The negative impacts of environmental change, including global warming, on terrestrial ecosystems is of deep concern. It has been well pointed out that ecosystems in mountain areas are particularly fragile and sensitive to such environmental changes. Carbon is the most important element in material cycles but it is also a source of CO2, the primary gas responsible for the greenhouse effect. Vegetation reduces excess carbon via photosynthesis, but it releases carbon via respiration. By monitoring the behavior of the carbon cycle associated with vegetation, we should be able to elucidate the effects of global warming on the carbon cycle.
The objective of our group is to elucidate the carbon cycle of terrestrial ecosystems. To complete this objective, we carry out field observations and develop a way to parameterize the carbon cycle and to expand the observation results from a specific site to a larger scale. Also, we focus on the temperature dependence of soil respiration to assess the effects of global warming on ecosystems. The carbon cycle associated with human activity should be evaluated, as well as the carbon cycle in the ecosystems, for appropriate assessments. So we endeavor to investigate the carbon cycle associated with forestry (Fig. 1). The above recognitions eventually led us to set the following specific research issues:
1) To establish a means of assessment of the carbon balance on a large spatial scale.
2) To reveal the relationship between soil respiration and environmental factors.
3) To quantify the carbon budget in wood distribution systems.
Furthermore, we encourage the participation of students to advance the cultivation of human resources that will contribute to sustainable developments in the world. Also, we promote public relations to present our findings for students and residents through workshops or academic meetings.
3. Research issues
To achieve the above goals, we conduct the following researches.
1) Quantifying carbon balance by continuous monitoring.
Biomass, Net primary production, Leaf Area Index, Photosynthesis, Soil carbon, Soil respiration, Carbon fixation.
2) Elucidating and parameterizing soil carbon dynamics.
Reveal soil respiration processes (e.g., relation to vegetation type, altitude, temperature dependence).
Reveal the relationship between soil respiration and the balances of phosphorus and nitrogen.
3) Estimating and spatial variations in the Leaf Area Index (LAI) and its expansion.
4) Life cycle assessment of wood production; carbon budget associated with wood utilization.
4. Cooperation within and without the group
The first step within the group is to improve on a common means of assessment. We endeavor to establish a protocol for assessing the carbon cycle through our observations in eight field sites for the construction of an integrated observation system in sensitive mountain ecosystems.
This cooperation will contribute to the following:
1) Communization of a basic technique of assessment, which can homogenize data quality and facilitate the comparison of observation results in the eight sites.
2) Elucidation of the relationship between soil respiration and environmental factors.
3) Expanding the technique of carbon budget assessment by parameterizing the input data of the model simulation.
Furthermore, the observation data provided by other groups will improve our research. For example, mapping a carbon budget requires meteorological observation data. In particular, climate change scenarios and ecosystem changes increase our understanding of the change of spatiotemporal distribution in carbon.
5. Future works
The research plans for the next year are as follows:
1) Continuous observation.
2) Demonstration of soil respiration measurements for sharing findings and techniques.
3) Isolation of root respiration and other heterotroph respiration.
4) Quantification of dead woods, slashes, and CO2 release associated with the decomposition of woods.
5) Revealing the effects of microbial activities on phosphorus and nitrogen cycles.
6) Quantification of the output of DOC from forested catchments, focusing on the difference between a deciduous broad-leaved forest and an evergreen coniferous forest.
1) A trial map based on Landsat/TM data will be formulated using data obtained in June 2000
Life cycle assessment
1) Investigation of life cycle assessment for a Hinoki (Japanese cypress) forest in the southern part of Nagano Prefecture.
Furthermore, several experiments will be required to elucidate the responsive property of the carbon cycle to the environmental change. Toward that end, incubation in experimental facilities is one of the possibilities.