The idea for this book arose in 1993, after the Free State of Bavaria through its Bayrisches Staatsministerium rur Landesentwicklung und Umweltfragen (Bavarian Ministry of Regional Development and the Environment) decided to discontinue both the Bavarian project management (PBWU) for forest decline research and the multidisciplinary field research on the Wank Mountain in the Alps near Garmisch. Forest decline through the action of ozone and other photooxidants was a main topic of the supported re­ search in the Alps and will be a topic of new investigations in the Bavarian Forest. Many interesting results were obtained, but the researchers involved have not had sufficient time to allow reliable conclusions to be drawn. It was therefore decided to ask inter­ national experts for contributions in order to summarize the best available evidence of a possible link between ozone and forest decline - a topic which has been studied in the USA since the late 1950s and in Europe since the early 1980s. The original idea of Waldsterben as an irreversible large-scale dieback of forests in Germany was soon recognized to be wrong (Forschungsbeirat 1989). However, the new criteria used for the official German and European damage inventories (loss or yel­ lowing of needles or leaves, tree morphology) indicate that per­ sistently high percentages of damaged spruce and pine remain, and there is an increasing percentage of damaged beech and oak, with a high proportion of biotic disease (Forschungsbeirat 1989; UN-ECE 1995).

Inhalt

1 Ozone Formation, Destruction and Exposure in Europe and the United States.- 1.1 Introduction.- 1.2 The Chemistry of Tropospheric Ozone Formation.- 1.3 Urban Ozone Formation and Transport to Mountain Sites.- 1.4 Meteorological Effects on Tropospheric Ozone Concentrations.- 1.5 Ozone Networks and the Analysis of Measurements.- 1.6 The Global Distribution of Ozone Concentrations and the Seasonal Cycle.- 1.7 Long-Term Trends in Tropospheric Ozone Concentrations.- 1.8 Present Ozone Concentrations and Ozone Exposure over Europe and North America.- 1.9 Dry Deposition of Ozone.- 1.10 Conclusions.- References.- 2 Ozone and Its Known and Potential Effects on Forests in Western United States.- 2.1 Introduction.- 2.2 Spatial Distribution and Temporal Trends of Ozone in Relation to Geographic Setting and Summer Climate.- 2.2.1 Daily Patterns of Ozone Concentrations in Rural Mountain Locations.- 2.2.2 Spatial Variation of Ozone in the Sierra Nevada and San Bernardino Mountains.- 2.2.3 Temporal Trends of Ozone and the Outlook for the Future.- 2.3 History of Ozone Damage to Californian Forests.- 2.3.1 Field Identification of Ozone Injury.- 2.3.2 Role of Other Biotic and Abiotic Stresses.- 2.3.3 Crown Changes Associated with Chronic Ozone Injury.- 2.3.4 Spatial Distribution and Temporal Changes of Ozone Damage.- 2.3.4.1 Southern California.- 2.3.4.2 Sierra Nevada.- 2.4 Experimental Exposures of Western Conifers to Ozone.- 2.4.1 Foliar Injury Symptomatology.- 2.4.2 Physiological Responses: Gas Exchange and Photosynthesis.- 2.4.3 Growth Responses of Seedlings and Saplings.- 2.5 Effects of Chronic Ozone Exposure on Radial Growth in the Sierra Nevada and San Bernardino Mountains.- 2.5.1 Seasonal Radial Growth Responses.- 2.5.2 Long-Term Radial Growth Responses.- 2.5.2.1 Direct Effects of Ozone on Radial Growth.- 2.5.2.2 Effects of Ozone Together with Climate on Tree Growth.- 2.5.3 Relationship Between Needle Retention and Radial Growth Reductions.- 2.5.4 Development and Composition of Ozone-Exposed Forests Under Euro-American Settlement Influences.- 2.5.4.1 Chronic Ozone Injury and Mortality of Pines Due to Bark Beetle.- 2.5.4.2 Ozone Influences on Recruitment and Mortality of Ponderosa Pine Seedlings.- 2.5.5 Status of Models for Simulating Ozone Effects on Tree Growth and Stand Development.- 2.6 Summary.- References.- 3 Ozone and Its Known and Potential Effects on Forests in Eastern United States.- 3.1 Introduction.