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Plant root growth: An ecological perspective
TREE iol.
7, no. 10, October
1992
logical research has apparently provided little guidance to the practical science of monitoring in the past two decades. Numerous recent conferences and workshops have pointed to the need for long-term monitoring of ecological systems for understanding the effects of global environmental change, but have often been vague about the methodology and even the state variables to be used in such monitoring. The development of a more general science of monitoring, as Spellerberg envisions, presents ecologists with a straightforward but difficult challenge: what exactly do we measure about an ecological system, how do we measure it, and how will the data be used? Agreement on the best answers to these questions will not be easy to
Root Dynamics Plant Root Growth: An Ecological edited by Scientific Publications Ecological 7997. f49.50 0 632 02757
Perspective
D. Atkinson, Blackwell Publications (Special Series of the British Society Number IO), (x + 478 pages) ISBN 6
Plant roots are a problematic research topic. Roots dynamically interact with a highly complex biological, chemical and physical environment that varies in time and space, and that is uniquely unsuited to observation and manipulation. Although roots have been studied for a century or more, they are poorly understood. Interest in roots has recently grown, along with an appreciation of edaphic constraints to plant growth and the recognition that roots are primary determinants of plant fitness, biogeochemical cycling and vegetation dynamics. This book, a collection of 29 articles from a 1988 symposium, addresses the role of roots in vegetation dynamics, focusing on methodology, root function in ecologically important species and root properties influencing fitness and competition. Rather than attempt a comprehensive treatment of these topics in one volume, the book aims to stimulate interest in root biology and identify areas in need of further exploration. A dominant paradigm in root ecology holds that plants are economically astute and seek to optimize resource capture against the ‘costs’
achieve. Standardization of variables, methods and models is essential to allow comparisons and integration monitoring among results from around the world, but reduces the flexibility and detail possible in any specific system or site. To monitor effectively the consequences of human activities for natural ecological diversity at regional and global scales, however, may require a reduction in the diversity of our scientific approaches to monitoring ecological systems.
followed by arid ecosystems, and a single chapter is devoted to the tundra. Several of these chapters successfully integrate complex phenomena in the context of clearly defined adaptive strategies, validated by cost-benefit analysis. Nobel, Caldwell and colleagues present a convincing view of desert roots, which exploit deep soil water as well as superficial flushes from brief rains at minimal carbon cost. The picture that emerges of grasslands is less straightforward, in part because of the number of viewpoints presented. Notably lacking is any significant treatment of forests, or tropical systems, which present Joel G. Kingsolver different challenges and opportuniMark S. Wells ties to roots. Water is a critical resource in both OeptofZoology, University ofWashington, Seattle,WA 98195,USA arctic and desert ecosystems, and nitrogen is a primary limitation in British grasslands. Much of the discussion is therefore focused on water and nitrogen as soil resources, whereas in a global context availability of phosphorus and base of soil exploration. Existing methelements (calcium, magnesium, ods, as reviewed in this book, generpotassium) may be at least as ally fail to meet the challenge imimportant, especially in the tropics. plicit in this paradigm of measuring This distinction may have fundaroot activity in four dimensions. The mental importance since both water approach developed by Fitter of and nitrogen are tightly linked with quantifying two-dimensional root plant photosynthetic capacity and system architecture, and the more thereby carbon economy, whereas spatially and temporally explicit the link between carbon economy studies of Nobel and colleagues on and other nutrients is considerably carbon allocation and water capture more remote. Mycorrhizal symbioses, in desert plants, represent pioneerwhich receive relatively little attening approaches to this problem, tion in this volume, are also of deserving of more thorough disgreater relevance to the acquisition cussion from a methodological perof immobile resources such as spective. In reviewing standard phosphorus rather than the relatively methods the book skirts emerging mobile water and nitrogen. The techniques and problematic methfocus on just a few ecosystems, odological issues (such as the while indicative of existing biases in choice