As the global climate changes, there are concomitant changes in global biological productivity. This book is devoted to the assessment of terrestrial Net Primary Productivity ("the total amount of energy acquired by green plants during photosynthesis, minus the energy lost through respiration"--APDS&T, pp. 1457). The book is comprised of three major sections. The first section is a review of the processes that operate globally to influence productivity--these are the initial conditions of any model of primary productivity. The second section is comprised of chapters that assess the contribution of particular ecosystems to global productivity. The final major section contains chapters of a synthetic nature that describe attempts to model global productivity. This book should appeal to both ecologists and environmental scientists.

Ecology at the ecosystem level has both necessitated and benefited from new methods and technologies as well as those adapted from other disciplines. With the ascendancy of ecosystem science and management, the need has arisen for a comprehensive treatment of techniques used in this rapidly-growing field. Methods in Ecosystem Science answers that need by synthesizing the advantages, disadvantages and tradeoffs associated with the most commonly used techniques in both aquatic and terrestrial research. The book is divided into sections addressing carbon and energy dynamics, nutrient and water dynamics, manipulative ecosystem experiements and tools to synthesize our understanding of ecosystems. Detailed information about various methods will help researchers choose the most appropriate methods for their particular studies. Prominent scientists discuss how tools from a variety of disciplines can be used in ecosystem science at different scales.

The period since World War II, and especially the last decade influenced by the International Biological Program, has seen enormous growth in research on the function of ecosystems. The same period has seen an exponential' rise in environmental problems including the capacity of the Earth to support man's population. The concern extends to man's effects on the "biosphere"-the film of living organisms on the Earth's surface that supports man. The common theme of ecologic research and environmental concerns is primary production the binding of sunlight energy into organic matter by plants that supports all life. Many results from the IBP remain to be synthesized, but enough data are available from that program and other research to develop a convincing sum mary of the primary production of the biosphere-the purpose of this book. The book had its origin in the parallel interests of the two editors and Gene E. Likens, which led them to prepare a symposium on the topic at the Second Biological Congress of the American Institute of Biological Sciences in Miami, Florida, October 24, 1971. Revisions of the papers presented at that symposium appear as Chapters 2, 8, 9, 10, and 15 in this book. We have added other chapters that complement this core; these include discussion and evaluation of methods for measuring productivity and regional production, current findings on tropical productivity, and models of primary productivity.

Harold A. Mooney and Richard J. Hobbs At present there is enormous concern about the changes that are occurring on the surface of the earth and in the earth's atmosphere, primarily as a result of human activities. These changes, particularly in the atmosphere, have the potential for altering the earth's habitability. International pro grams unprecedented in scope, including the International Geosphere Biosphere Program, have been initiated to describe and understand these changes. The global change program will call for coordinated measure ments on a global scale of those interactive physical and biological pro cesses that regulate the earth system. The program will rely heavily on the emerging technology of remote sensing from airborne vehicles, particularly satellites. Satellites offer the potential of continuously viewing large seg ments of the earth's surface, thus documenting the changes that are occur ring. The task, however, is not only to document global change, which will be an enormous job, but also to understand the significance of these changes to the biosphere. Effects on the biosphere may cover all spatial scales from global to local. The possibility of measuring biosphere function remot~ly and continuously from satellite imagery must be explored quickly and thoroughly in order to meet the challenge of understanding the con sequences of global change. Initial guidelines and approaches are currently being formulated (Dyer and Crossley, 1986; JOI, 1984; NAS, 1986; Rasool, 1987). There are many conceptual and technical issues that must be resolved H. A. Mooney and R. J.

To achieve goals for climate and economic growth, "negative emissions technologies" (NETs) that remove and sequester carbon dioxide from the air will need to play a significant role in mitigating climate change. Unlike carbon capture and storage technologies that remove carbon dioxide emissions directly from large point sources such as coal power plants, NETs remove carbon dioxide directly from the atmosphere or enhance natural carbon sinks. Storing the carbon dioxide from NETs has the same impact on the atmosphere and climate as simultaneously preventing an equal amount of carbon dioxide from being emitted. Recent analyses found that deploying NETs may be less expensive and less disruptive than reducing some emissions, such as a substantial portion of agricultural and land-use emissions and some transportation emissions. In 2015, the National Academies published Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration, which described and initially assessed NETs and sequestration technologies. This report acknowledged the relative paucity of research on NETs and recommended development of a research agenda that covers all aspects of NETs from fundamental science to full-scale deployment. To address this need, Negative Emissions Technologies and Reliable Sequestration: A Research Agenda assesses the benefits, risks, and "sustainable scale potential" for NETs and sequestration. This report also defines the essential components of a research and development program, including its estimated costs and potential impact.

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.

Summarises understanding of global change interactions with terrestrial ecosystems.