- Email: [email protected]
Reddy KR, Hodges HF, eds. 1999. Climate change and global crop productivity. 472 pp. CAB International: Wallingford & New York. £75 (hardback).
Book Reviews topics for Mediterranean plants, especially trees, are few and far between. The last topic in the section analyses the role of Mediterranean pines as invaders in the southern hemisphere. From a European point of view, it is surprising to consider the increasing importance of Mediterranean pines, which are usually out-competed in the Mediterranean Basin by late-successional Quercus species, as alien invaders in many areas of the southern hemisphere. Part II of the book comprises nine chapters on pine forest ecosystems, although `pine forest diversity' would probably be a more accurate description of most of the topics included. There are two chapters on a mechanistic model of Aleppo pine stand dynamics, and on litter production in P. halepensis forests, which have little relation to the others. The general topic of the remaining chapters is the diversity of dierent groups of organisms in Mediterranean pine forests: seed banks, mycorrhizas, soil arthropods, phytophagous insects, birds, and small mammals. The importance given in the book (seven chapters, nearly a quarter of the book) to these studies of the diversity of very dierent kinds of organism is valuable, and also justi®ed if we take into account the fact that these Mediterranean forests are important diversity refuges for many natural Mediterranean plants and animals. These chapters vary widely in quality and focus: some are very descriptive (sometimes excessively so), while others analyse community structure and dynamics (e.g. the chapter on bird communities). I would have appreciated the latter approach to the former, but realize that it is dicult to proceed in this direction with the information available for certain groups of organisms. The third part is dedicated to ®re ecology, although this topic is partially covered in other parts of the text. This makes it a little dicult to get a complete picture of the theme because ®re or ®re eects appear throughout the book. Nevertheless, in my opinion, some of the most valuable contributions in the book occur in this section. There are three chapters on post-®re regeneration, one of P. brutia and two of P. halepensis in the west and the east Mediterranean Basin. Curiously, these two studies on P. halepensis regeneration show completely dierent patterns at the two study sites; thus the book should probably have included some interpretation. The last chapters of this section analyse pre-®re and post-®re management of burned Mediterranean pine forests. Prescribed burning, ®re prevention and silvicultural systems are some of the important management themes that are discussed in the general framework of ®re protection and post-®re recovery. Management is also the main topic of the last section of the book (and should probably be included in the title instead of `aorestation', which is a narrower and less clear term in the context of the book). There are two chapters on silvopastoral management in the west and the east Mediterranean Basin, and another on management of pine plantations, including site preparation, selection of species, planting and pest control. The ®nal chapter is on impacts of air pollution on pine forests, and introduces anthropogenic impacts on Mediterranean pine forests. This is the only study on eects, sometimes synergistic, of air and water pollutants, and pests and diseases on Mediterranean pine forests, aspects which are otherwise absent from the
133
book, probably because they have not yet been developed as clearly-established research topics in Mediterranean countries. In general terms the research reviews contained in this book are well-structured and clearly written. My main question before reading the book was whether or not it provided a comprehensive overview of the research on these important tree species. After reading it, my short answer to this question is `yes'. Of course, the book relies on the topics presented at the workshop, but it covers most of the subjects related to Mediterranean pine ecology and, to a lesser extent, management. Its contents are, on the whole, clearly and logically presented, and the various authors make good attempts to summarize issues. For this reason, it might be of great use to researchers directly involved in the study of Mediterranean forests. There are some weaknesses, or topics that should be developed further, such as the intraspeci®c variability found in the dierent processes and subjects considered in the book; there are also some themes that have not been included at all, probably because there is not enough information about them. Nevertheless, the publication of a book such as this is the best way to identify the areas in which there is a large amount of information, as opposed to those about which little is known. From my point of view, this attempt to integrate past and present information from very dierent research groups makes a valuable addition to the research literature on this subject. Javier Retana # 2001 Annals of Botany Company
