Dr. Ito of the Ecosystem Change Research Program, Frontier Research Center for Global Change, received the Outstanding Paper Award from the Society of Agricultural Meteorology of Japan. This is awarded annually to a few authors who have recent publication from Journal of Agricultural Meteorology. The winning paper was titled "High-Resolution Mapping of the Net Primary Productivity of Terrestrial Ecosystems in East Asia Using a Process-based Model" (Journal of Agricultural Meteorology, 59:23-34, in Japanese with English summary).
In this paper, to perform high-resolution mapping of terrestrial vegetation processes, Dr. Ito applied a terrestrial carbon cycle model (Sim-CYCLE: Simulation model of Carbon cYCle in Land Ecosystems) developed in the Ecosystem Change Research Program, in conjunction with a satellite-based land cover map and high-performance computer. The spatial resolution is as high as 5 minutes in longitude and latitude. In recent years, it has been recognized that spatial heterogeneity is critically important in evaluating the atmosphere-ecosystem carbon dioxide exchange with high accuracy, and then should be included by high-resolution model simulations. In general, spatial heterogeneity of land surface is induced by various factors such as topography, micrometeorology, and land-use change. Although such spatial heterogeneity was expected to affect ecosystem carbon budget, most terrestrial ecosystem models, which had coarse spatial resolutions (e.g. 50 km), could not appropriately take it into account. However, a model with an unprecedentedly high spatial resolution was developed, by using recent data of topography, soil, and land cover and high-performance computers. The paper presented the first result and analyses of net primary production, an index of vegetation function, in East Asia, estimated by the high-resolution model. By comparing with empirical models and observational data, the simulation result was adequately validated. Another unique point of the research is that a process-based model was used to perform simulation, in which physiological properties and environmental regulations of plant photosynthesis and respiration are explicitly included. Such process-based models have relatively complicated structure and demand high computational cost, but enable us to analyze ecological processes in detail and to make predictions. In his forthcoming studies, Dr. Ito will develop higher resolution models using updated satellite data and validate models with additional observations such as flux measurement data.
The model study is apparently beneficial for evaluating the direct effects of climate change on terrestrial ecosystems, indirect effects on human society, and feedback processes from ecosystem to climate system. For example, the high-resolution model may be useful in the greenhouse gas budgeting in the framework of the Kyoto Protocol, which requires us to quantify the net budget of greenhouse gases in forest ecosystems with high accuracy.