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large spatial and temporal scales that are appropriate for, e.g., birds or mammals. However, there is also the other possibility: that the metapopulation perspective could be broadened and its assumptions (e.g. the discreteness and the two-level character of the dynamics) could be relaxed without dismissing the conceptual and mathematical foundations of the dynamics. 1 believe that if it could be possible, then metapopulation biology would become the general and universal theory of all of ecology. REFERENCES HANSKI I.A. & GILPIN M.E. (1997): Metapopulation biology: Ecology, genetics, and evolution. Academic Press, London. David Storeh

OTHER BOOKREVIEWS U. Starfinger, K. Edwards, 1. Kowarik & M. Williamson: PLANT INVASIONS: E C O L O G I C A L MECHANISMS AND HUMAN RESPONSES; Backhuys Publishers, Leiden, 1998, 362pp. Price USD 97.-,

ISBN 90-5782-005-6 G. Brundu, J. Brock, I. Camarda, L. Child & M. Wade (eds.): PLANT INVASIONS: SPECIES E C O L O G Y AND ECOSYSTEM MANAGEMENT; Backhuys Publishers, Leiden, 2001, 338pp. Price USD

220.-, ISBN 90-5782-080-3 Plant invasions are still at the centre of attention for biologists as they have a great impact on many areas of human activities such as agronomy, forestry, landscape management and, consequently, economy and legislation. While the appearance of new species is connected mostly with the movement of people and goods movement, the main driving forces enabling the plant to reside and spread are mostly linked together with changes in land use and with the area disturbations. Once established, the introduced plant can proceed into natural, undisturbed plant communities as well. Since activities promoting the new plant appearance and spreading are still increasing in our world, they bring more new cases to study. It is well known that most alien plant species have little effect and only some have noxious effects on biodiversity and biotopes. Thus it makes sense to discuss what the invasive success is, and how to measure and how to predict the invasive impact and success. It is also important to reflect how to perceive the newcomers which have nearly no harmful influence. The next researeh on the yet-residing and spreading species concentrates on several main approaches, which are, together with the general questions, the theme presented in the reviewed books. (1) The inventory of new plants resulting from new species records in new areas, generating long lists of species and numerous statistics about their fitting to plant families, functional groups and different habitats. (2) Detailed descriptions of new cases. (3) Invasive species population biology studies, sometimes comparing the new species to the closely related natives. (4) The search for the specific characters of invasive species in general and/or in the studied area. (5) Trying to solve the management to prevent the harm and/or to eradicate widespread invaders. It is a bit of a pity that invasive species draw little attention to the studies of the genetic structure of populations, to the studies at the metapopulation level and that only a few predictive models exist. The studies presented come from North America and Europe. Similarly as in the previous proceedings (BROCK et al. 1997), only one study compares invasive floodplain plants in Europe to those in Japan in the first book and one is from Argentina, one from Mexico and one from Malaysia in the second. The first book (1998, Plant invasions: Ecological mechanisms and human responses) builds on workshop materials presented at the 4th International Conference on Ecology of Invasive Alien Plants, held in October 1997 in Berlin and organized by the Botanical Society of Berlin and Branderburg and the Institute of Ecology and Biology of the Technical University Berlin. The book starts with two general parts (1) General aspects, (2) Perception and legislation, which are followed by the next three (3) Case studies I: Species, (4) Case studies II: Biotopes/regions, (5) Plant-insect interactions. Altogether there are 31 studies..