doi:10.1006/anbo.2000.1306 Reddy KR, Hodges HF, eds. 1999. Climate change and global crop productivity. 472 pp. CAB International: Wallingford & New York. £75 (hardback). If, like me, you have a bookshelf groaning with tomes about climate change impacts, and an in-tray full of publishers' ¯iers for this academic year's new crop, then you will probably hesitate to buy yet another. However, if you are an agriculturalist or crop scientist and make only one purchase this year in this subject area, then this should certainly be your choice. The book is an authoritative and comprehensive review of all aspects of the eects of anthropogenic climate change on crop growth, with 21 chapters provided by some 50 hugely experienced contributors. After setting the scene of what atmospheric and climate changes are likely, and what evidence there is for climate change, the ®rst section goes on to include a useful assessment of agricultural contribution to climate change, something that is often overlooked by crop scientists preoccupied with increasing productivity. The nextÐand longestÐsection then covers, in separate chapters, the major grain crops (wheat, rice, maize and sorghum), a major legume crop (soybean), tuber and root crops, vegetable crops, grassland and rangeland, timber and even CAM metabolism crops. This section then discusses cropweed interactions, pests and soil organic matter
134
Book Reviews
changes, and includes an additional chapter on the interactions of various environmental changes including UV-B and ozone. The last two sections deal with mitigation strategies such as breeding and biotechnology, and the economic and social impacts of change on global, regional and local food production and trade. There is little that can be faulted in the individual chapters, which are generally concise and usefully critical assessments of the current understanding. Many emphasize recent work, which is valuable in a fast-expanding subject. It might be felt that the subject of high CO2 , and plant growth in particular, is over-reviewed and hardly merits another volume. However, the bene®ts of this book are the comprehensive subject coverage and that the authors have been well-instructed by the editors to review climate change widely, and to consider in particular temperature and water status eects in addition to the `CO2 eect' on their particular subject material. Each chapter also concludes with a consideration of how changes might be mitigated, for example by crop breeding, or by agronomy and management. Many of the speci®c crop chapters are excellent examples of the fundamental integration of genetic, cellular, whole plant and environmental science that is the distinguishing feature of crop science. The other chapters give an essential context to the crop science details, and remind the reader of the environmental and economic aspects. The book will therefore be useful to all specialist climate change or agricultural researchers, and will be a valuable reference text for post graduate courses in these areas. A minor problem is that there is some variation in how up-to-date the chapters are ( for example the important ®nal chapter on food production and trade uses population projections from 1994, which have been signi®cantly revised since), but in general the editing has achieved a wellintegrated common format and style, and the production quality is excellent. A criticism that should be levelled is that some chapters are particularly parochial, restricting themselves entirely to the USA (or perhaps extending to North America). This is particularly the case for the assessment of the impact of crop production on climate. Other chapters cast the net a little wider but the major emphasis remains on the crops and growing conditions of the heavily industrialized agricultural regions. In part this simply re¯ects where most of the work on climate change impacts has been done, but it is essential with the demographic and food requirement trends forecast over the next few decades that we extend our consideration to the largely tropical `developing country' regions. Some of the contributors certainly communicate strongly their sense of urgency about the problem of future food security and sustainability, and the additional concerns that climate change overlays. Faced with global warming, the agricultural challenge is not really the problems of the extension of temperate farming poleward or upward, but preventing reductions in yield caused by drought and high temperature stresses in the tropics and sub-tropics, and developing sustainable systems. In addition to the facts and understanding reviewed, the book is thought provoking because of the contrast in
attitudes between contributors. For example, inclusion of the chapter on the impact of agriculture on climate triggered for me the argument about whether intensi®cation of crop production on existing areas is less environmentally damaging than increasing production by expanding areas. Another contrast was the importance dierent reviewers placed on the role of photosynthetic acclimation to long term growth in high CO2 concentrations: in several crops it seems that little `down-regulation' takes place, when examined carefully and realistically. Several chapters also contrast in their attitude to the merits of simulation models for prediction of impacts. In particular, one aspect of the argument was whether point-scale detailed physiological models can be used sensibly in larger `regional scenario' assessments. Some chapters point out that because of the lack of experimental crop yield data with realistic, interacting