of appropriate economic curresearch effort, may limit the genrencies, statistical sophisticated eral utility of this book. approaches to soil heterogeneity deA chapter by Grime on the ‘foragveloped by agricultural researchers, ing ability’ of roots in response to computer modeling, the overtly telespatial and temporal nutrient patches, ological nature of current models, as a determinant of competitive fittrade-offs between precision and ness, stands out as a useful experrealism, the need for experimental imental approach. Grime emphasizes manipulation of systems through growth rate and tissue turnover in the use of artificial soils, root graftforaging ability, as an extension of ing, use of genetic mutants lacking his triangular model of competition/ root hairs, etc.) and the need to stress-tolerator/ruderal plant stratmove beyond merely observational studies and comparisons of widely egies. Plasticity of root response to different plant types. In this regard localized nutrient resources may not the book is a useful overview of be as important as total root producwhat is being done, but in general, it tion rate in determining fitness. This is unlikely to contribute to the develchapter serves as a reminder of the opment of the new approaches that need for experimental manipulation are needed in root biology. to verify theory, and also of the Another group of articles coninadequacy of existing methods, siders root function in selected ecosince the patches and pulses emsystems. Grassland and pasture ecoployed bear little relation to nutrient systems receive the main emphasis, availability in natural systems. 355
books
TREE vol. 7, no. IO, October
In conclusion, the book summarizes the views of many of the leaders in root ecology, and in this capacity is a useful introduction to the field. It does not advance the field as much as hoped, because of an unimaginative treatment of methodological issues, a tantalizing yet inconsistent treatment of root function (more successfully addressed in another recent book’) and - with a few notable exceptions - insufficient
emphasis on integration and synthesis. Indeed, the book accurately mirrors the weaknesses of root ecology as a discipline. At its best it probes towards a more incisive view of roots as determinants of plant fitness, competition and vegetation dynamics, but with obvious obstacles in the road ahead. If the difficulty and promise of root biology enlist the efforts of a few more courageous souls to root research,
the book will have fulfilled important objective.
1992
its most
Jonathan lynch Sieglinde Snapp Deptof Horticulture,The PennsylvaniaState University,UniversityPark,PA 16802,USA Reference 1 Waisel, Y., Eshel, A. and Kafkafi, U.,
eds (1991) Plant Roots: The Hidden /-/a/f, Marcel Dekker
Sulphurin the Environment Sulphur Cycling on the Continents: Wetlands, Terrestrial Ecosystems and Associated Water Bodies (Scope 48) edited by R.W. Howarth, J.W.B. Stewart and M.V. Ivanov, John Wiley, 1992. f75.00 hbk (xx + 350 pages) ISBN 0 47193153 5 This publication comes from The International Sulphur Unit of The Scientific Committee on Problems of the Environment (SCOPE). It is a collection of chapters produced by contributors to a UNEP/SCOPE workshop held in Canada (1989) together with some material from related meetings held in The Netherlands (1987) and the USSR (1988), all of which have been updated, with references as recent as 1991. It is a quality production by the experts and will be a source reference for some years to come. One has to say it - the scope of this book is enormous. It brings together information on sulphur cycling in a variety of continental ecosystems, embracing everything from the atmosphere, wetlands, marine and freshwater systems to agricultural and forestry soils. It combines biology, microbiology, chemistry, biochemistry, geochemistry, methodology and mathematical modelling in a comprehensive, international, interdisciplinary overview of the oxidation and reduction of inorganic and organic sulphur. It provides useful current information for those interested in particular aspects of the global sulphur cycle, as well as for the general environmental scientist. As a specialist (microbiologist) worker in the field of sulphur cycling, it has long been a source of irritation and inconvenience to find that so much of the relevant reference material is often scattered through disparate journals and books - retrieval can be difficult, if not impossible to achieve. It is