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In addition to the points mentioned above, the first book focuses on questions regarding the perception of invasive effects. Three papers deserve to be mentioned. The paper by Mark Williamson that postulates the ten-rule for invasive plants (10% of imported plants become casual, of them 10% become established, of them 10% become pests) and discusses how and from which point of view to measure the invasive impact. The Edward's critique of the general approach to invasive plant species points out how narrow the range of facts about a problem usually leads to the conclusions about the threat of extinction of a native species and/or change in the ecosystem. Uta Eser pinpoints that even if science can finally bring facts about what is, what should or ought to be done, social aspects should be included and field biologists should contribute to political decisions. Scientists should be aware of the historic and social contexts in which they speak and act. It means that they should carefully choose their language. Conservationists tend to idealize pristine nature as intrinsically good, harmonic and stable and their terms invasion, green invader, alien plant, threat to biodiversity bring emotionality. The new aspects provided in the second book (2001, Plant Invasions: Species Ecology and Ecosystem Management) include the discussion of the spread of native species into new plant communities and habitats and the spread of species both native and invasive into adjacent areas. The book stems from the 5th Intemational Conference on the Ecology of Invasive Alien Plants held in October 1999 on the Mediterranean island of La Madalena, Sardinia, Italy. Quantifying and understanding ecological issues relating to plant invasions were set as the conference goal. The book starts with a helpful index of main alien plant taxa presented in the book and their common and family names, brief descriptions, and references to pages in the text. The next introductory part (General aspects) is followed by four special parts: (1) Species, (2) Invasive plants in protected areas, (3) Habitats, biotopes, regions, (4) Invasive plant management. Altogether 34 papers are presented: two on a general basis, 18 case studies, 5 management studies and 8 studies related to special areas (protected, urban, riparian, mountain). An attempt to include the most interesting information presented at the conference, however, has led to the choice of a very economical way of presenting the information in very compact texts, tables and figures, which are sometimes difficult to read, and to fuzzy photos. Both books are significant sources of information for people dealing with conservation biology and legislation, as well as for everybody who is interested in flora and vegetation changes. The books bring many pieces of knowledge about new invasive plants, their management and invoke thinking about the perception of invasions. REFERENCES BROCKJ.H., WADE M., PY~EKP. & GREED. (1997): Plant invasions: Studiesfrom North America andEurope. Backhuys Publishers, Leiden. V~ra Hadineov~i S.P. Hubbell: THE UNIFIED NEUTRAL THEORY OF BIODIVERSITY AND BIOGEOGRAPHY;

Monographs in Population Biology 32, Princeton University Press, Princeton and Oxford, 2001, 375 pp., 126 Figs. Price USD 35.-, 1SBN 0-691-02128-7 Whether you like it or not, biodiversity is firmly established as the modem symbol for everything alive, natural and desirable. In the heat of the debate around the intrinsic and instrumental values of biological diversity one sometimes longs for the simple theories of the 1960s and 1970s. Almost 35 years after MacArthur and Wilson published their Island Biogeography Stephen P. Hubbell of the University of Georgia takes up this strand and unites it with principles that have long proved indispensable in evolutionary biology and population genetics. The title may sound pretentious, but the author calmly addresses one fundamental problem of community ecology after the other and demonstrates, using simple simulation models, that they can be reduced to a small set of assumptions: He finds stringent explanations for Preston's canonical distribution of abundance and rarity and for the fact that species-area relationships follow a power law and that if one looks closely this slightly changes its parameters across scales. Who would not be impressed with a theory providing so many solutions that have so long been overdue? HubbeU's assumptions are provocative: Individuals of all species are fully equivalent in his model (he defines communities as consisting of trophically equivalent organisms like trees), obeying the same rules based on speciation, extinction and dispersal. Due to the linear relation between area and metaeommunity size,

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sampling effects carry through right to the biogeographic level. There is no competition and changes in composition are stochastic. His model systems generate complex and globally stable patterns that correspond closely to empirical data from tropical tree communities. One key for the generation and conservation of richness is drift: Just as the well-known genetic effect shifts allele frequencies in the absence of selection, ecological drift continually creates variable local species compositions even in the most homogeneous world. An important condition for this is limited dispersal. Thus, while the individual community undergoes great stochastic changes due to immigration and extinction, it remains embedded in a much more inert metacommunity, a large reservoir from which species are continually brought forward. At this point Hubbell strikingly converges with the species pool or quasi-neutral hypothesis recently developed by European vegetation scientists. This hypothesis explains local composition as much by the nature of its surroundings as by local processes. It is time that this transatlantic parallelism converges. Just as the species pool hypothesis did, Hubbell confronts our thinking that customarily sees adaptation and competition everywhere, with the possibility of community assembly by largely stochastic dispersal and demonstrates that this offers a better explanation of some fundamental features of the real world. The closing chapter proves that his purpose is far from iconoclasm and mere provocation. Hubbell has no doubt that adaptation and competition, and, as a consequence, environmentally driven compositional gradients really exist. However, his theory tells us that we have so far applied the wrong null hypotheses to the study of natural patterns: Diversity may be generated in the absence of heterogeneity and be perpetuated in the presence of competition. This calls for more sophisticated proof of conventional wisdom than we are used to attempting. Behind all this Hubbell suspects evolutionary tradeoffs between the eompetetive and dispersal ability of species that would only rarely be disrupted as in the case of aggressive invaders. The unified theory predicts that current competitive exclusion should be indicated by deviations from the canonical frequency-abundance curves. The author opens up a wealth of new and testable questions that come with a toolbox to attack them. This should be great inspiration to all community ecologists who have been wrestling with the scaling of species richness, species pools and spatial hierarchies! J6rg E w a l d T.J. Case: AN ILLUSTRATED GUIDE TO THEORETICAL ECOLOGY; Oxford University Press, New