factors such as high temperature, CO2 and water shortage, we are faced entirely with guesstimates from models and, in the words of Young and Long, these model estimates for many crops are rather like `betting on a horse race, with all its uncertainties and potential surprises, with the added handicap of only having seen the horse move in its box and never on the racecourse'. I can only hope this pithy expression might cause a little hesitation before funding agencies invite yet more modelling `desk studies' without being willing to fund the necessary experimental work and analysis. I read this book shortly after attending the International Crop Science Congress in Hamburg in August 2000. A depressing refrain from speakers and attendees alike at that congress was that despite the obvious impending food supply crisis there was a woeful lack of interest in crop science, both from funding agencies and governments and from prospective scientists. The reasons oered were the simplistic logic applied by governments (at least in the highly industrialized countries) that the continuing world surpluses of basic crop products and the consequent fall in world prices have removed the incentive for research. This has resulted in the collapse in many countries of demand for education in crop science in particular, and agriculture in general. If anything should change opinions about the need for crop physiology and encourage new scientists to get involved, it is the set of problems and questions these chapters articulate. This book also forms an impressive showcase for the extensive understanding that has developed from the many years of work on crop responses to the environment. Outsiders, including many other scientists, often regard the `climate change impact' work as recent `band wagon' research, without realizing that the major part of it is based on a solid grounding of decades of experimental crop physiology, initially unrelated to climate change. Similarly, critics and sceptics do not realize that the task of synthesizing crop physiology understanding and focusing it on the relatively new problem of anthropogenic climate change over the last two decades has provided us with much useful information for improving crop growth in the range of present climates and conditions around the world. As the delegates to the International Crop Science Congress declared (see the `Hamburg Declaration' http:// www.cch.de/CROPSCIENCE/hamburg_declaration.html)
Book Reviews we simply have to do this in order to prevent massive food shortages over the coming decades, with or without climate change. James I. L. Morison # 2001 Annals of Botany Company
doi:10.1006/anbo.2000.1303 Sherwood BR, Gardiner BG, Harris T, eds. 2000. British saltmarshes. 417 pp. Cardigan, UK: Forrest Text for the Linnaean Society of London. £45 plus p&p (hardback). (Available from: Forrest Text, Swn y Nant, Tresaith, Cardigan, Ceredigion SA43 2JG, UK. E-mail [email protected]) The title of this book may suggest a general account of saltmarsh vegetation and ecology, but this is in fact a collection of papers covering a wide range of saltmarshrelated topics, some of a general nature and some more speci®c. From the reader's point of view this may have advantages and disadvantages. Although the overview one might require is not necessarily available some topics can be covered in much greater depth than would be possible in a general text on the subject. In this case, the latter advantage more than compensates for the lack of a general summary. The introductory chapter is concerned with the `functional role of saltmarshes in linking land and sea'. The use of the word `function' in ecology is often rather worrying because it suggests some sense of purpose. The `function' may be linked to human needs, in which case the focus may be on the mechanical eect of saltmarshes in buering the shoreline, protecting it from the erosive power of waves. Since saltmarshes develop only on low-energy shores, however, such an eect can only operate in extremely unusual conditions. Alternatively, `function' may refer to the way in which saltmarshes work, as when they accumulate organic sediments and then release these to other ecosystems, and this is the emphasis here. The saltmarsh is productive, over a kilogram of dry matter being produced per square metre each year, and the litter produced has a half life of only 3±10 months, microfauna being responsible for much of its loss. Allochthonous particulate matter is also added by the sea, leading to overall accretion rates of up to 4 mm per year in Essex. Some organic matter, however, both ¯oating, particulate suspended, and dissolved is removed by the sea and provides an energy base for other marine ecosystems. Such is the `functional signi®cance' of the saltmarsh, and its `functional age' relates to its tendency to import (when young) or export (when mature) organic material. Besides exporting organic materials, saltmarshes may absorb certain elements, including those responsible for eutrophication. A chapter on nutrient processing examines this possibility and comes to the conclusion that up to half of the nitrate load in an estuary can be absorbed onto the sediments of the saltmarshes. Phosphates, however, behave dierently; the marsh may be a source of P in summer due to oxidation and a sink in winter when conditions become more anoxic.
