In recent years, photochemical oxidant concentration has increased continually in Japan. The current ozone level has a potentially adverse effect on plants. Forest health monitoring surveys have been carried out, but effects of air pollutants on plants have not been clarified. In this study, we analyzed observation data using a geographic information system (GIS) to evaluate, both regionally and visually, the relationship between air pollutants and plant decline, as represented by data of Japanese cedars (Cryptomeria japonica D. Don). Japanese cedar forests in the Kanto plains of central Japan were studied. Cumulative exposure over a threshold of 40 ppb (AOT40) based on photochemical oxidant concentrations at all air pollutant monitoring stations showed a gradual upward trend from 1982 after a rapid decrease from 1975. The AOT40 values vary annually to a great degree: high AOT40 values were observed in hot summer years. Distributions of AOT40 values were compared to plant decline information from Nashimoto (1990) and Matsumoto et al. (2002). Severely damaged Japanese cedars were distributed in regions of less than 100 m altitude, less than 1000 mm precipitation during April-September, less than 20% forest coverage, and a leaf area index (LAI) of less than 1.5. The distribution of severely damaged stands coincided approximately with the regions of average AOT40 equal to 10 000 ppb-hr.
|ジャーナル||Journal of Global Environment Engineering|
|出版ステータス||Published - 2007 3|
ASJC Scopus subject areas
- Global and Planetary Change
- Geography, Planning and Development
- Management, Monitoring, Policy and Law