and Adaptive Capacity of Arctic Marine Systems under a Changing Climate
Overall understanding of marine ecosystems throughout the Arctic Rim
International workshops have been held to present individual research results of existing research projects in the pan Arctic seas (i.e., the Arctic Ocean and adjacent subarctic seas), which have been underway in Japan, the U.S., and Norway, with the aim of achieving an overall understanding of the results in each area by identifying similarities and differences.
The objective of this study is to provide an overall understanding of the response of marine ecosystems to environmental change in the Pacific-Arctic-Atlantic region by identifying similarities and differences in the circumpolar pan Arctic seas (i.e., the Arctic Ocean and adjacent subarctic seas). The Ecosystem Studies of Sub-Arctic and Arctic Seas (ESSAS), a regional research program of the Integrated Marine Biosphere Research (IMBeR), is the parent organization of this project. The research is promoted mainly by the scientific steering committee members from Japan, the United States, and Norway. Between 2015 and 2018, in particular, three international workshops were held to present the results of existing research in each country and to promote an integrated understanding of marine ecosystems throughout the pan Arctic seas.Sei-Ichi Saitoh