- Email: [email protected]
Tropical forests and climate
294
Forest Ecology and Management 65 (1994) 293-299
terms of soil infiltration rates and their possible impact on extreme river flows were not considered. Overall, this is a very valuable text which will be of particular interest to those foresters, scientists and policy makers involved with the Eucalyptus controversy. Although a number of the papers have already been published in scientific journals, this book has the advantage of provid-
ing the complete story. The book is well produced and at £45 is good value for money. THOMAS R. NISBET
Environmental Research Branch ForestryAuthority Research Station Alice Holt Lodge Farnham Surrey GUIO4LH UK
SSDIO378-1127(93)O3328-G
Tropical forests and climate
Tropical Forests and Climate. Edited by N. Myers. Reprinted from Climatic Change 19 (1-2), 1991. Kluwer Academic Publishers, Dordrecht, Netherlands, 1992, 265 pp., price US$112.00, ISBN 0-792-31688-6. This fine review of the present status of tropical forests and climatic changes does not miss a single point, this is the impression the reader gets from just looking at the table of contents. Issues now almost traditionally controversial, such as the influence of deforestation on atmospheric carbon dioxide and on hydrologic processes, and the implementation of alternatives such as fastgrowing tropical plantations to offset the build up of carbon dioxide, are all well balanced by commentaries that bring the subjects into perspective. However, the book covers much more than that. It starts with an exhaustive review of the present status and future outlook on tropical forests by the editor himself: with a focus on the three 'key countries' which hold more than 50% of the remaining tropical forests: Brazil; Zaire and Indonesia. The author discusses the current available figures for deforestation and points out potential inaccuracies in the data. The author stresses that deforestation is seldom compensated by regrowth, as many of the deforested lands are used for agriculture or cattle; also, after abandonment, regrowth generally occurs very slowly if at all, because of a number of constraints to natural regeneration. This points to an
area of research for ecologists and foresters: mechanisms driving natural forest regeneration and ways to accelerate these processes. The author stresses the role of 'shifted cultivation' i.e., presumably practiced by people who would not be farmers, given the choice, in contrast to 'shifting cultivation', practiced in a more 'traditional' fashion. Shifted cultivation apparently accounts for 35, 50 and 70% of deforestation of closed forests in America, Asia and Africa, respectively, yet most policies to halt deforestation have so far been directed to controlling other activities such as logging, road building or cattle ranching. This almost expected opening chapter is followed by three contributions on the effects of past climatic changes on vegetation of the Neotropics, Asia and Africa. Although not as directly relevant to the present day issue of climatic changes and deforestation, since it is difficult to think how we can extrapolate late quaternary phenomena to the present time, they are indeed extremely interesting scientifically and they do point to the severe effects that climatic changes may have on biodiversity. It is also nice to see here, as well as in the remainder of the book, how the editor succeeded in bringing in a global perspective by including contributions on the three main land masses that support tropical vegetation, without exclusively focusing on one region such as the Amazon. An excellent review of the effects of deforestation on atmospheric carbon dioxide follows: data from the first chapter are used in calculations of the net flux of carbon to the atmosphere. This connection between chapters
Forest Ecology and Management 65 (1994) 293-299
makes the whole book read smoothly, which is often not the case in books which gather sets of individual contributions. The author points to the uncertainties in the existing data, for example, is all the area under shifting cultivation being used, so that vegetation (crops or trees) may take up some of the carbon? In spite of the uncertainties, the estimated emissions are of such a magnitude that halting deforestation will have a much larger effect on atmospheric carbon than any large-scale reforestation efforts. The chapter on effects on atmospheric chemistry brings in a particularly interesting topic: gaseous emissions could stimulate photochemistry, leading to enhanced ozone production and higher acidity in rainfall in agricultural areas. Good case studies from Asia, Africa and tropical America illustrate impacts of deforestation on amounts and distribution of rainfall, which although only at the level of a correlation can indeed be indicative enough of potential and substantial changes. Effects of climatic changes on crop productivity are discussed in only one chapter; there are much more research data available on the theme these days. Finally, among the management solutions proposed, reforestation of 1 to 2 million ha in tropical regions worldwide is called for. Although the authors of this chapter acknowledge the principal constraints to such a reforestation effort, they still