135
Saltmarshes have been used as a model system for studies of successional processes since the concept of succession was ®rst put forward. One such example is provided in this collection, namely the 85-year-old saltmarsh at Berrow in Somerset, described by A. J. Willis. The complexity of succession is well illustrated here because of the interaction of developing dune systems with the saltmarsh, leading to the formation of brackish reed beds and ultimately perhaps to enclosed dune slacks. Another study at Morecambe Bay illustrates the long-term eects of sheep grazing with such sensitive species as Limonium vulgare and Atriplex portulacoides being eliminated in favour of grazing resistant grasses. Salt marshes have also been frequently used in studies of competition between plant species, possibly because of their relatively simple composition and structure and their general spatial uniformity with only gradual gradients. In a study of the saltmarsh community at Stikey in Norfolk, Davy and colleagues demonstrate the importance of competition, as illustrated by the interaction between Salicornia europaea and Sueda maritima. The former is suppressed by the local presence of the latter, but its earlier seed germination allows it to survive in an uneasy coexistence. No book on saltmarshes would be complete without a chapter on Spartina. The story of Spartina anglica in Poole Harbour is brought up-to-date by Raybould, who describes its decline over the past 50 years. Once considered a serious pest it is now retreating again. Heavy infections of ergot are currently being recorded in its population, indicating perhaps the evolutionary and ecological response of pathogens to a newly arrived species. The decline of Spartina has brought bene®ts both in the deepening of channels and in the response of wading birds, whose populations are now increasing as Spartina declines. Animal life in saltmarshes is very well represented in this collection of papers, balancing the tendency for plants to dominate most texts concerning this habitat. Molluscs, ostracods, insects (including several chapters on beetles and one on Lepidoptera), mites and amphibians are covered. The last named, of course, concentrates on the natterjack toad which, unlike many saltmarsh plant species, seems to thrive under heavy grazing regimes which lead to short turf and ephemeral pools. As in the management of so many habitats, con¯icts of conservation interest are bound to arise in saltmarshes. Grazing is generally considered to be a negative factor in the maintenance of high plant species diversity on saltmarshes, but many of the natural grazers, such as barnacle and pink-footed geese, are themselves of high conservation value. Using sheep to graze the upper marsh leads to grass domination, particularly sea couch (Elytrigia atherica) and this is the preferred habitat for breeding among redshank. As is so often the case, the choices in conservation are not simple ones. The assemblage of papers contained in this book is, without exception, informative and stimulating. Most papers have a strongly review character, and provide a succinct and up-to-date statement on their chosen topic, but many also provide new data and information in a brief, uncluttered form that adds substantially to the current state of knowledge. As its title implies, the studies are all
133
book, probably because they have not yet been developed as clearly-established research topics in Mediterranean countries. In general terms the research reviews contained in this book are well-structured and clearly written. My main question before reading the book was whether or not it provided a comprehensive overview of the research on these important tree species. After reading it, my short answer to this question is `yes'. Of course, the book relies on the topics presented at the workshop, but it covers most of the subjects related to Mediterranean pine ecology and, to a lesser extent, management. Its contents are, on the whole, clearly and logically presented, and the various authors make good attempts to summarize issues. For this reason, it might be of great use to researchers directly involved in the study of Mediterranean forests. There are some weaknesses, or topics that should be developed further, such as the intraspeci®c variability found in the dierent processes and subjects considered in the book; there are also some themes that have not been included at all, probably because there is not enough information about them. Nevertheless, the publication of a book such as this is the best way to identify the areas in which there is a large amount of information, as opposed to those about which little is known. From my point of view, this attempt to integrate past and present information from very dierent research groups makes a valuable addition to the research literature on this subject. Javier Retana # 2001 Annals of Botany Company
