Book Reviews

Ecology, 85(7), 2004, pp. 2053±2054 ᭧ 2004 by the Ecological Society of America

MEETING THE CHALLENGES OF MOVING ONTO LAND de Kroon, Hans, and Eric J. W. Visser, editors. 2003. Root ponents of an integrative examination of the status of our ecology. Ecological Studies. Volume 168. Springer-Verlag, understanding of root ecology. For example, Robinson, Hod- ge, and Fitter organized their review of constraints on root New York. xxi ϩ 394 p. $149.00, ISBN: 3-540-00185-9 (alk. paper). system form and function much like an architectural charette, ®rst considering the challenges of the soil environment, then discussing what aspects of root structure and physiology en- After decades of being characterized as ``the hidden half'' able roots to meet these challenges, and ®nally linking these of plant biology studies or relegated to a ``black box'' for primary characteristics to emergent properties of whole root community and ecosystem ecology research, interest in root systems. This design-centered approach and the authors' ef- ecology has moved from the margins of ecology to a central fective linkage of root function and evolutionary ecology position. Contemporary ecologists are demanding a better make this chapter an exciting introduction to the realm of understanding of how roots function, how roots respond to root ecology. their environment, and how roots in¯uence their environment. A. G. Bengough's consideration of root growth and func- This volume joins a handful of recent publications illumi- tion in relation to soil structure, composition, and strength is nating root lives and livelihoods in the soil habitat. Its focus similarly refreshing, in part because his focus on the soil is narrower than some, and its organization and themes re¯ect environment as habitat is unusual in the plant ecology lit- the ecological orientation of its contributors. A special erature. After introducing the soil environment and evaluating strength of this work is its evolutionary context: although the contributions and promise of imaging technology for bet- many root ecologists have spent untold hours separating roots ter understanding root-soil interactions, Bengough summa- from soil, the editors and their colleagues remind us that we rizes common effects of various soil physical conditions on have a lot to learn by exploring root interactions with the root elongation rate, and he promotes employing the concept complex abiotic and biotic components of soil. of least limiting water range (one of several developments in In designing their edited volume for the wide-ranging au- agronomy that this volume brings to the attention of ecolo- dience of Springer-Verlag's Ecological Studies series, de gists working in natural systems) as a tool to predict root Kroon and Visser have charged their participating authors to growth and functional responses to speci®c measurable soil provide an up-to-date evaluation of our understanding of the parameters. Such a tool might also provide a useful frame- mechanisms by which roots have adapted to the soil envi- work for ecosystem and global process modelers to link root ronment and the roles roots play in this habitat. This guiding growth response and root function to static and dynamic soil evolutionary perspective leads readers to consider the roles physical properties. of roots from their most ancient origin, and to approach the Smith, Smith, and Timonen's review of mycorrhizal rela- understanding of root function as a set of innovations based tionships and mycorrhizal ecology is remarkably accessible on some fundamental themes. About a third of the authors and thorough, introducing plant ecologists to the kinds and made explicit connections between root function or root roles distribution of mycorrhizal associations, the nature of re- and evolutionary processes. While the scope of this volume source exchange between plant and fungal symbionts, the ranges from biochemistry to ecosystem process, it is perva- range of plant responses to mycorrhizal symbiosis, and the sively root centric. Beginning with a thought-provoking over- synecology of mycorrhizas in both rhizosphere and plant view of root form and function, followed by chapters as- community contexts. The authors' rigorous and up-to-date sessing our understanding of root distribution in time and engagement of the latter two areas makes this chapter valuable space, and evaluations of key areas of root growth and func- for mycorrhizal researchers as well. Drawing upon their dis- tion considered at a whole plant level, the book addresses cussions of resource exchange and the mycorrhizal response how roots respond to the physical structure of soil, and then of the plant partner, they reveal how little we know about ventures into root interactions with soil biota, considering mycorrhizal roles in community structure, from potential im- competition with other roots, the complex