Date: November 29-30, 1999
Place: Nagoya
University, Nagoya, Japan
Chief Organizers:
Hajime Akimoto (Tokyo
University)
Hiroshi
Sakugawa (Hiroshima
University)
Invited speakers:
About 20 scientists from Japan
About 10 scientists from North America, Europe and Asia
Poster presentations: about 50
Expected attendants: 150-200
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Background: Visible injury, lack of vitality and decline of forests has been attributed to the widespread effects of air pollution for over 20 years. Acute damage to trees and other vegetation was well known from much earlier, close to specific sources of air pollution. The widespread nature of the problem was initially highlighted by observations in the 1970s of needle injury and growth reduction of Ponderosa pine forests in southern California. In this case, the damaging agents were identified as ozone and other photochemical oxidants formed from the action of sunlight on mixtures of unburned hydrocarbons and nitrogen oxides. In the 1980s the focus moved east, to the Appalachian Mountains, and to Europe, where symptoms of a 'new type' of forest decline were appearing. A large number of hypotheses were proposed to explain the observations, including both natural and man-made stresses. Major research programs were established to elucidate the mechanisms of 'damage', and to evaluate the role of pollutants, either as direct agents, or acting indirectly through modifying soils or plant responses to other stress factors. The most likely damaging pollutants, shown to produce measurable effects in controlled experiments with seedlings and young trees, are acidic mist and ozone, although effects of other pollutant gases close to sources are also possible. In the field, experiments have shown the effects of acid deposition (wet and dry) on soil acidity, leading to enhanced leaching of base cations in soil, and sometimes producing nutrient deficiencies. In Europe, however, acid deposition has occurred simultaneously with deposition of large amounts of 'pollutant' nitrogen, which has been shown to cause large-scale effects on forests, including increased growth. Separating the different effects of acidity, sulfate and nitrogen-containing ions has proved difficult in the field. It has also become clear that natural stresses, either climatic or by pathogens, play an important role in the vitality of forests, and the way in which they respond to air pollution. In Japan, it has been found
that the significant decline of forests, dominated by pine, fir, cedar,
beech etc., largely occurred during the last half century. The interactive
effects of attack by insects or diseases, changes in successional status
and air pollution /acid rain were suggested as the causes of decline. Especially
for the pine forests, most of researches focused on the infection of a
parasite, pinewood nematode, and therefore the demarches for pine decline
mainly depended on the extermination of nematodes. Now, several investigators
survey not only the effects of parasite but also pollutants on pine-tree
vigor and then try to integrate the informations about the factors of forest
decline.
Purpose: Although much work on air pollutant effects on plants has been done in Japan, the rapid growth of industrialization in East Asia, and recent increases in forest health problems in this region have encouraged new research. There is a need to improve our knowledge and understanding of the problem. In particular, demonstrable cause-effect relationships for forest trees and quantitative dose-response functions for individual pollutants are still lacking. The objectives of the symposium are, 1) to review the experiences from forest decline studies across the world, especially in relation to cause and effect, 2) to formulate strategies for studying forest decline in the East Asia, 3) to develop methods for establishing quantitative dose-response relationships, 4) and to organize a world-wide network for researchers on air pollution and forest decline. This symposium is organized
by the Core Research for Evolutional Science & Technology (CREST) Program
of Science and Technology Corporation. The CREST Program, which started
in 1996 and will end in 2001, studies on forest decline caused by air pollution/acid
deposition in Japan. Twenty to thirty scientists from a number of universities
and institutes in Japan make a team to study forest decline in Japan. In
this symposium, the activities of the research project will be introduced,
and the investigators who are involved in the project will present recent
field and simulation results concerning forest decline.
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