doi:10.1006/anbo.2000.1306 Reddy KR, Hodges HF, eds. 1999. Climate change and global crop productivity. 472 pp. CAB International: Wallingford & New York. £75 (hardback). If, like me, you have a bookshelf groaning with tomes about climate change impacts, and an in-tray full of publishers' ¯iers for this academic year's new crop, then you will probably hesitate to buy yet another. However, if you are an agriculturalist or crop scientist and make only one purchase this year in this subject area, then this should certainly be your choice. The book is an authoritative and comprehensive review of all aspects of the eects of anthropogenic climate change on crop growth, with 21 chapters provided by some 50 hugely experienced contributors. After setting the scene of what atmospheric and climate changes are likely, and what evidence there is for climate change, the ®rst section goes on to include a useful assessment of agricultural contribution to climate change, something that is often overlooked by crop scientists preoccupied with increasing productivity. The nextÐand longestÐsection then covers, in separate chapters, the major grain crops (wheat, rice, maize and sorghum), a major legume crop (soybean), tuber and root crops, vegetable crops, grassland and rangeland, timber and even CAM metabolism crops. This section then discusses cropweed interactions, pests and soil organic matter
134
Book Reviews
changes, and includes an additional chapter on the interactions of various environmental changes including UV-B and ozone. The last two sections deal with mitigation strategies such as breeding and biotechnology, and the economic and social impacts of change on global, regional and local food production and trade. There is little that can be faulted in the individual chapters, which are generally concise and usefully critical assessments of the current understanding. Many emphasize recent work, which is valuable in a fast-expanding subject. It might be felt that the subject of high CO2 , and plant growth in particular, is over-reviewed and hardly merits another volume. However, the bene®ts of this book are the comprehensive subject coverage and that the authors have been well-instructed by the editors to review climate change widely, and to consider in particular temperature and water status eects in addition to the `CO2 eect' on their particular subject material. Each chapter also concludes with a consideration of how changes might be mitigated, for example by crop breeding, or by agronomy and management. Many of the speci®c crop chapters are excellent examples of the fundamental integration of genetic, cellular, whole plant and environmental science that is the distinguishing feature of crop science. The other chapters give an essential context to the crop science details, and remind the reader of the environmental and economic aspects. The book will therefore be useful to all specialist climate change or agricultural researchers, and will be a valuable reference text for post graduate courses in these areas. A minor problem is that there is some variation in how up-to-date the chapters are ( for example the important ®nal chapter on food production and trade uses population projections from 1994, which have been signi®cantly revised since), but in general the editing has achieved a wellintegrated common format and style, and the production quality is excellent. A criticism that should be levelled is that some chapters are particularly parochial, restricting themselves entirely to the USA (or perhaps extending to North America). This is particularly the case for the assessment of the impact of crop production on climate. Other chapters cast the net a little wider but the major emphasis remains on the crops and growing conditions of the heavily industrialized agricultural regions. In part this simply re¯ects where most of the work on climate change impacts has been done, but it is essential with the demographic and food requirement trends forecast over the next few decades that we extend our consideration to the largely tropical `developing country' regions. Some of the contributors certainly communicate strongly their sense of urgency about the problem of future food security and sustainability, and the additional concerns that climate change overlays. Faced with global warming, the agricultural challenge is not really the problems of the extension of temperate farming poleward or upward, but preventing reductions in yield caused by drought and high temperature stresses in the tropics and sub-tropics, and developing sustainable systems. In addition to the facts and understanding reviewed, the book is thought provoking because of the contrast in