York, Oxford, 2000, 449pp. Price USD 54. 95, ISBN 0-19-508512-4 There are two kinds of textbooks on mathematical biology for those who like to have everything in the categories. One of them are textbooks dealing with problems and their solutions in mathematics including different definitions of the same terms and their characteristics for better understanding and use. These are typical books for mathematicians but not for biologists for whom it is a problem to understand a formal text and who do not understand the sense of abstract constructions. On the other hand there are textbooks of biological problems, which can be or could have been solved through mathematical means. These are typical books for biologists who understand the formalism used in biology but not for mathematicians who do not like anything outside of their world of statements that are either true or not true. Case's book could be considered a book halfway between these two extremes. It is neither a book of mathematical problems in biological models nor a book of mathematical modelling in biology. It seems to be a textbook for biologists-engineers who want to solve some of the simple/standard problems in population or community ecology. This concept brings together all the weaknesses and strengths of both of the types of books mentioned above. In general, although it could seem that there are too many formulae without interpretations from the biological point of view, there are many frames giving explanation of computation of the specific problems placed in the text. And although the book may seem mathematically too simplified to be used as a correct mathematical textbook, the main methods and models commonly used in mathematical biology have been elaborated very well. In my opinion, the best way to understand the text is to read it twice: first as a biologist and then as a mathematician. The book is divided into two parts - "Population Ecology" and "Interaction and Community Ecology". This division respects the biological view of the given problems and thus, mathematical concepts are found in several places in the book. Fortunately for the reader there are many links connecting the individual chapters to definitions and mathematically similar themes that have appeared earlier in the text. Unfortunately for the reader, throughout the text, the author uses some symbols, either standard biological symbols such as K or standard mathematical symbols such as 2, which are specified only when they are used for the first time.