array of interac- pacts on competitive interactions to the process of succession. tions with rhizosphere fungi and bacteria, and responses to Looking forward, the authors articulate a need for interdis- herbivory. By encouraging the authors to draw attention to ciplinary research and they emphasize the limitations of pur- speci®c challenges in root ecology research and to identify suing ecological research on naturally mycorrhizal plants in promising approaches and techniques, the editors serve the the absence of their mycorrhizal associations. needs of specialists in each ®eld as well as those of more Although these three chapters and several others satisfy the general ecology readers. reader with critically evaluative, synthetic, and forward-look- As a whole, this volume offers the reader a thorough ing reviews, some veer toward compendia and some are quite grounding in several key areas of root ecology, and it also narrow in scope. While most chapters succeed in introducing includes a few more narrowly focused reviews elaborating the non-specialist to speci®c aspects of root ecology, a few how roots cope with speci®c soil environments. Some chap- speak primarily to those already working in a particular sub- ters are magni®cent both as stand-alone pieces and as com- ®eld. Chapters on root exudates, root-animal interactions, and

2053 2054 BOOK REVIEWS Ecology, Vol. 85, No. 7 root physiological adaptation to ¯ooded environments were With a few exceptions, the volume lacks integration among particularly disappointing in these areas. chapters. Although this lack does not detract from the overall The authors did a great job of identifying useful approaches high quality of the individual chapters, it is a missed oppor- and methods, including emerging technologies and applica- tunity to explore, for example, the implications of root roles tions. It is especially encouraging to read about the devel- at the whole-plant scale for community and ecosystem prop- opment and utilization of tools to observe roots and the rhi- erties and processes. Greater integration may also have led zosphere with reduced disturbance. Results from in situ stud- to additional insights, including into the evolutionary dynam- ies were distributed throughout the volume, from the use of ics among plant roots, rhizosphere organisms, and the ter- a high-pressure ¯ow meter to measure hydraulic conductance restrial environment. Alternatively, the addition of a synthesis through root systems to the employment of microelectrodes chapter, considering the key themes and lingering questions to measure sub-millimeter scale variation in oxygen concen- raised by each author in the context of a broader evolutionary ecology perspective, might have served these ends and pro- tration in the rhizosphere. The promise of molecular and ge- vided the basis for a research agenda. netic tools is obvious, although their use is largely restricted Root ecology offers an opportunity to learn about the in- to studies involving microbes or to studies of root biochem- novations and developments occurring throughout this ®eld. istry or physiology. In contrast, new variations of more tra- In addition to enhancing our understanding of the diversity ditional isotopic and imaging tools are in use throughout the and complexity of the root habitat and root lives, approaching discipline. root ecology research with a good grasp of evolutionary his- If the literature cited in this volume is representative of tory may also help us to envision how root-soil interactions root ecology research in general, and I think this is likely, are likely to respond to changes in our environment. our understanding of root systems is biased strongly toward annual and herbaceous plants, especially toward common JULIE WHITBECK crop plants. It is clear that we ecologists have much to learn University of New Orleans from research published in the agricultural literature; it is Department of Biological Sciences likewise clear that we have yet to learn much about the root CRC-200 systems of perennial plants and of a greater diversity of plants New Orleans, Louisiana 70148 in general. E-mail: julie [email protected]

Ecology, 85(7), 2004, pp. 2054±2055 ᭧ 2004 by the Ecological Society of America

OCEAN BIOGEOCHEMISTRY: AN OVERVIEW OF THE JOINT GLOBAL OCEAN FLUX STUDY