attitudes between contributors. For example, inclusion of the chapter on the impact of agriculture on climate triggered for me the argument about whether intensi®cation of crop production on existing areas is less environmentally damaging than increasing production by expanding areas. Another contrast was the importance dierent reviewers placed on the role of photosynthetic acclimation to long term growth in high CO2 concentrations: in several crops it seems that little `down-regulation' takes place, when examined carefully and realistically. Several chapters also contrast in their attitude to the merits of simulation models for prediction of impacts. In particular, one aspect of the argument was whether point-scale detailed physiological models can be used sensibly in larger `regional scenario' assessments. Some chapters point out that because of the lack of experimental crop yield data with realistic, interacting factors such as high temperature, CO2 and water shortage, we are faced entirely with guesstimates from models and, in the words of Young and Long, these model estimates for many crops are rather like `betting on a horse race, with all its uncertainties and potential surprises, with the added handicap of only having seen the horse move in its box and never on the racecourse'. I can only hope this pithy expression might cause a little hesitation before funding agencies invite yet more modelling `desk studies' without being willing to fund the necessary experimental work and analysis. I read this book shortly after attending the International Crop Science Congress in Hamburg in August 2000. A depressing refrain from speakers and attendees alike at that congress was that despite the obvious impending food supply crisis there was a woeful lack of interest in crop science, both from funding agencies and governments and from prospective scientists. The reasons oered were the simplistic logic applied by governments (at least in the highly industrialized countries) that the continuing world surpluses of basic crop products and the consequent fall in world prices have removed the incentive for research. This has resulted in the collapse in many countries of demand for education in crop science in particular, and agriculture in general. If anything should change opinions about the need for crop physiology and encourage new scientists to get involved, it is the set of problems and questions these chapters articulate. This book also forms an impressive showcase for the extensive understanding that has developed from the many years of work on crop responses to the environment. Outsiders, including many other scientists, often regard the `climate change impact' work as recent `band wagon' research, without realizing that the major part of it is based on a solid grounding of decades of experimental crop physiology, initially unrelated to climate change. Similarly, critics and sceptics do not realize that the task of synthesizing crop physiology understanding and focusing it on the relatively new problem of anthropogenic climate change over the last two decades has provided us with much useful information for improving crop growth in the range of present climates and conditions around the world. As the delegates to the International Crop Science Congress declared (see the `Hamburg Declaration' http:// www.cch.de/CROPSCIENCE/hamburg_declaration.html)
Book Reviews we simply have to do this in order to prevent massive food shortages over the coming decades, with or without climate change. James I. L. Morison # 2001 Annals of Botany Company
doi:10.1006/anbo.2000.1303 Sherwood BR, Gardiner BG, Harris T, eds. 2000. British saltmarshes. 417 pp. Cardigan, UK: Forrest Text for the Linnaean Society of London. £45 plus p&p (hardback). (Available from: Forrest Text, Swn y Nant, Tresaith, Cardigan, Ceredigion SA43 2JG, UK. E-mail [email protected]) The title of this book may suggest a general account of saltmarsh vegetation and ecology, but this is in fact a collection of papers covering a wide range of saltmarshrelated topics, some of a general nature and some more speci®c. From the reader's point of view this may have advantages and disadvantages. Although the overview one might require is not necessarily available some topics can be covered in much greater depth than would be possible in a general text on the subject. In this case, the latter advantage more than compensates for the lack of a general summary. The introductory chapter is concerned with the `functional role of saltmarshes in linking land and sea'. The use of the word `function' in ecology is often rather worrying because it suggests some sense of purpose. The `function' may be linked to human needs, in which case the focus may be on the mechanical eect of saltmarshes in buering the shoreline, protecting it from the erosive