Biogeochemistry of a forested ecosystem

Biogeochemistry of a forested ecosystem

353 BIOGEOCHEMISTRY OF A FORESTED ECOSYSTEM Bio~geochemistry o f a Forested Ecosystem. G.E. Likens, F.H. Borman, R.S. Pierce, J.S. Eaton and N.M. Joh...

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353 BIOGEOCHEMISTRY OF A FORESTED ECOSYSTEM Bio~geochemistry o f a Forested Ecosystem. G.E. Likens, F.H. Borman, R.S.

Pierce, J.S. Eaton and N.M. Johnson. Springer Verlag, Berlin, 1977, 160 pp., ISBN 3-540-90225-2. This book, written by a team of scientists, is the synthesis of the biogeochemical studies undertaken over many years on the n o w well known Hubbard Brook, New Hampshire (U.S.A.) watershed. The details of the studies, made during the last 10 years, are the subjects of many publications from these authors. The b o o k is divided into eight chapters. Three have a general nature and deal with basic concepts of mineral cycling in forest ecosystems, site description, and comparison with other forested ecosystems studied in the world (especially in the temperate climatic zone). Each of the other five chapters is focused upon a specific point of biogeochemistry. One after the other, the various parameters of mineral cycles are studied. The hydrology of the system includes five components: precipitation, interception, evapotranspiration, stream flow and deep seepage. Precipitation chemistry and soil and stream water chemistry form another chapter and contribute to the establishment of the watershed budget. This budget also needs some investigations on weathering processes, which balance the input o u t p u t budget, and are the matter of another chapter. A last chapter is devoted to mineral cycling sensu stricto, integrating its biological and physical aspects. This chapter alone provides a total picture of the calcium and sulphur cycles. This b o o k is certainly the most complete and the most accurate work done to date on mineral cycling in forest ecosystems and in watersheds. Many of the data available are the results or the synthesis of a 10-year period of investigation. Thus, no study undertaken in the past or presently in course, is in a position to furnish so numerous and detailed results, with a high degree of generalization, as this work. This is not only the case for the global budget and balance of the water and bioelement fluxes through the watershed, but also for their monthly and yearly variations. Perhaps the ecologist would feel the biological aspects of mineral cycling appear insufficient and geochemistry plays the primary role. Thus decomposition processes, which are very important in the fluxes of bioelements, are neglected. Moreover, other biological processes such as asymbiotic fixation of gaseous nitrogen by microorganisms, for which the authors give interesting data, are not emphasized enough in the text. This is a pity, because most, though not all, of the data are available, as attested by the numerous publications issued from the Hubbard Brook project. But it seems that it was easier to publish these kinds of results, focusing on physical data, in a book rather than in a succession of articles.

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Nevertheless, this b o o k is the first one dealing as completely as possible with the mineral cycles and mineral budget in a specific ecosystem 6r watershed, and it will be of considerable interest for many scientists, foresters and teachers. M. RAPP

(Montpellier, France)

TROPICAL RAIN FORESTS: RESOURCE EXPLOITATION

Ecological Considerations and Safeguards in the Modern Use of Tropical Lowland Rain Forests as a Source o f Pulpwood: Example, the Madang Area PNG. L.J. Webb. Office of Environment and Conservation, Department of Natural Resources, Papua New Guinea, 1977, iv + 36 pp. This booklet is a consultancy report on the prospects of environmental degradation resulting from extensive forest clearance in the Madang area of Papua New Guinea, aimed at converting virtually the whole forest biomass into woodchips and pulpwood. It will be welcomed by all who are concerned for the future of the tropical rain forest, its environment and peoples. The most valuable feature of the report is that it emphasizes a conservation approach while retaining a clear perspective of the social problems associated with developing, or not developing, the tropical rain forest. Beginning with an introduction which states the formal terms of the consultancy and gives the conservation-oriented background of the author, the main b o d y of the report is divided into three sections, followed by references, figures and appendices. In the first section, 'Man and the Tropical Rain Forest', the author's intimate knowledge of the processes that determine balance in tropical rain forest ecosystems is fully displayed in discussing the w o o d and non-wood values and potentials of the forest resource. Social and cultural values of the forest that cannot readily be quantified in economic terms are also highlighted, as are the physical and biological features that make the tropical rain forest unique and important. The detailed discussion of ecological processes in this section makes the report immediately relevant to all rain forest areas and opens it to a wide readership. In the second section, titled 'Logging the Madang Forests', the author recognizes that because of the human factors involved and the changeability of these, general guidelines for land use and environmental protection are not directly applicable. He criticizes strongly the inadequate planning for size and location of reserved areas, the rate and scale of logging which exceed those by which even natural catastrophies such as landslides destroy forests, the excessive damage of soil and plants during logging operations, the method of remunerating the land owners and the general lack of economic evaluation of the implications for the land owners of the logging operations. It is made abundantly clear in this section that the entire Madang area operations were begun overhastily.