Fasham, Michael J. R., editor. 2003. Ocean biogeochemis- supply, planktonic community structure, and decadal scale try: the role of the ocean carbon cycle in global change. variability, as well as the challenge of incorporating these Global ChangeÐThe IGBP Series. Springer-Verlag, New complexities into numerical models, appear repeatedly York. xviii ϩ 297 p. $119.00, ISBN: 3-540-42398-2 (alk. throughout the text (e.g., Chapters 2, 4, 6, 7, 8, 9, and 10). paper). The concept of biogeochemical provinces, where the dynam- ics of the marine ecosystem respond consistently to large- scale physical and atmospheric forcing, is ®rst presented in The goal of Joint Global Ocean Flux Study (JGOFS) was the Introduction (Chapter 1), examined in Chapter 2, and to understand the processes controlling the time-varying ¯ux- revisited in Chapters 3, 4, 7, 9, and 10. es of carbon into and within the ocean and to enable prediction General frameworks for ocean carbon research are provided of the response of these processes to climate change. The 11 by Chapter 1, ``Biogeochemical provinces: towards a JGOFS chapters of this volume (by 41 authors) evolved from plenary synthesis,'' and Chapter 2, ``Physical transport of nutrients talks at the JGOFS Open Science Conference in Bergen (Nor- and the maintenance of biological production.'' Ducklow way) in 2000 by representative members of the ocean bio- shows in Chapter 1 that JGOFS station-based primary pro- geochemistry community. duction measurements are generally higher than those of the The volume consistently conveys both the importance of corresponding biogeochemical provinces of Longhurst, mod- the ocean in the global carbon cycle and the uncertainty of eled from chlorophyll concentrations measured by the Coastal the oceanic response to global change. The authors coincide Zone Color Scanner (CZCS) satellite. An updated comparison in highlighting various directions of research, such as the with ocean color measurements by SeaWiFS would have been importance of understanding and modeling ocean circulation interesting. The discussion of the regional contrast between (Chapters 2, 5, 6, 7, and 9), re®nements of the de®nition of the relative rates of bacterial and primary production seems the biological pump (Chapters 4, 6, 7, and 10), and uncer- tantalizingly short. Williams and Follows do an excellent job tainties in the length scale of remineralization (Chapters 2, in Chapter 2 of placing nutrient supply and biological rates 5, 6, 8, and 9). Non-Red®eld stoichiometry, atmospheric iron into the context of physical transport and mixing. They use July 2004 BOOK REVIEWS 2055 a broad-based overview of both ®eld and modeling studies euphotic zone''), while those of the ocean bottom are studied to illustrate the key physical processes. by Lochte et al. in Chapter 8 (``Benthic processes and the The initial background on plankton community processes burial of carbon''). Both chapters compare export estimated in the euphotic zone is given in Chapter 4, ``Phytoplankton from different approaches, such as remote sensing/reminer- and their role in primary, new, and export production,'' and alization models, sediment traps, benthic ¯ux chambers, and expanded upon in Chapters 7 and 10, which address the in- the inversion of numerical models. Lochte et al. discuss the terrelationship between biogeochemistry and climate. In advantages and limitations of a suite of paleoceanographic Chapter 4, Falkowski et al. explain the evolution of methods proxies of ocean biogeochemistry. Although outside of the to estimate primary, new, and export production, de®ne the mainstream in JGOFS, this topic takes on incalculable value biological pump, and discuss the role of functional groups when attempting to understand oceanic responses to long- (diatoms, calci®ers, and nitrogen ®xers) in export (these top- term climate change. ics reappear in Chapters 6, 8, and 9). Boyd and Doney present The stated objective of The IGBP Series, to present key an exhaustive and valuable review of the community structure results of the JGOFS project, is accomplished. As to be ex- of the planktonic ecosystem in the context of temporal var- pected in such an interdisciplinary arena, the tone of the iability (Chapter 7, ``The impact of climate change and feed- chapters varies along a continuum between explanation and back processes on the ocean carbon cycle''). Unfortunately, review of current research. Although some chapters tend more the lengthy initial discussion of feedback analysis is not in- towards the ``big picture'' (e.g., Chapters 4, 8, and 9), in most tegrated in the remainder of the chapter and there is no ap- cases the intended audience appears to be peers within the parent distinction between interannual and climate variability biogeochemical or climate change community. Almost all of or between biological response and biological regime shifts. the chapters are appropriate for graduate courses, but most Karl et al. summarize the eight JGOFS-sponsored time-series are likely too complex for the undergraduate level. programs in Chapter 10 (``Temporal studies of biogeochem- Perhaps due to uneven peer review throughout the volume, ical processes determined from ocean time-series observa- there are some science-related typographic errors (e.g., the tions during the JGOFS era''), highlighting ®ndings that can units for Figure 2.10 or the lack of axis labels, symbol iden- only be obtained with multi-year high-frequency sampling, ti®cation, and station