295
fall short in not putting enough emphasis on the significant lack of scientific and practical experience with large-scale reforestation: data on plantation growth available in the literature comes from a few favorable sites (where plantations could indeed grow and thus produce growth data) but many areas 'available' for reforestation have been heavily used for agriculture or pasture and are compacted, eroded and nutrientpoor. This calls again for more knowledge on species' adaptability to poor site conditions, management, seed production and other biological aspects, as well as on the economic, social and cultural aspects involved. The authors seem to put too much credit on the past successes with crops by the Green Revolution, assuming that similar experiences with high yields and genetic improvement can be obtained with trees. The book closes with chapters dealing with policy alternatives to decrease or offset gas emissions, and controlling land uses to halt deforestation in tropical countries. The book is a useful reference material for those concerned with the scientific aspects regarding deforestation and climate changes. FLORENCIA MONTAGNINI
Yale University School of Forestry and Environmental Studies New Haven, CT06511 USA
SSDIO378-1127(93)O3325-D
Plantation forestry in the tropics Plantation Forestry in the Tropics. 2nd ed. by J. Evans. Oxford Science Publications/Clarendon Press, Oxford, 1992, 403 pp., price £30.00, ISBN 0-198-54257-7. The second edition of Plantation Forestry in the Tropics contains advanced contributions on subjects relating to tree planting for industrial, social, environmental, and agroforestry purposes in the tropics. There was a great increase in the demand for
wood products in the tropics over the last decade. In order to supply this demand there was a need to increase planted areas and productivity, which in turn was reflected in advanced silvicultural techniques. This increasing technology motivated the author to review the original book as an aid to bringing it up-to-date, by including information on the advances in forest science over the last ten years in the tropics. The structure of the book was maintained, however, each chapter was enriched with discussions including many recent references. The introductory chapters describe the major
Forest Ecology and Management 65 (1994) 293-299
terms of soil infiltration rates and their possible impact on extreme river flows were not considered. Overall, this is a very valuable text which will be of particular interest to those foresters, scientists and policy makers involved with the Eucalyptus controversy. Although a number of the papers have already been published in scientific journals, this book has the advantage of provid-
ing the complete story. The book is well produced and at £45 is good value for money. THOMAS R. NISBET
Environmental Research Branch ForestryAuthority Research Station Alice Holt Lodge Farnham Surrey GUIO4LH UK
SSDIO378-1127(93)O3328-G
Tropical forests and climate
Tropical Forests and Climate. Edited by N. Myers. Reprinted from Climatic Change 19 (1-2), 1991. Kluwer Academic Publishers, Dordrecht, Netherlands, 1992, 265 pp., price US$112.00, ISBN 0-792-31688-6. This fine review of the present status of tropical forests and climatic changes does not miss a single point, this is the impression the reader gets from just looking at the table of contents. Issues now almost traditionally controversial, such as the influence of deforestation on atmospheric carbon dioxide and on hydrologic processes, and the implementation of alternatives such as fastgrowing tropical plantations to offset the build up of carbon dioxide, are all well balanced by commentaries that bring the subjects into perspective. However, the book covers much more than that. It starts with an exhaustive review of the present status and future outlook on tropical forests by the editor himself: with a focus on the three 'key countries' which hold more than 50% of the remaining tropical forests: Brazil; Zaire and Indonesia. The author discusses the current available figures for deforestation and points out potential inaccuracies in the data. The author stresses that deforestation is seldom compensated by regrowth, as many of the deforested lands are used for agriculture or cattle; also, after abandonment, regrowth generally occurs very slowly if at all, because of a number of constraints to natural regeneration. This points to an
