Nitrogen is a key element in ecosystem processes. Aspects of local and global changes in nitrogen in both undisturbed and disturbed conditions are discussed. Environmental changes caused by pollution from nitrogenous compounds and changes in landuse are also described. Organisms, plants, animals and microorganisms are all affecting nitrogen supply. Emphasis is placed on natural and anthropogenic transfer of nitrogen between ecosystems and also on the interaction of nitrogen with other bioelements.
Carbon and Nitrogen in the Terrestrial Environment is a comprehensive, interdisciplinary description of C and N fluxes between the atmosphere and the terrestrial biosphere; issues related to C and N management in different ecosystems and their implications for the environment and global climate change; and the approaches to mitigate emission of greenhouse gases. Drawing upon the most up-to-date books, journals, bulletins, reports, symposia proceedings and internet sources documenting interrelationships between different aspects of C and N cycling in the terrestrial environment, Carbon and Nitrogen in the Terrestrial Environment fills the gap left by most of the currently available books on C and N cycling. They either deal with a single element of an ecosystem, or are related to one or a few selected aspects like soil organic matter (SOM) and agricultural or forest management, emission of greenhouse gases, global climate change or modeling of SOM dynamics.
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.
This book presents a comprehensive overview of nutrient cycling processes and their importance for plant growth and ecosystem sustainability. The book combines fundamental scientific studies and devised practical approaches. It contains contributions of leading international authorities from various disciplines resulting in multidisciplinary approaches, and all chapters have been carefully reviewed. This volume will support scientists and practitioners alike.
This book looks at the sources and composition of the atmosphere and rainfall, with particular attention on acidifying components and those that affect ecosystems. It further widens the subject to look at trace metals. It includes papers on the impact of deposition on soils and forests and the recovery of the natural environment. Work on critical loads makes a contribution to understanding the degree to which deposition must be reduced to limit its impact.
Features review questions at the end of each chapter; Includes suggestions for recommended reading; Provides a glossary of ecological terms; Has a wide audience as a textbook for advanced undergraduate students, graduate students and as a reference for practicing scientists from a wide array of disciplines
Nitrogen (N) availability regulates ecosystem and structure and function, and questions regarding patterns of N availability and limitation remain central in terrestrial biogeochemistry. N enters terrestrial ecosystems via three main input pathways: biological N fixation, bedrock N weathering, and atmospheric N deposition. My dissertation addresses key uncertainties regarding these N input pathways and their interactions on ecosystem and global scales, with particular emphasis on temperate forests. Through a meta-analysis, I investigated global patterns of nutrient constraints to free-living N fixation. I showed that across diverse terrestrial ecosystems from tropical forests to the boreal, free-living N fixation is strongly suppressed by N deposition and stimulated by Mo fertilization. Additionally, free-living N fixation is stimulated by P additions in tropical forests. These findings suggest that nutrient limitation is an intrinsic property of the biochemical demands of N fixation, which has implications for understanding the causes and consequences of N limitation in coupled nutrient cycles, as well as modeling and forecasting nutrient controls over carbon-climate feedbacks. Next, I examined the interaction between free-living N fixation and bedrock N inputs in forest ecosystems in northern California and southern Oregon. I showed that forests underlain by N-rich bedrock paradoxically also exhibit higher rates of free-living N fixation. I demonstrated that these forests accumulate significantly more soil N and C, leading to increased retention of Mo and P and explaining the observed N fixation patterns. Thus, bedrock N weathering acts as an N input that is directly coupled to the forest C cycle. Finally, I investigated the influence of soil N availability on plant reliance on symbiotic N acquisition pathways, including symbiotic N fixation and mycorrhizal partnerships. I demonstrate that in N-depleted soils, many plants obtain the vast majority of their tissue N via symbiotic pathways, despite the resource cost involved. My dissertation findings highlight the importance of interactions between plants, soil nutrients, geology, and microbes in driving ecosystem and global patterns of N input pathways, and demonstrate the need for a more nuanced representation of these relationships in order to accurately represent N cycling in global models.
Inputs of nitrogen to terrestrial and aquatic ecosystems have increased several-fold over the last one hundred and fifty years, with the steepest increases during the last four decades. The expansion of fertilizer manu facture and use, the increase in fossil fuel combustion, the intensification of animal husbandry, and widespread cultivation of N2 fixing crops have all contributed to the dramatic increase in N inputs. The increase has been most rapid in Northern Hemisphere (NH) temperate ecosystems, but presently subtropical and tropical regions of Asia are also experiencing an explosive increase in N inputs to terrestrial ecosystems (W. Chameides, pers. comm. ; Galloway et al. 1996). Projected increases in N deposition for these trop ical and subtropical regions, with a high natural background of N inputs, exceed increases projected for temperate and arctic regions (Cleveland et al. submitted; Galloway et al. 1994; Holland & Lamarque 1997a). Compared to biological N fixation, N deposition is becoming a proportionately greater source of N to terrestrial and aquatic ecosystems worldwide (Vitousek et al. 1997). 6 The nitrogen contained in the atmosphere as N , 3. 9 * 10 Tg (Tg = 2 12 10 g), is the largest reservoir of N in the Earth system (Warneck 1988). However, this paper focuses on the nitrogen emissions and deposition that have been transformed from N2 into reactive forms that are biologically avail able (e. g. Vitousek et al. 1997).
This volume quantifies carbon storage in managed forest ecosystems not only in biomass, but also in all soil compartments. It investigates the interaction between the carbon and nitrogen cycles by working along a north-south transect through Europe that starts in northern Sweden, passes through a N-deposition maximum in central Europe and ends in Italy. For the first time biogeochemical processes are linked to biodiversity on a large geographic scale and with special focus on soil organisms. The accompanying CD-ROM provides a complete database of all flux, storage and species observations for modellers.