power of waves. Since saltmarshes develop only on low-energy shores, however, such an eect can only operate in extremely unusual conditions. Alternatively, `function' may refer to the way in which saltmarshes work, as when they accumulate organic sediments and then release these to other ecosystems, and this is the emphasis here. The saltmarsh is productive, over a kilogram of dry matter being produced per square metre each year, and the litter produced has a half life of only 3±10 months, microfauna being responsible for much of its loss. Allochthonous particulate matter is also added by the sea, leading to overall accretion rates of up to 4 mm per year in Essex. Some organic matter, however, both ¯oating, particulate suspended, and dissolved is removed by the sea and provides an energy base for other marine ecosystems. Such is the `functional signi®cance' of the saltmarsh, and its `functional age' relates to its tendency to import (when young) or export (when mature) organic material. Besides exporting organic materials, saltmarshes may absorb certain elements, including those responsible for eutrophication. A chapter on nutrient processing examines this possibility and comes to the conclusion that up to half of the nitrate load in an estuary can be absorbed onto the sediments of the saltmarshes. Phosphates, however, behave dierently; the marsh may be a source of P in summer due to oxidation and a sink in winter when conditions become more anoxic.
135
Saltmarshes have been used as a model system for studies of successional processes since the concept of succession was ®rst put forward. One such example is provided in this collection, namely the 85-year-old saltmarsh at Berrow in Somerset, described by A. J. Willis. The complexity of succession is well illustrated here because of the interaction of developing dune systems with the saltmarsh, leading to the formation of brackish reed beds and ultimately perhaps to enclosed dune slacks. Another study at Morecambe Bay illustrates the long-term eects of sheep grazing with such sensitive species as Limonium vulgare and Atriplex portulacoides being eliminated in favour of grazing resistant grasses. Salt marshes have also been frequently used in studies of competition between plant species, possibly because of their relatively simple composition and structure and their general spatial uniformity with only gradual gradients. In a study of the saltmarsh community at Stikey in Norfolk, Davy and colleagues demonstrate the importance of competition, as illustrated by the interaction between Salicornia europaea and Sueda maritima. The former is suppressed by the local presence of the latter, but its earlier seed germination allows it to survive in an uneasy coexistence. No book on saltmarshes would be complete without a chapter on Spartina. The story of Spartina anglica in Poole Harbour is brought up-to-date by Raybould, who describes its decline over the past 50 years. Once considered a serious pest it is now retreating again. Heavy infections of ergot are currently being recorded in its population, indicating perhaps the evolutionary and ecological response of pathogens to a newly arrived species. The decline of Spartina has brought bene®ts both in the deepening of channels and in the response of wading birds, whose populations are now increasing as Spartina declines. Animal life in saltmarshes is very well represented in this collection of papers, balancing the tendency for plants to dominate most texts concerning this habitat. Molluscs, ostracods, insects (including several chapters on beetles and one on Lepidoptera), mites and amphibians are covered. The last named, of course, concentrates on the natterjack toad which, unlike many saltmarsh plant species, seems to thrive under heavy grazing regimes which lead to short turf and ephemeral pools. As in the management of so many habitats, con¯icts of conservation interest are bound to arise in saltmarshes. Grazing is generally considered to be a negative factor in the maintenance of high plant species diversity on saltmarshes, but many of the natural grazers, such as barnacle and pink-footed geese, are themselves of high conservation value. Using sheep to graze the upper marsh leads to grass domination, particularly sea couch (Elytrigia atherica) and this is the preferred habitat for breeding among redshank. As is so often the case, the choices in conservation are not simple ones. The assemblage of papers contained in this book is, without exception, informative and stimulating. Most papers have a strongly review character, and provide a succinct and up-to-date statement on their chosen topic, but many also provide new data and information in a brief, uncluttered form that adds substantially to the current state of knowledge. As its title implies, the studies are all