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The part entitled Population Ecology begins with as universal a formula as possible. This formula is regarded by all physicists as a base law of physics and it is called the universal law of conservation. The number of individuals is considered the entity of conservation in the text and the law says: "The difference in the number of individuals between the time points t and t+dt in any closed space equals the number of individuals that were born minus the number of individuals that died in the same space between the time points t and t+dt plus the number of those that immigrated minus the number of those that emigrated from the same space between the time points t and t+dt." Some models mainly the models of exponential and logistic growth are derived from this law and the book explains some methods of how to plot, solve and interpret these models. In the following chapters, these models are expanded by a spatial structure (the classical wave/diffusion equation and the random walk model) and by the age or stage structure (matrix models). The reader is introduced to the form of solving the diffusion equation and estimating the value of the diffusion parameter D. Although the author's intention is not to persuade the reader about a correspondence between the reality and the models, there are two case studies. Unfortunately these examples do not verify the models. The question is why the mentioned solution of the wave equation for 2D space contains NO, which cannot be interpreted as a number of individuals spreading over the space. The links between Malthus's coefficient (born minus dead) and the eigenvalue (~.) are very well explained here so that the textbook could help biologists to understand some more sophisticated texts in theoretical biology. However, the method of counting left and right eigenvectors that is necessary for the dominant eigenvalue sensitivity analyses is missing. For those biologists who do not believe in Math-Bio, it could be a problem to do some unrealistic exercises as, for example, determining what the population size will be on a small island if in 1995 the population was one hundred individuals and this population has a geometric growth. In my opinion, those biologists who commonly use the demographic characteristics of a population should see the chapter in which you can find out about the correspondence between models and demographic characteristics. The most frequently used models in this chapter are the matrix models and the Lotka-Euter model. Here the reader can learn for example how to recognize a stable age structure if the dominant eigenvalue is known. The following two chapters are an introduction to the optimization and stability theories. They are entitled "Density Dependent Population Growth" and "Population Regulation, Limiting Factors, and Temporal Variability". An introduction to the chaos theory is placed here along with the logistic growth models. I was pleasantly surprised when I read this chapter because the part about chaos follows after the relevant description with a method of recognition whether a certain time series belongs to the chaotic region (which means that the modelling step is so great that there is not any similarity between continuous and discrete models). The concepts of stability and local are also explained in this and the following chapters. I am afraid that if I were only a biologist I would think, according to the text, that there is not much difference between the discrete and continuous models and between stability and mechanisms that lead to the stability. And this is the headache of the whole text. It is because to explain terms such as continuous, stability and local stability around point seems to be very difficult, and biologists find it difficult to appreciate their importance. Moreover the term stability is explained here on a discrete situation and the term around the point on an example of Taylor's expansion. The final chapters of the first part of Case's book introduce life history, trade-off and evolutionary models. Since the game theory originated in the US, I wonder why the chapter about evolutionary models is not based on it. But it could be that the author wanted to show the efficiency of analytical models or did not like to add additional mathematical area for the sake of a better coherence of the book. As I have mentioned, the next section is entitled "Interaction and Community Ecology". It consists of three coherent parts. The first of them contains two chapters and deals with exploiting resources such as grazing and predation mechanisms. I was delighted to read this chapter because I have always missed a similar text. A lot has been written about predation but none of it strictly focused on modelling applicable mechanisms. Here the reader can find out about for example the dependence of prey captured over a period of time on prey density, but these chapters seem to be the basis for the "two preys-one predator" models. Unfortunately, there is not much relation between this model and the first two chapters of the other part just as there is little mutual relation between chapters in general. In the next part, the reader can find predator-prey and competition models with some examples of real data and very nice and comprehensible two- and three-dimensional graphs. These graphs illustrate the main terms

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such as equilibrium and mechanisms leading to stability. However, the reader has to bear in mind that this is only an illustration and not proof and it cannot be extrapolated by any speculation. Another problem of the graphical way to understanding the problem is that it does not help us to comprehend multispecies communities. A method for how to prove the stability of an equilibrium is also provided. The method that is explained here is usually called the linearization method and although it is applicable even to cases of more species than two and there are several methods of linearizing the model, the author uses only Taylor's expansion in the predator-prey model. He may not want to complicate the problem, but there are more ways how to linearize a model that are more easily applicable to some other models but they have certain conditions that must be verified. This method proves only the stability around one point, but the space in which any state is attracted to the equilibrium can be infinitely small. If Ljapunovov's method were used, this problem would not arise at all. And this is an example in which Ljapunovov's method solution is well known. On the other hand, it is true that to solve the other models by Ljapunovov's method is very difficult and in all the biological papers I have seen the linearization method is used. Associating predation and parasitism, which are mathematically identical interactions could be a problem for biologists. The absence of rules from numerical mathematics and initialization systems (systems to find model coefficients and verify if the used model is correct) can be a problem for those biologists who want to use a computer for solving problems. The last part is dedicated to the most recent developments in theoretical ecology. It is called metapopulation modelling. This part is a little different from classical mathematical ecology because the basic idea is built on the probability model. There are not supposed to be any interactions among individuals. There is an assumption about the probability of emigration for each individual and the probability of finding each patch by a certain individuals. In spite of it, the model is described by means of equations that are very similar to the equations describing the previous themes. [nstead of the number of individuals, the ratio of occupied patches is applied. Additionally, the book contains a very nice appendix that explains not only the mathematical minimum for understanding the text, but also the "Terms and Methods of Model Building in Population Biology". Ted J. Case is a Professor of Biology at the University of California, San Diego. He has written a very nice textbook on Theoretical Ecology. Even though the graphical approach to mathematical understanding has a much stronger tradition in the USA than it has in Europe (thanks to the educational system) the book is a modern and easily comprehensible textbook that can introduce a biologist to themes that cannot be understood through classical mathematical texts.