therefore a pleasure to read a book with such a diversity of information in one place. The book provides both a good read and is easy to use for reference. The contents section lists the chapters with subdivision titles allowing the reader to dip in at points of interest. The Index is fairly comprehensive although marred by a number of spelling mistakes, some of which are unforgiveable. Each (peerviewed) chapter is well referenced and there is liberal use of diagrams, graphs and tables which will be of use to both teachers and researchers. Some chapters have an appendix containing supplementary evidence and information resulting from discussions by other contributors to the workshops. There is also much cross-referencing with previous SCOPE publications. The study of the global sulphur cycle has been driven in recent years by the increasing awareness of the occurrence and effects of anthropogenic sulphur emissions. Ironically, these studies have served to improve our understanding of the vast scale of biogenic sulphur emissions and subsequent cycling. It is only in the last 20 years that hydrogen sulphide has lost its pre-
eminent position as the dominant atmospheric sulphur gas, and the increasing knowledge of the impottante of organic sulphur gases in biogenic sulphur cycling is reflected in this book. Future progress in this area of research is probably ratelimited by the analytical problems in the field (which are discussed), together with nasal sensitivities and safety precautions in laboratories, which are politely ignored. All sections of the book provide the latest available information but also pose many unanswered questions in a field of research where clearly much remains to be done. It is an exciting area of research that has significance for all of us, be it sulphur depletion of agricultural soils or acid rain damage to vegetation and soils. There has been an explosion of publications in this area in the last five years which leads me to hope that this will not be the last workshop nor the last book of this type, but it certainly rates as one of the best to date.
Ann Wood Divisionof BiosphereSciences,King’sCollege London,Universityof London,CampdenHill Road,London,UKWE7AH
-Biology and Geomorphology of Saltmarsh& Saltmarshes: Morphodynamics, Conservation and Engineering Significance edited by J.R.L. Allen and K. Pye, Cambridge University Press, 7992. f24.95/$49.95 hbk (viii + 184 pages) ISBN 0521418410 The literature on voluminous. Many classics of ecological
saltmarshes is of the early writing refer to
saltmarshes, and field work in saltmarshes continues to be a feature of many undergraduate courses. Is yet another addition to the literature justified? After reading Saltmarshes the answer has to be a firm ‘yes’. What comes over very clearly is that despite decades of research many and physical basic biological processes are still poorly understood. At least from a botanical
7, no. 10, October
1992
logical research has apparently provided little guidance to the practical science of monitoring in the past two decades. Numerous recent conferences and workshops have pointed to the need for long-term monitoring of ecological systems for understanding the effects of global environmental change, but have often been vague about the methodology and even the state variables to be used in such monitoring. The development of a more general science of monitoring, as Spellerberg envisions, presents ecologists with a straightforward but difficult challenge: what exactly do we measure about an ecological system, how do we measure it, and how will the data be used? Agreement on the best answers to these questions will not be easy to
Root Dynamics Plant Root Growth: An Ecological edited by Scientific Publications Ecological 7997. f49.50 0 632 02757
Perspective
D. Atkinson, Blackwell Publications (Special Series of the British Society Number IO), (x + 478 pages) ISBN 6
Plant roots are a problematic research topic. Roots dynamically interact with a highly complex biological, chemical and physical environment that varies in time and space, and that is uniquely unsuited to observation and manipulation. Although roots have been studied for a century or more, they are poorly understood. Interest in roots has recently grown, along with an appreciation of edaphic constraints to plant growth and the recognition that roots are primary determinants of plant fitness, biogeochemical cycling and vegetation dynamics. This book, a collection of 29 articles from a 1988 symposium, addresses the role of roots in vegetation dynamics, focusing on methodology, root function in ecologically important species and root properties influencing fitness and competition. Rather than attempt a comprehensive treatment of these topics in one volume, the book aims to stimulate interest in root biology and identify areas in need of further exploration. A dominant paradigm in root ecology holds that plants are economically astute and seek to optimize resource capture against the ‘costs’
achieve. Standardization of variables, methods and models is essential to allow comparisons and integration monitoring among results from around the world, but reduces the flexibility and detail possible in any specific system or site. To monitor effectively the consequences of human activities for natural ecological diversity at regional and global scales, however, may require a reduction in the diversity of our scientific approaches to monitoring ecological systems.
