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Agroforestry: Principles and practice
Landscapeand Urban Planning, 27 (1993) 41-52 Elsevier Science Publishers B.V., Amsterdam
47
Book Reviews
Agroforestry: principles and practice Agroforestry: Principles and Practice, P.G. Jarvis (Editor), Elsevier, Amsterdam, 199 1, 356 pp., US $138SO/Dfl. 175, ISBN 0-44489376-8. Although ancient in origin, the practice of agroforestry has only recently begun to gain international attention. This increased visibility has resulted in part from the growing understanding of the urgency for development of agricultural and forestry systems that can be sustained over long periods. Several international conferences have been held, including one in 1989 at Washington State University, reported in the volume titled Planning fir Agrofirestry, that dealt primarily with land use planning in the tropics. (See review by H.G. Schabel in this journal Vol. 21(3): 228-229.) The book reviewed here reports on a second International Conference also held in 1989 in Edinburgh, UK, under auspices of the International Union of Forest Research Organizations, the University of Edinburgh and the International Forest Science Consultancy. The purpose of the conference was to appraise the present state of knowledge on agroforestry and to examine problems of implementation from the perspective of scientists and land managers. The 26 papers included were initially published in Forest Ecology and Management Vol. 45 ( 199 1). The role of the forest component in various agroforestry systems received major emphasis. The research reported came from regions as different as Scotland, Nigeria, Sri Lanka, New Zealand, and the Phillipines. In an initial overview chapter, P.K.R. Nair emphasizes the early origins of the art of agroforestry, and states that it is the science which is new; research on these systems had hardly
begun before the 1980’s. Several of the older systems and the potential for their improvement are described in later chapters. Nair defines agroforestry as a collective term for “. . land-use systems involving trees combined with crops and/or animals on the same unit of land”. He lists ten agrosilvicultural systems, three silvopastoral systems and five agrosilvopastoral systems. These are described, and their values and potential noted. Specific studies throughout the volume extend his analysis. In Nair’s opinion, scientific management is essential to obtain maximum benefits. He states, “Today’s trend in agroforestry development represents an unhealthy imbalance between vast development projects and inadequate, low levels of scientific investigation”. A wide range of research is detailed and reviewed in this volume, but the continuing need for additional information is apparent in almost every case. For example, the effects of the interception of light and rainfall as well as the canopy influence on temperature, humidity, and wind are noted, as is evidence that interception of some radiation can result in higher yields of an agricultural crop, but knowledge of the relationship of microclimate to below ground interactions is inadequate. A study comparing alley cropping and intercropping in India discusses some of the competitive relationships between crops and trees and points to the need for more information on positive and negative interactions particularly below ground. Other chapters examine subjects as diverse as runoff forestry and crop production in Israel, the relationship between conifer spacing and herbage production in the UK, the impact of agroforestry on fertility and structure of tropical soils, and the development of mathematical models to guide planning and evaluate profitability.
48
Objectives for agroforestry programs vary with the region under consideration and encompass a wide spectrum. Examples include increasing the yield and sustainability of extant techniques of shifting cultivation in the tropics, reclaiming degraded agricultural land in Europe-where a major need is to increase the timber growing potential and reduce dependence on imports or increasing productivity-and reducing erosion in arid portions of Africa and the Middle East. Properly implemented agroforestry systems can also be used to provide major social benefits as in parts of India where, in addition to food and fuel, agroforestry also serves to provide employment to the rural poor. As reported in one chapter, the net socio-economic benefits may often exceed the net financial returns. Each of these as well as other objectives are discussed in reference to specific studies. In many of the studies, authors emphasize the need for flexibility in planning and especially the importance of working with local people to understand their needs and production strategies. In total, the book illustrates well the problems inherent in developing and implementing agroforestry programs throughout the world. It also documents the considerable progress that has been made in integrating forestry into diverse agricultural systems. For anyone not familiar with developments in agroforestry (and this includes most of us), this book provides insight into the unrealized potential for sustainable production as well as the high level of complexity inherent in combining forest with crop or livestock production. The volume brings together a broad disciplinary mix with contributions from ecology, sociology, soil science, and economics in addition to forestry and agriculture while including illustrations from work in both developing and developed countries. The chapters vary considerably in length and in technical complexity and readers may not wish nor need to read all of them in detail. Certainly, both foresters and agriculturalists, groups that have tended to fo-
cus narrowly on their own disciplines, will profit from examining this book. Likewise, students as well as scientists and practitioners of many persuasions will find it enlightening. FOREST
STEARNS
Forestry Sciences Laboratory North Central Forest E_xperimentStation LSFS Rhinelander, WI 54501 us,4
Outdoor space Outdoor Dutch
Space Environments Landscape Architects
Designed by Since 1945,
Meto Vroom (Editor) Thoth, Amsterdam, 1992,208 pp. Outdoor Space is the result of an initiative of the Executive Board of the Dutch Association for Landscape Architecture in part to celebrate the organization’s 70th anniversary. The book is intended to promote the role of landscape architects in improving environmental quality and in designing new environments in The Netherlands since 1945. The book is targeted to a broad and diverse audience, ranging from those unfamiliar with landscape architecture to students and professionals in the field. The book is organized into four sections; an extended introduction, and three sections presenting categories of design and planning projects from gardens to parks to landscapes. The collective works are not presented as a comprehensive overview or catalog but rather as a collection of examples of works of older and young designers ranging from regional planning to detail design work. Throughout the book, the editor has made a conscious effort to articulate the ‘Dutch’ style in modern landscape architecture, one that responds to the unique traditions as well as the new challenges of the modern era in The Netherlands. The focus of Outdoor Space is on the post World War II period, one which saw the emergence of landscape architecture as the key