Arno~t L. ~izling P.J. Benstead, P.V. Jos~, C.B. Joyce & P.M.Wade: EUROPEAN WET GRASSLANDS. GUIDELINES FOR M A N A G E M E N T AND RESTORATION; Royal Society for the Protection of Birds, Sandy, J999, 481 pp., 6 Maps. Price GBP 15.95, ISBN 1-901930-01-7 The volume brings an overview on the current state of wet grasslands in different parts of temperate Europe and suggests suitable management for maintaining their biodiversity. It consists of four sections that address various issues of wet grasslands, such as the biodiversity, site evaluation, management and restoration techniques. Several case studies describe variation of wet grasslands and their problems in different landscapes. In addition to the effective techniques recommended to grassland managers, the book also provides a suitable background for NGO projects focused on the conservation of rare wetland birds. Due to the latter the study is, probably, more a technical guide than a deeply rooted ecological comprehension of these dynamic and open ecosystems. In spite of the rather complicate design, the information presented in the text is clear; numerous figures and tables are also helpful. According to the title, readers of the book will seek to learn about the very concept of a "wet grassland". Obviously, the immense variability of the included ecosystems has steered the authors towards a rather broad concept. As a result, a manner of negative delimitation was applied to distinguish the wet grasslands from related ecosystems. To be clear, the specification which is on the list of appropriate plant communities according to the COR1NE classification can be useful only in the West European area where the above-mentioned system has been completed and adopted; in Central and East European countries a similar classification has not yet been accomplished and some of the units applied in the text thus remain rather obscure. To make it easier, the generalized concept of wet grasslands could be based on water fluctuation, which is the key factor in all of the

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biotopes concerned. For example, a reference to the seasonal or tidal water level regime in relation to ground surface, as described in terms of ecophase and ecoperiod sensu HE.rN'I"(1960), could be a useful tool in the fine delimitation of these ecosystems. The great value of these heterogeneous ecosystems, prevailingly situated in semi-natural and marginal lowlands, relies in their taxonomic biodiversity, which makes them hotspots of European landscapes. This is clearly documented by the inventory drafts given for plants, vertebrates (namely birds) and selected groups of invertebrates. The species lists are interesting, but a deeper ecological evaluation and meaningful interpretation of their identity from a biogeographical point of view is lacking. These important characteristics would be helpful namely in the assessment of conservational values and various threats. The recommendations regarding the maintenance of biodiversity provide an excellent guide for management practice. They combine wildlife conservation with sustainable agriculture in these highly productive environments. Respective principles regarding (1) grassland management, i.e., grazing (by different livestock and regime), mowing, topping and burning, (2) water management including water supply and distribution, water level control, and water quality, (3) management of associated biotopes, including drainage channels and scrubs/hedges, and (4) the wildlife management of plants, birds and invertebrates are dealt with separately. Particular objectives and techniques of monitoring and restoration are touched on as well. Because they combine the knowledge from low-cost laborious farming in less developed Eastern Europe with modem technologies and knowledge applied in the EU countries, these guidelines will be appreciated by both conservation agencies and agro-environmental programmes. Of special importance is Part 4 of the volume, which introduces case studies from 16 projects executed in Ireland (The Shannon Callows floodplain), the United Kingdom (tidal floodplain of Pulburough Brooks, The Broads Grazing Marshes), France (brackish marsh Marais de la Vacherie), the Netherlands (the polders of Eilandspolder and Polder Mijzen, floodplain De Veenkampen), Denmark (floodplain of River Brede), Sweden (Lake Homborga), Germany (floodplain of River Danube), Czech Republic (floodplain of Lu~nice River), Slovakia (floodplain of Morava River), Poland (floodplain of Biebrza River), Latvia (estuary of Vecdaugava), Estonia (Hullo and Sviby Bays in Wormsi Island, Matsalu Bay) and Belarus (floodplain of Mid Pripyat River). The volume under review demonstrates that the challenge of know-how exchange between countries of contrasting political and socio-economical constitutions has been successfully met.

