MAPPING OF ATMOSPHERIC POLLUTION IN TOKYO BASED UPON EPIPHYTIC BRYOPHYTES

抄録

Epiphytic bryophytes on broad-leaved trees in Tokyo Metropolis was investigated to estimate the extent of atmospheric pollution. The investigation shows a geographical decline of epiphytic bryophytes both in luxuriance and in the number of species. The metropolitan area was divided into five zones according to the vegetation of the epiphytic bryophytes. The zones evidently show the extent of phytotoxic pollutants in the atmosphere. Sulfur dioxide is more toxic to bryophytes than any other pollutants which are monitored in the area investigated. The average concentration of sulfur dioxide corresponding to the decline of epiphytic bryophytes was estimated in each zone. It is over 0.05 ppm in zone I, 0.04-0.05 ppm in zone II, 0.02-0.04 ppm in zone III, 0.01-0.02 ppm in zone IV, and below 0.01 ppm in zone V. Epiphytic bryophytes are used practically as an indicator of atmospheric pollution, because they are very sensitive to it, frequently appear on trees in the urban area and are easy to identify in the field. It is certain that the investigation of epiphytic bryophytes provides us with very useful information about the atmospheric pollution, even if it is too slight for chemical methods.