followed by arid ecosystems, and a single chapter is devoted to the tundra. Several of these chapters successfully integrate complex phenomena in the context of clearly defined adaptive strategies, validated by cost-benefit analysis. Nobel, Caldwell and colleagues present a convincing view of desert roots, which exploit deep soil water as well as superficial flushes from brief rains at minimal carbon cost. The picture that emerges of grasslands is less straightforward, in part because of the number of viewpoints presented. Notably lacking is any significant treatment of forests, or tropical systems, which present Joel G. Kingsolver different challenges and opportuniMark S. Wells ties to roots. Water is a critical resource in both OeptofZoology, University ofWashington, Seattle,WA 98195,USA arctic and desert ecosystems, and nitrogen is a primary limitation in British grasslands. Much of the discussion is therefore focused on water and nitrogen as soil resources, whereas in a global context availability of phosphorus and base of soil exploration. Existing methelements (calcium, magnesium, ods, as reviewed in this book, generpotassium) may be at least as ally fail to meet the challenge imimportant, especially in the tropics. plicit in this paradigm of measuring This distinction may have fundaroot activity in four dimensions. The mental importance since both water approach developed by Fitter of and nitrogen are tightly linked with quantifying two-dimensional root plant photosynthetic capacity and system architecture, and the more thereby carbon economy, whereas spatially and temporally explicit the link between carbon economy studies of Nobel and colleagues on and other nutrients is considerably carbon allocation and water capture more remote. Mycorrhizal symbioses, in desert plants, represent pioneerwhich receive relatively little attening approaches to this problem, tion in this volume, are also of deserving of more thorough disgreater relevance to the acquisition cussion from a methodological perof immobile resources such as spective. In reviewing standard phosphorus rather than the relatively methods the book skirts emerging mobile water and nitrogen. The techniques and problematic methfocus on just a few ecosystems, odological issues (such as the while indicative of existing biases in choice of appropriate economic curresearch effort, may limit the genrencies, statistical sophisticated eral utility of this book. approaches to soil heterogeneity deA chapter by Grime on the ‘foragveloped by agricultural researchers, ing ability’ of roots in response to computer modeling, the overtly telespatial and temporal nutrient patches, ological nature of current models, as a determinant of competitive fittrade-offs between precision and ness, stands out as a useful experrealism, the need for experimental imental approach. Grime emphasizes manipulation of systems through growth rate and tissue turnover in the use of artificial soils, root graftforaging ability, as an extension of ing, use of genetic mutants lacking his triangular model of competition/ root hairs, etc.) and the need to stress-tolerator/ruderal plant stratmove beyond merely observational studies and comparisons of widely egies. Plasticity of root response to different plant types. In this regard localized nutrient resources may not the book is a useful overview of be as important as total root producwhat is being done, but in general, it tion rate in determining fitness. This is unlikely to contribute to the develchapter serves as a reminder of the opment of the new approaches that need for experimental manipulation are needed in root biology. to verify theory, and also of the Another group of articles coninadequacy of existing methods, siders root function in selected ecosince the patches and pulses emsystems. Grassland and pasture ecoployed bear little relation to nutrient systems receive the main emphasis, availability in natural systems. 355
books
TREE vol. 7, no. IO, October
In conclusion, the book summarizes the views of many of the leaders in root ecology, and in this capacity is a useful introduction to the field. It does not advance the field as much as hoped, because of an unimaginative treatment of methodological issues, a tantalizing yet inconsistent treatment of root function (more successfully addressed in another recent book’) and - with a few notable exceptions - insufficient
emphasis on integration and synthesis. Indeed, the book accurately mirrors the weaknesses of root ecology as a discipline. At its best it probes towards a more incisive view of roots as determinants of plant fitness, competition and vegetation dynamics, but with obvious obstacles in the road ahead. If the difficulty and promise of root biology enlist the efforts of a few more courageous souls to root research,
the book will have fulfilled important objective.
