When we originally published Biogeochemistry of a Forested Ecosystem in 1977, the Hubbard Brook Ecosystem Study (HBES) had been in existence for 14 years, and we included data through 1974, or a biogeo chemical record of 11 years. Now our continuous, long-term biogeo chemical records cover more than 31 years, and there have been many changes. The most notable change, however, is that three of our coauthors on the original volume are now deceased. They are deeply missed in so many ways. In spite of the longer records, different trends, and new insights, we believe that the basic concepts and approaches we presented in 1977 represent the most valuable contribution of the original edition. They are still valid and useful, particularly for an introductory study of, or course in, biogeochemistry. Our goal in this revision is to preserve these fea tures, correct errors, and revise or eliminate misleading or ambiguous short-term data (11 years!), while maintaining approximately the original length and the modest cost.

This textbook presents a comprehensive process-oriented approach to biogeochemistry that is intended to appeal to readers who want to go beyond a general exposure to topics in biogeochemistry, and instead are seeking a holistic understanding of the interplay of biotic and environmental drivers in the cycling of elements in forested watersheds. The book is organized around a core set of ecosystem processes and attributes that collectively help to generate the whole-system structure and function of a terrestrial ecosystem. In the first nine chapters, a conceptual framework is developed based on distinct soil, microbial, plant, atmospheric, hydrologic, and geochemical processes that are integrated in the element cycling behavior of watershed ecosystems. With that conceptual foundation in place, students then proceed to the final three chapters where they are challenged to think critically about integrated element cycling patterns; roles for biogeochemical models; the likely impacts of disturbance, stress, and management on watershed biogeochemistry; and linkages among patterns and processes in watersheds experiencing novel environmental changes. Included with the text are figures, tables of comparative data, extensive literature citations, a glossary of terms, an index, and a set of 24 biogeochemical problems with answers. The problems are intended to support chapter concepts and to demonstrate how critical thinking skills, simple algebra, and thoughtful human logic can be used to solve applied problems in biogeochemistry that might be encountered by a research scientist or a resource manager. Using this book as an introduction to biogeochemistry, students will achieve a level of subject mastery and disciplinary perspective that will permit them to see and to interpret the individual components, interactions, and synergies that are represented in the dynamic element cycling patterns of watershed ecosystems.

The advent of ecosystem ecology has created great difficulties for ecologists primarily trained as biologists, since inevitably as the field grew, it absorbed components of other disciplines relatively foreign to most ecologists yet vital to the understanding of the structure and function of ecosystems. From the point of view of the biological ecologist struggling to understand the enormous complexity of the biological functions within an ecosystem, the added necessity of integrating biology with geochemis try, hydrology, micrometeorology, geomorphology, pedology, and applied sciences (like silviculture and land use management) often has appeared as an impossible requirement. Ecologists have frequently responded by limiting their perspective to biology with the result that the modeling of species interactions is sometimes considered as modeling ecosystems, or modeling the living fraction of the ecosystems is considered as modeling whole ecosystems. Such of course is not the case, since understanding the structure and function of ecosystems requires sound understanding of inanimate as well as animate processes and often neither can be under stood without the other. About 15 years ago, a view of ecology somewhat different from most then prevailing, coupled with a strong dose of naivete and a sense of exploration, lead us to believe that consideration of the inanimate side of ecosystem function rather than being just one more annoying complexity might provide exceptional advantages in the study of ecosystems. To examine this possibility, we took two steps which occurred more or less simultaneously.

The goal of this Third Edition is to update long-term data presented in earlier editions and to generate new syntheses and conclusions about the biogeochemistry of the Hubbard Brook Valley based on these longer-term data. There have been many changes, revelations, and exciting new insights generated from the longer data records. For example, the impact of acid rain peaked during the period of the HBES and is now declining. The longer-term data also posed challenges in that very marked changes in fluxes occurred in some components, such as hydrogen ion and sulfate deposition, calcium and nitrate export in stream water and biomass accumulation, during the almost 50 years of record. Thus, presenting “mean” or “average” conditions for many components for such a long period, when change was so prominent, do not make sense. In some cases, pentads or decades of time are compared to show these changes in a more smoothed and rational way for this long period. In some cases, a single period, often during periods of rapid change, such as acidification, is used to illustrate the main point(s). And, for some elements a unique mass balance approach, allowing the calculation of the Net Ecosystem Flux (NEF), is shown on an annual basis throughout the study.

Ecosystem Consequences of Soil Warming: Microbes, Vegetation, Fauna and Soil Biogeochemistry focuses on biotic and biogeochemical responses to warmer soils including plant and microbial evolution. It covers various field settings, such as arctic tundra; alpine meadows; temperate, tropical and subalpine forests; drylands; and grassland ecosystems. Information integrates multiple natural science disciplines, providing a holistic, integrative approach that will help readers understand and forecast future planetwide responses to soil warming. Students and educators will find this book informative for understanding biotic and biogeochemical responses to changing climatic conditions. Scientists from a wide range of disciplines, including soil scientists, ecologists, geneticists, as well as molecular, evolutionary and conservation biologists, will find this book a valuable resource in understanding and planning for warmer climate conditions.

"Since the early 1960s, the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire has been one of the most comprehensively studied landscapes on earth. This book highlights many of the important ecological findings amassed during the long-term research conducted there, and considers their regional, national, and global implications." -- P.2 of cover.

Based on the classic ecosystem studies at Hubbard Brook in New Hampshire, this book presents an in-depth analysis of the biogeochemistry of a terrestrial ecosystem. It synthesizes long-term data on precipitation and streamwater chemistry, hydrology and weathering, and also considers the dynamics of atmospheric gases and water as they flow through the system. Hailed as "ÄaÜ standard for ecological teaching and research for years to come", the book "bristles with unsettled questions, intriguing problems, and technical challenges". This new edition brings the 1977 volume up to date and presents the ongoing Hubbard Brook study to a new generation of ecologists. The authors have international reputations: they won the $150,000 Tyler Prize in Environmental Science in 1993, and Likens also won the $250,000 Australia Prize in 1994.