In the early 1980s there were several published reports of recent, unexplained increases in mortality of red spruce in the Adirondack Mountains and the northern Appalachian Mountains of the eastern United States. These reports coincided with documentation of reductions in radial growth of several species of pine in the southeastern United States, and with the severe, rapid, and widespread decline of Norway spruce, silver fir, and some hardwoods in central Europe. In all of these instances, atmospheric deposition was hypothesized as the cause of the decline. (Throughout this volume, we use the term "decline" to refer to a loosely synchronized regional-scale deterioration of tree health which is brought about by a combination of stress factors. These may be biotic or abiotic in nature, and the combinations may differ from site to site. ) Heated public debate about the causes and possible cures for these forest declines ensued. Through the course of this debate, it became clear that information about forest health and air pollution effects on forests was inadequate to meet policymakers' needs. Ecology and Decline of Red Spruce in the Eastern United States addresses that gap for eastern spruce fir forests and represents the culmination of a great deal of research conducted in recent years. The focus is on red spruce because the decline of red spruce was both dramatic and inexplicable and because of the great amount of information gathered on red spruce.

Over the past decade there has been considerable interest in the effects of atmospheric deposition on forest ecosystems. This volume summarizes the results of the Integrated Forest Study (IFS), one of the most comprehensive research programs conducted. It involved intensive measurements of deposition and nutrient cycling at seventeen diverse forested sites in the United States, Canada, and Norway. The IFS is unique as an applied research project in its complete, ecosystem-level evaluation of nutrient budgets, including significant inputs, outputs, and internal fluxes. It is also noteworthy as a more basic investigation of ecosystem nutrient cycling because of its incorporation of state-of-the-art methods, such as quantifying dry and cloud water deposition. Most significantly, the IFS data was used to test several general hypotheses regarding atmospheric deposition and its effects. The data sets also allow for far-reaching conclusions because all sites were monitored over the same period using comparable instruments and standardized protocols.

Despite effective global-scale legislation to restrict the emissions of nitrogen (N) into the atmosphere, atmospheric deposition of N remains high in many forested regions. In addition, many N-impacted forests still retain the imprint of N saturation, such as altered species composition and leaching of essential base cations. Accordingly, we need a further understanding of the complexities of N cycling in forest ecosystems and the effects of excess N on forest biodiversity and biogeochemical cycling. This volume explores these complexities, including effects on plants, plant assemblages, and forest biogeochemistry, by synthesizing research from Asia, Europe, and North America. Because of the widespread nature of current declines in N deposition, this book ends with a look to the future as N-impacted forests experience a return to lower levels of atmospheric deposition of N.

The Fernow Watershed Acidification Study is a long-term, paired watershed acidification study. This book describes the responses to chronic N and S amendments by deciduous hardwood forests, one of the few studies to focus on hardwood forest ecosystems. Intensive monitoring of soil solution and stream chemistry, along with measurements of soil chemistry, and vegetation growth and chemistry, provide insights into the acidification process in forested watersheds.

The most comprehensive existing volume of multidisciplinary research by top ecologists on the herbaceous layer of forests.