acronym identi®cation in Figure 9.11). such as temporal variability in nutrient limitation or event- Although never substantive, there were more errors in spell- driven atmospheric supply of iron. ing and grammar than expected for a publication of this cal- Two chapters address modeling of the ocean carbon cycle. iber. ``Coccolithophorids'' has three mistaken spellings and In Chapter 5 (``Carbon dioxide ¯uxes in the global ocean''), surnames often fared poorly (e.g., Kosro rather than the cor- Watson and Orr show how models and observations of the rect Korso, and Iglesiais-Rodreguez rather than the correct atmosphere and ocean are used to quantify the patterns and Iglesias-Rodriguez). The design of the book is very attractive, variability of oceanic uptake and storage of anthropogenic the type clear, and the ®gure size appropriate. However, iden- carbon. Results from the Ocean Carbon Model Intercompar- tical formatting of the ®rst three levels of headings is occa- ison Project (OCMIP) show the abilities of current models sionally confusing. as well as the uncertainty of future predictions. In Chapter It is disappointing that there is no unifying synthesis chap- 9, Doney et al. illustrate progress in ``Global ocean carbon ter bringing together the research topics that weave through- cycle modeling,'' including models of inorganic carbon trans- out the volume under slightly different guises. Biogeochem- port, models of biogeochemical cycles, and models of eco- ical provinces could have provided an excellent context to system dynamics, by comparing observations and simula- compare export, primary production (all mentions of global tions. Chapter 9 conveys a balanced perspective of the mod- estimates are ϳ45 Gt C except the value of 90 Gt C on p. eling successes, limitations, and future directions. 240 which must refer to gross photosynthesis), or the de®- Three chapters address areas of less traditional emphasis nition of the biological pump. Despite this missed opportunity in JGOFS: continental margins, carbon processes below the to underline the encompassing conclusions and future ave- euphotic zone, and paleoceanographic proxies of biogeo- nues of research, this volume provides a valuable state of the chemical cycles. In Chapter 3, ``Continental margin exchang- art of ocean biogeochemistry for those interested in the car- es,'' the difference in approaches used by Chen et al. to es- bon cycle or climate change. timate carbon budgets for select margins fails to convey an MARY-ELENA CARR effective synthesis. The Eastern Boundary Current section includes a confusing compilation of unrepresentative data (the Jet Propulsion Laboratory, California Institute of Technology primary production values of Table 3.4 are too low for the 4800 Oak Grove Dr. Humboldt and too high for the Canary or California Currents). Pasadena California 91101±8099 The East China Sea, a recycling margin, is extrapolated glob- E-mail: mec@paci®c.jpl.nasa.gov ally without justifying whether it is representative. Carbon dynamics in the ``twilight'' or mesopelagic zone, The opinions stated in this review are not those of the Jet between 100 and 1000 m depth, is addressed by TreÂguer et Propulsion Laboratory, California Institute of Technology, or al. in Chapter 6 (``Water column biogeochemistry below the of the National Aeronautics and Space Administration. 2056 BOOK REVIEWS Ecology, Vol. 85, No. 7

Ecology, 85(7), 2004, pp. 2056±2057 ᭧ 2004 by the Ecological Society of America

RECONCILIATION ECOLOGY, OR RESIGNATION ECOLOGY?THE CHALLENGE OF LIVING WITH NATURE

Rosenzweig, Michael L. 2003. Win-win ecology: how the different areas. A useful rule-of-thumb is that at these broad earth's species can survive in the midst of human enter- spatial scales, the number of species expected to be main- prise. Oxford University Press, New York. 211 p. $27.00, tained in a dynamic equilibrium (including both ecological ISBN: 0-19-515604-8. and evolutionary processes) scales directly with area. In the following chapters, Rosenzweig then draws out the sobering consequence of this conclusion for the science of biodiversity. Walk into any well-stocked bookstore, and you will ®nd He suggests that roughly 5% of the world's terrestrial habitats that its environmental section bulges with jeremiadsÐtomes is currently in a near-pristine form. If all this land were to that describe in depressing and convincing detail the many be instantly protected in reserves from further development, dimensions of the biodiversity disaster looming all around and the remaining fauna and ¯ora completely restricted to us. It is a welcome contrast to read instead a volume that this reserve system, then in the long run approximately 95% frankly admits these sobering facts, yet also champions a of all species would be expected to be lost. This staggering potential strategy for sustaining a reasonable fraction of the magnitude of projected