Lenka Soukupov~ P.J. Jarvis: ECOLOGICAL PRINCIPLES AND ENVIRONMENTAL ISSUES; Pearson Education Ltd., Harlow, Essex, 2000, 303 pp. Price GBP 32.99, ISBN 0-582-36971-1

Though ecology lacks consistent theory, a fairly stabilized range of important issues and generalized concepts has already crystallized into an integrated set of principles regarding the complexity of living organisms and their non-living/physicalenvironment. In spite of the emphasis on the biological core in ecology, the blend of biological knowledge and physico-environmental materials is always a matter of an individual teacher's choice. In view of multiple time and space scales and the complexity of evolution-basedrelationships, many didactic approaches have been utilized in educational materials. Unless clarity and precision of background data are violated, most of these methodologies are justified, but only a few of them meet the demands of university education. The volume under review deserves proper acknowledgement, particularly with regard to its remarkable didactical treatment of basic present-day environmental issues. In nine chapters, the work elucidates fundamental concepts related to the most important events encountered in the current biomes of the Earth. Each of the chapters marked by striking titles posseses a logical structure consisting of a preliminary summary, exposure of key environmental issues, analysis of related ecological concepts, recommended environmental management, short conclusions and a list of "further reading". This text design and accompanying illustrations deserve a teacher's appreciation. The eight major topics described and richly documented in this textbook are as follows: (a) global interaction of land, air and water, (b) food, energy and nutrients, (c) ecosystem sustainability and chemical pollution, (d) species distribution and climatic change, (e) population growth and control, (f) biodiversity and species richness, (g) conservation and wildlife management, and (h) biological invasions, competition and the niche. Obviously, this selection comprises the essential problems usually covered by environmental sciences.

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The above-mentioned topics also suggest a sensitive choice oftransdisciplinary themes that can be found in theoretical biology, physical sciences and applied environmental fields. The book maintains a global view, refers both to temperate and tropical regions, and treats both wildlife and human-managed regions. This wide geographical and topical coverage results in a useful piece of educational material that will suit many universities teaching fully or partly in English. The uniform pattern and didactic methods are maintained throughout the individual chapters. First, the reader/student receives short information about the relevance of a particular topic; afterwards he/she gets an account of "key environmental issues" that are explained in a consistent text with a number of tables and illustrations (mostly in separate boxes); each subchapter is also accompanied by "questions and answers", discussion topics and recommended exercises. Apparently, the selection of striking examples of environmental events has resulted from the author's long teaching experience. Students will be attracted by such stories like "the snake that ate Guam" (p. 252). Many useful summaries of physical, chemical and behavioural interactions in plants and in the animal world will be welcome even by professionals in fields associated with ecology. The environmental key issues are further analysed in sections on the background of essential concepts which are, so far, available in the academic ecological resources. Called "Ecological Concepts", these subchapters offer a consistent overview of present-day ecological thinking and of the core ideas which could be called - in terms of the author - "ecological principles". The clear-cut text with numerous figures and tables interprets even the very complex biological processes, such as biogeochemical cycles, photosynthetic pathways, chemistry of chlorofiuorocarbons, population structure and growth, hereditary status of species and speciation, indices of diversity and equitability, habitat classification, etc. Reference to other ecological texts and unavoidable simplifications mark the prevailing educational methodology of the author. Other parts of the main chapters deal with environmental management. In these sections the reader will find various methods and guidelines to solve practical issues, such as the assessment of biodiversity (incl. Convention on Climate Change), the transfer and introduction of allied organisms (incl. Convention on International Trade of Endangered species - CITES), the introduction to genetic engineering and problems of genetically modified organisms, examples of integrated pest management, in situ and e x s i t u conservation, methods of restoration ecology, etc. Forestry and agriculture, the two frequent partners in environmental management are often quoted, lit is to be regretted that the remarkable results of the UNESCO's Man and Biosphere Programme have been omitted.] However besides the well-established concepts one finds in the text many new buzzwords, such as "hotspot" or "flagship species", which underline the quick development from environmental slang to scientific language. In environmental science, educational materials are rarely free from national limitations. The book under review spreads both global knowledge and universal wisdom, and thus can be adopted at different levels of education and may serve even as an informational basis for non-professionals that become involved in the conservation of natural ecosystems and settling with various landscape problems. Hopefully none of them will mind the small puzzle of three different imprints indicated on the title page and on the back of the title-page: Pearson Education, Prentice Hall or Pearson Education Limited ? Indeed, whoever is responsible for the production of this book deserves a compliment. Jan Jenik