- 3.2 Recent Findings from Northeastern Forests.- 3.3 Recent Findings from Northcentral Pennsylvania..- 3.4 Recent Findings from the Shenandoah National Park, Virginia.- 3.5 Recent Findings from Southern United States..- 3.6 Recent Findings from Great Smoky Mountains National Park.- 3.7 General Conclusions.- References.- 4 Ozone and the Forests in Austria and Switzerland.- 4.1 Introduction.- 4.2 O3 Levels and Areas at Risk in the Alps of Central Europe.- 4.3 Tree Responses to O3 Levels at Forest Sites.- 4.3.1 Experimental O3 Exposure of Twigs of Mature Norway Spruce and European Larch Trees in Austrian Forests.- 4.3.1.1 Study Sites, Pollution Load, and Experimental Design.- 4.3.1.2 The Effects of the Various O3 Exposure Regimes.- 4.3.1.3 Stomatal Control of Ozone Uptake.- 4.3.1.4 Detoxification Capacity.- 4.3.2 The Swiss Research Program "Air Pollution and Forest Decline".- 4.3.2.1 Effects of Air Pollutants on the Gas Exchange of Spruce.- 4.3.2.2 Analysis of the Needle Wax Layer, Stem Production, and Fungal Impact.- 4.3.2.3 Experiments on the O3 Sensitivity of Forest Trees.- 4.3.3 Other Field Research on Trees in Switzerland.- 4.4 Mechanisms of O3 Impact on Trees Under Controlled Exposure Conditions.- 4.5 Evidence of O3 Injury on a Regional Scale?.- 4.5.1 Methods of Estimating Forest Condition.- 4.5.2 Spatial Associations Between the Occurrence of Ozone and Crown Conditions.- 4.5.3 Associations of Temporal Trends in O3 Concentration and Crown Condition.- 4.5.4 Is there any Unambiguous Evidence of O3 Injury to Trees in Switzerland and Austria?.- 4.6 Conclusions.- References.- 5 Role of Ozone in Forest Decline on Wank Mountain (Alps).- 5.1 Introduction.- 5.2 Site Characteristics.- 5.2.1 The Bavarian Alps.- 5.2.2 The Wank Mountain Research Site.- 5.2.3 Tree Vitality at the Research Site.- 5.3 Atmospheric Exposure.- 5.4 Soil Characteristics and Tree Nutrition.- 5.5 Physiological Observations.- 5.5.1 Ozone.- 5.5.2 Other Photo-oxidants.- 5.6 Conclusions.- References.- 6 Ozone Responses of Trees: Results from Controlled Chamber Exposures at the GSF Phytotron.- 6.1 Introduction.- 6.2 Chamber Design and Performance.- 6.3 Selected Exposure Experiments.- 6.3.1 Interactions Between Ozone and Acidic Mist.- 6.3.2 Interactions Between Ozone and Carbon Dioxide..- 6.3.3 Effects of Mixtures of Air Pollutants.- 6.4 Biochemical Responses to Ozone.- 6.4.1 Response Levels.- 6.4.2 Photosynthetic Pigments.- 6.4.3 Polyphenolic Metabolites.- 6.4.4 Polyamines and Ethylene.- 6.4.5 Ozone-Related Proteins.- 6.4.6 Lignins.- 6.5 Premature Senescence in Beech.- 6.6 "Memory" Effects for Ozone in Conifers.- 6.7 Conclusions.- References.- 7 Controlled O3 Exposures and Field Observations of 03 Effects in the UK.- 7.1 Introduction.- 7.2 The 03 Climate of the UK.- 7.3 Surveys of Tree Health.- 7.3.1 Sitka Spruce.- 7.3.2 Norway Spruce.- 7.3.3 Scots Pine.- 7.3.4 Oak.- 7.3.5 Beech.- 7.3.6 Ash.- 7.3.7 Yew.- 7.3.8 UN-ECE Surveys.- 7.3.9 The Early Diagnosis Survey.- 7.4 Long-Term Ozone Exposures.- 7.4.1 Filtration Experiments.- 7.4.2 Fumigation Experiments.- 7.4.3 The Liphook Field Exposure Experiment.- 7.5 Ozone-Induced Changes in Epicuticular Waxes.- 7.6 Effects of O3 on Winter Hardiness and Frost Injury.- 7.7 Effects of Ozone on Nutrient Leaching.- 7.8 Effects of Ozone on Photosynthesis and Carbon Allocation.- 7.8.1 Photosynthetic Capacity.- 7.8.2 Carbon Allocation and Utilization.- 7.9 Interactive Effects of Ozone.- 7.9.1 Biotic Factors.- 7.9.2 Water Relations of Deciduous Trees.- 7.10 Conclusions.- References.- 8 Controlled Ozone Exposures and Field Observations in Fennoscandia.- 8.1 Land Use in Fennoscandia.- 8.2 Ozone Concentrations in Fennoscandia.- 8.3 Forest Health.- 8.3.1 Finland.- 8.3.2 Norway.- 8.3.3 Sweden.- 8.3.4 Denmark.- 8.3.5 Resin-Flow Disease in Norway Spruce.- 8.4 Exposure Facilities - Open-Top Chambers and Open-Release Systems.- 8.5 Ozone-Induced Changes in Structure.- 8.5.1 Controlled Exposure Experiments - Conifers.- 8.5.2 Controlled Exposure Experiments …