loss is probably an underestimate of earth's fauna and ¯ora. In this gracefully written, thoughtful the potential drain of species from the reserve network, given and timely book, aimed as much at the general nonspecialist the vicissitudes of climate change and the challenge of in- reader as at professional scientists, Rosenzweig sketches a vasive species pressing in from all sides. hopeful vision of the future for biodiversity. The central plank So what is to be done? As Rosenzweig says, ``We must of this vision involves the development of a new subdiscipline abandon any expectation that reserves by themselves, whether of applied conservation ecology, which Rosenzweig dubs pristine or restored, will do much more than collect crumbs. ``reconciliation ecology.'' The basic aim of reconciliation They are the 5 percent. We need to work on the 95 percent.'' ecology is to deliberately design human-dominated habitatsÐ The ®rst few chapters of the book describe a number of ex- those places people live and workÐso as to not shut out the amples where biodiversity is being maintained either delib- rest of life. As the author puts it, a central goal of conservation erately or accidentally in human-dominated landscapes, rang- efforts should be ``sharing our habitats deliberately with other ing from Israeli staging grounds for migratory Palearctic species.'' The book lays out an argument for why this stra- shorebirds, to settling pools at a Florida power plant (within tegic readjustment in our thinking is necessary, and describes which the American crocodile happily resides), to efforts to a number of case studies where the strategy appears to be foster red-cockaded woodpecker numbers on an army base. working. Visionaries and prophets are often a bit hazy when it comes The central dilemma faced by conservation today can be to the practical details of crafting tactics for creating in reality stated quite simply, and Rosenzweig does an excellent job in the world they dream about. This book ®ts squarely in that describing this dilemma in non-technical terms. Most con- tradition, and it would be carping and unfair to criticize it servation biology focuses on the scienti®c and societal di- based on the absence of a detailed coherent program for ex- mensions of identifying and protecting patches of natural ar- ecuting its vision. But it may be useful to re¯ect brie¯y on eas, with the aim of preserving those species now found a few issues that must be addressed, if reconciliation ecology thereÐan agenda of land preservation the author dubs ``res- is not to become merely a prelude to ``resignation ecology,'' ervation ecology.'' In recent years, there has also been a great where we learn to become resigned to living in and coping deal of attention given to reconstituting degraded habitats into with the devastated, defaunated world we are creating at some semblance of their original selvesÐrestoration ecology. breakneck speed. The ultimate combined outcome of these efforts are sets of A central agenda in community ecology today is under- parks and nature reserves, both pristine and restored, scattered standing how patterns of species richness re¯ect the interplay in landscapes dominated by human activity. Rosenzweig com- of regional, large-scale processes and local population dy- pellingly argues that although both reservation and restora- namics and interspeci®c interactions. Making advances in this tion ecology may be necessary components of the conser- agenda, I suggest, is key to developing conservation strategies vation agenda, they cannot be suf®cient, and indeed can only that combine reconciliation with preservation and restoration. achieve the objectives of conservation if combined with rec- For instance, if a species that is largely restricted to reserves onciliation efforts. The reason re¯ects one of ecology's most can utilize a human-dominated landscape to some extent, this general empirical lawsÐthe fact that the number of species creates a buffer that can help mitigate against unexpected increases with area. catastrophes in the reserves (even if the buffer population Elsewhere Rosenzweig has examined species-area rela- itself is not completely self-sustaining). A ``sink'' population tionships in authoritative detail, and in this book in a chapter is not necessarily a complete dead-end, but could play a vital titled ``The tyranny of space'' he crisply revisits this issue, role in long-term persistence. Conversely, mobile species that with an eye towards conservation. The increase of species adapt to and then become abundant in anthropogenic land- richness with area is particularly pronounced when consid- scapes may pose risks to species con®ned to reserves. As an ering units of land that are suf®ciently isolated that immi- example, restrictions on hunting can foster populations of gration does not bolster local assemblages, and that are far large vertebrates, and