1992
its most
Jonathan lynch Sieglinde Snapp Deptof Horticulture,The PennsylvaniaState University,UniversityPark,PA 16802,USA Reference 1 Waisel, Y., Eshel, A. and Kafkafi, U.,
eds (1991) Plant Roots: The Hidden /-/a/f, Marcel Dekker
Sulphurin the Environment Sulphur Cycling on the Continents: Wetlands, Terrestrial Ecosystems and Associated Water Bodies (Scope 48) edited by R.W. Howarth, J.W.B. Stewart and M.V. Ivanov, John Wiley, 1992. f75.00 hbk (xx + 350 pages) ISBN 0 47193153 5 This publication comes from The International Sulphur Unit of The Scientific Committee on Problems of the Environment (SCOPE). It is a collection of chapters produced by contributors to a UNEP/SCOPE workshop held in Canada (1989) together with some material from related meetings held in The Netherlands (1987) and the USSR (1988), all of which have been updated, with references as recent as 1991. It is a quality production by the experts and will be a source reference for some years to come. One has to say it - the scope of this book is enormous. It brings together information on sulphur cycling in a variety of continental ecosystems, embracing everything from the atmosphere, wetlands, marine and freshwater systems to agricultural and forestry soils. It combines biology, microbiology, chemistry, biochemistry, geochemistry, methodology and mathematical modelling in a comprehensive, international, interdisciplinary overview of the oxidation and reduction of inorganic and organic sulphur. It provides useful current information for those interested in particular aspects of the global sulphur cycle, as well as for the general environmental scientist. As a specialist (microbiologist) worker in the field of sulphur cycling, it has long been a source of irritation and inconvenience to find that so much of the relevant reference material is often scattered through disparate journals and books - retrieval can be difficult, if not impossible to achieve. It is
therefore a pleasure to read a book with such a diversity of information in one place. The book provides both a good read and is easy to use for reference. The contents section lists the chapters with subdivision titles allowing the reader to dip in at points of interest. The Index is fairly comprehensive although marred by a number of spelling mistakes, some of which are unforgiveable. Each (peerviewed) chapter is well referenced and there is liberal use of diagrams, graphs and tables which will be of use to both teachers and researchers. Some chapters have an appendix containing supplementary evidence and information resulting from discussions by other contributors to the workshops. There is also much cross-referencing with previous SCOPE publications. The study of the global sulphur cycle has been driven in recent years by the increasing awareness of the occurrence and effects of anthropogenic sulphur emissions. Ironically, these studies have served to improve our understanding of the vast scale of biogenic sulphur emissions and subsequent cycling. It is only in the last 20 years that hydrogen sulphide has lost its pre-
eminent position as the dominant atmospheric sulphur gas, and the increasing knowledge of the impottante of organic sulphur gases in biogenic sulphur cycling is reflected in this book. Future progress in this area of research is probably ratelimited by the analytical problems in the field (which are discussed), together with nasal sensitivities and safety precautions in laboratories, which are politely ignored. All sections of the book provide the latest available information but also pose many unanswered questions in a field of research where clearly much remains to be done. It is an exciting area of research that has significance for all of us, be it sulphur depletion of agricultural soils or acid rain damage to vegetation and soils. There has been an explosion of publications in this area in the last five years which leads me to hope that this will not be the last workshop nor the last book of this type, but it certainly rates as one of the best to date.
Ann Wood Divisionof BiosphereSciences,King’sCollege London,Universityof London,CampdenHill Road,London,UKWE7AH
-Biology and Geomorphology of Saltmarsh& Saltmarshes: Morphodynamics, Conservation and Engineering Significance edited by J.R.L. Allen and K. Pye, Cambridge University Press, 7992. f24.95/$49.95 hbk (viii + 184 pages) ISBN 0521418410 The literature on voluminous. Many classics of ecological
saltmarshes is of the early writing refer to
saltmarshes, and field work in saltmarshes continues to be a feature of many undergraduate courses. Is yet another addition to the literature justified? After reading Saltmarshes the answer has to be a firm ‘yes’. What comes over very clearly is that despite decades of research many and physical basic biological processes are still poorly understood. At least from a botanical