47
Book Reviews
Agroforestry: principles and practice Agroforestry: Principles and Practice, P.G. Jarvis (Editor), Elsevier, Amsterdam, 199 1, 356 pp., US $138SO/Dfl. 175, ISBN 0-44489376-8. Although ancient in origin, the practice of agroforestry has only recently begun to gain international attention. This increased visibility has resulted in part from the growing understanding of the urgency for development of agricultural and forestry systems that can be sustained over long periods. Several international conferences have been held, including one in 1989 at Washington State University, reported in the volume titled Planning fir Agrofirestry, that dealt primarily with land use planning in the tropics. (See review by H.G. Schabel in this journal Vol. 21(3): 228-229.) The book reviewed here reports on a second International Conference also held in 1989 in Edinburgh, UK, under auspices of the International Union of Forest Research Organizations, the University of Edinburgh and the International Forest Science Consultancy. The purpose of the conference was to appraise the present state of knowledge on agroforestry and to examine problems of implementation from the perspective of scientists and land managers. The 26 papers included were initially published in Forest Ecology and Management Vol. 45 ( 199 1). The role of the forest component in various agroforestry systems received major emphasis. The research reported came from regions as different as Scotland, Nigeria, Sri Lanka, New Zealand, and the Phillipines. In an initial overview chapter, P.K.R. Nair emphasizes the early origins of the art of agroforestry, and states that it is the science which is new; research on these systems had hardly
begun before the 1980’s. Several of the older systems and the potential for their improvement are described in later chapters. Nair defines agroforestry as a collective term for “. . land-use systems involving trees combined with crops and/or animals on the same unit of land”. He lists ten agrosilvicultural systems, three silvopastoral systems and five agrosilvopastoral systems. These are described, and their values and potential noted. Specific studies throughout the volume extend his analysis. In Nair’s opinion, scientific management is essential to obtain maximum benefits. He states, “Today’s trend in agroforestry development represents an unhealthy imbalance between vast development projects and inadequate, low levels of scientific investigation”. A wide range of research is detailed and reviewed in this volume, but the continuing need for additional information is apparent in almost every case. For example, the effects of the interception of light and rainfall as well as the canopy influence on temperature, humidity, and wind are noted, as is evidence that interception of some radiation can result in higher yields of an agricultural crop, but knowledge of the relationship of microclimate to below ground interactions is inadequate. A study comparing alley cropping and intercropping in India discusses some of the competitive relationships between crops and trees and points to the need for more information on positive and negative interactions particularly below ground. Other chapters examine subjects as diverse as runoff forestry and crop production in Israel, the relationship between conifer spacing and herbage production in the UK, the impact of agroforestry on fertility and structure of tropical soils, and the development of mathematical models to guide planning and evaluate profitability.
48
Objectives for agroforestry programs vary with the region under consideration and encompass a wide spectrum. Examples include increasing the yield and sustainability of extant techniques of shifting cultivation in the tropics, reclaiming degraded agricultural land in Europe-where a major need is to increase the timber growing potential and reduce dependence on imports or increasing productivity-and reducing erosion in arid portions of Africa and the Middle East. Properly implemented agroforestry systems can also be used to provide major social benefits as in parts of India where, in addition to food and fuel, agroforestry also serves to provide employment to the rural poor. As reported in one chapter, the net socio-economic benefits may often exceed the net financial returns. Each of these as well as other objectives are discussed in reference to specific studies. In many of the studies, authors emphasize the need for flexibility in planning and especially the importance of working with local people to understand their needs and production strategies. In total, the book illustrates well the problems inherent in developing and implementing agroforestry programs throughout the world. It also documents the considerable progress that has been made in integrating forestry into diverse agricultural systems. For anyone not familiar with developments in agroforestry (and this includes most of us), this book provides insight into the unrealized potential for sustainable production as well as the high level of complexity inherent in combining forest with crop or livestock production. The volume brings together a broad disciplinary mix with contributions from ecology, sociology, soil science, and economics in addition to forestry and agriculture while including illustrations from work in both developing and developed countries. The chapters vary considerably in length and in technical complexity and readers may not wish nor need to read all of them in detail. Certainly, both foresters and agriculturalists, groups that have tended to fo-
cus narrowly on their own disciplines, will profit from examining this book. Likewise, students as well as scientists and practitioners of many persuasions will find it enlightening. FOREST
STEARNS
Forestry Sciences Laboratory North Central Forest E_xperimentStation LSFS Rhinelander, WI 54501 us,4
Outdoor space Outdoor Dutch
Space Environments Landscape Architects
Designed by Since 1945,
Meto Vroom (Editor) Thoth, Amsterdam, 1992,208 pp. Outdoor Space is the result of an initiative of the Executive Board of the Dutch Association for Landscape Architecture in part to celebrate the organization’s 70th anniversary. The book is intended to promote the role of landscape architects in improving environmental quality and in designing new environments in The Netherlands since 1945. The book is targeted to a broad and diverse audience, ranging from those unfamiliar with landscape architecture to students and professionals in the field. The book is organized into four sections; an extended introduction, and three sections presenting categories of design and planning projects from gardens to parks to landscapes. The collective works are not presented as a comprehensive overview or catalog but rather as a collection of examples of works of older and young designers ranging from regional planning to detail design work. Throughout the book, the editor has made a conscious effort to articulate the ‘Dutch’ style in modern landscape architecture, one that responds to the unique traditions as well as the new challenges of the modern era in The Netherlands. The focus of Outdoor Space is on the post World War II period, one which saw the emergence of landscape architecture as the key