so might be viewed as a social mech- enough apart that evolution can proceed independently in anism for reconciliation. But in some case this tactic can have July 2004 BOOK REVIEWS 2057 devastating consequences for other species (e.g., white-tailed come from developed countries, where reconciliation may be deer in the eastern United States have burgeoned in numbers readily achieved with only modest impacts upon local econ- and severely harmed native herbaceous plants such as Tril- omies, and where population growth is moderate. Most bio- lium). One potential hazard in piecemeal, species-by-species diversity, however, resides in tropical developing nations, approaches to reconciliation (along the lines of the interesting where local population pressures upon the land is intense and case studies presented by Rosenzweig) is that most of us are mounting, leading to habitats habitable by few living things ill-equipped to predict and monitor the long-term conse- (e.g., much of the upland plateau of Madagascar), and where quences of how a given habitat change will shift relevant there may be few mechanisms in place to withstand the ram- landscape and community dynamics. Moreover, many species pant onslaught of habitat destruction driven by the imper- exist because of large-scale disturbances (e.g., ¯ood regimes sonal, non-local forces of global capitalism (e.g., as in mul- in freshwater communities, severe ®res in prairies and chap- tinational logging and mining operations). It is dif®cult to arral). Articulating how human activity can be made com- imagine how this juggernaut will be slowed, must less mod- patible with the persistence of these large-scale disturbance ulated in the direction of reconciliation, without the deter- regimes is a signi®cant challenge in reconciliation efforts. mined cooperative action of local, national, and transnational Another important issue is that most conservation planning governments and agencies. I thus must disagree on this one takes species' properties as ®xed, and then attempts to iden- point with Rosenzweig, who suggests in the ®nal chapter that tify the set of environmental requirements that permit long- the role of government in reconciliation should be limited. term persistence. Yet as evolutionary biologists, we know that Incentives and restrictions applied by governments can have species evolve in changed environments, and that such evo- profound consequences upon local behaviors. Just imagine lution can in¯uence persistence in a variety of ways. In the what a difference one might see in, say, the mid-western U.S., ®rst chapter of this book, Rosenzweig notes that ``The habitats if federal subsidies to farmers re¯ected a standard of biodi- we create around us will be novel, so the species that we versity maintenance. Maybe instead of sterile homogeneous hope they save will not be particularly well adapted to them.'' Illinois corn ®elds and Kansas wheat ®elds stretching unbro- Yet if we can create persistent populations, then we expect ken, horizon-to-horizon, we could instead enjoy vistas en- adaptive evolution. Making predictions about evolution in riched by scattered hedgerows, copses, and pocket wetlands. changing environments is challenging, but one general con- Despite these caveats, I can warmly recommend this book. sequence can be readily foreseenÐif a species is found both It is peppered with personal reminiscences and touches of in reserves and in human-dominated landscapes, evolution in humor, and it is a pleasure to read. Indeed, I think this book the latter novel environments will occur. Adaptive evolution is a ``must-read'' for conservation biologists, natural resource in these commensal populations can then ®lter back to in¯u- managers, and concerned citizens. ence the traits of populations found in protected reserves, ROBERT D. HOLT with reverberating conseqences in the latter (e.g., on coevo- lutionary processes). Reconciliation ecology will need a hefty University of Florida dose of applied evolutionary biology. Department of Zoology Finally, it is noteworthy that most of the concrete examples Gainesville, Florida 32611-8525 of successful reconciliation efforts Rosenzweig recounts E-mail: [email protected]¯.edu

Submit books and monographs for review to the Book Review Editor, Janet Lanza, Biology Department, University of Arkansas at Little Rock, Little Rock, Arkansas 72204 (telephone (501) 569-3500). We welcome offers to review books for Ecology, but we cannot accept an offer to review a speci®c book. Anyone who wishes to review books for Ecology should send a current curriculum vitae, a description of competencies, and a statement of reviewing interests to the Book Review Editor. Authors of reviews must verify that they have no con¯ict of interest that might interfere with their objectivity, and that they have not offered (and will not offer) a review of the same book to another journal.