In the past century, anthropogenic activities have increased N input drastically to terrestrial ecosystems and influenced the global N cycle. Especially temperate forest ecosystems are affected in their productivity, species composition, soil chemistry and water quality. N input to forest ecosystems is retained in trees and soil. Excessive N is leached out or released as gases. The retention of N input in soils is mainly influenced by the stability of soil organic matter (SOM). Many forests in central Europe and North America have been subjected to N saturation, i.e. excessive N appeared as nitrate in the leachate below the rooting zone. Reduction of atmospheric N emission and consequent atmospheric N deposition is proposed to be the only practical long-term solution to improve N-saturated forest ecosystems. However, responses of N-saturated forest ecosystems to reduced atmospheric N deposition have been seldom investigated. In the present study, atmospheric deposition was manipulated through roof constructions below the canopy of a mature Norway spruce forest on the Solling plateau in central Germany. A £^(5)N tracer field and a density fractionation laboratory experiment were conducted in the present study to investigate the influence of long-term reduced atmospheric N deposition on the partitioning of atmospheric N in different forest ecosystem compartments as well as on the partitioning of atmospheric N retained in the soil in different SOM pools.

Presenting the first continental-scale assessment of reactive nitrogen in the environment, this book sets the related environmental problems in context by providing a multidisciplinary introduction to the nitrogen cycle processes. Issues of upscaling from farm plot and city to national and continental scales are addressed in detail with emphasis on opportunities for better management at local to global levels. The five key societal threats posed by reactive nitrogen are assessed, providing a framework for joined-up management of the nitrogen cycle in Europe, including the first cost-benefit analysis for different reactive nitrogen forms and future scenarios. Incorporating comprehensive maps, a handy technical synopsis and a summary for policy makers, this landmark volume is an essential reference for academic researchers across a wide range of disciplines, as well as stakeholders and policy makers. It is also a valuable tool in communicating the key environmental issues and future challenges to the wider public.

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.

This international rigorously peer-reviewed volume critically synthesizes current knowledge in forest hydrology and biogeochemistry. It is a one-stop comprehensive reference tool for researchers and practitioners in the fields of hydrology, biogeoscience, ecology, forestry, boundary-layer meteorology, and geography. Following an introductory chapter tracing the historical roots of the subject, the book is divided into the following main sections: · Sampling and Novel Approaches · Forest Hydrology and Biogeochemistry by Ecoregion and Forest Type · Hydrologic and Biogeochemical Fluxes from the Canopy to the Phreatic Surface · Hydrologic and Biogeochemical Fluxes in Forest Ecosystems: Effects of Time, Stressors, and Humans The volume concludes with a final chapter that reflects on the current state of knowledge and identifies some areas in need of further research.