area of research for ecologists and foresters: mechanisms driving natural forest regeneration and ways to accelerate these processes. The author stresses the role of 'shifted cultivation' i.e., presumably practiced by people who would not be farmers, given the choice, in contrast to 'shifting cultivation', practiced in a more 'traditional' fashion. Shifted cultivation apparently accounts for 35, 50 and 70% of deforestation of closed forests in America, Asia and Africa, respectively, yet most policies to halt deforestation have so far been directed to controlling other activities such as logging, road building or cattle ranching. This almost expected opening chapter is followed by three contributions on the effects of past climatic changes on vegetation of the Neotropics, Asia and Africa. Although not as directly relevant to the present day issue of climatic changes and deforestation, since it is difficult to think how we can extrapolate late quaternary phenomena to the present time, they are indeed extremely interesting scientifically and they do point to the severe effects that climatic changes may have on biodiversity. It is also nice to see here, as well as in the remainder of the book, how the editor succeeded in bringing in a global perspective by including contributions on the three main land masses that support tropical vegetation, without exclusively focusing on one region such as the Amazon. An excellent review of the effects of deforestation on atmospheric carbon dioxide follows: data from the first chapter are used in calculations of the net flux of carbon to the atmosphere. This connection between chapters
Forest Ecology and Management 65 (1994) 293-299
makes the whole book read smoothly, which is often not the case in books which gather sets of individual contributions. The author points to the uncertainties in the existing data, for example, is all the area under shifting cultivation being used, so that vegetation (crops or trees) may take up some of the carbon? In spite of the uncertainties, the estimated emissions are of such a magnitude that halting deforestation will have a much larger effect on atmospheric carbon than any large-scale reforestation efforts. The chapter on effects on atmospheric chemistry brings in a particularly interesting topic: gaseous emissions could stimulate photochemistry, leading to enhanced ozone production and higher acidity in rainfall in agricultural areas. Good case studies from Asia, Africa and tropical America illustrate impacts of deforestation on amounts and distribution of rainfall, which although only at the level of a correlation can indeed be indicative enough of potential and substantial changes. Effects of climatic changes on crop productivity are discussed in only one chapter; there are much more research data available on the theme these days. Finally, among the management solutions proposed, reforestation of 1 to 2 million ha in tropical regions worldwide is called for. Although the authors of this chapter acknowledge the principal constraints to such a reforestation effort, they still
295
fall short in not putting enough emphasis on the significant lack of scientific and practical experience with large-scale reforestation: data on plantation growth available in the literature comes from a few favorable sites (where plantations could indeed grow and thus produce growth data) but many areas 'available' for reforestation have been heavily used for agriculture or pasture and are compacted, eroded and nutrientpoor. This calls again for more knowledge on species' adaptability to poor site conditions, management, seed production and other biological aspects, as well as on the economic, social and cultural aspects involved. The authors seem to put too much credit on the past successes with crops by the Green Revolution, assuming that similar experiences with high yields and genetic improvement can be obtained with trees. The book closes with chapters dealing with policy alternatives to decrease or offset gas emissions, and controlling land uses to halt deforestation in tropical countries. The book is a useful reference material for those concerned with the scientific aspects regarding deforestation and climate changes. FLORENCIA MONTAGNINI
Yale University School of Forestry and Environmental Studies New Haven, CT06511 USA
SSDIO378-1127(93)O3325-D
Plantation forestry in the tropics Plantation Forestry in the Tropics. 2nd ed. by J. Evans. Oxford Science Publications/Clarendon Press, Oxford, 1992, 403 pp., price £30.00, ISBN 0-198-54257-7. The second edition of Plantation Forestry in the Tropics contains advanced contributions on subjects relating to tree planting for industrial, social, environmental, and agroforestry purposes in the tropics. There was a great increase in the demand for
wood products in the tropics over the last decade. In order to supply this demand there was a need to increase planted areas and productivity, which in turn was reflected in advanced silvicultural techniques. This increasing technology motivated the author to review the original book as an aid to bringing it up-to-date, by including information on the advances in forest science over the last ten years in the tropics. The structure of the book was maintained, however, each chapter was enriched with discussions including many recent references. The introductory chapters describe the major