- Dispersal Ecology and Evolution ed. by Jean Clobert et al.
Jean Clobert, Michel Baguette, Tim G. Bento and James M. Bullock (eds) 2012. Oxford, U.K.: Oxford University Press. $74.99 paperback; $41.99 eBook. ISBN: 978-0-19-960890-4. xxxiii + 462 pages.
“Here, there, everywhere.” The Beatles anthem is good shorthand for some of the central problems of dispersal and their relationship to the science and practice of restoration ecology. We each work on small patches of the earth, yet each patch is linked in some ways to adjacent areas and to the wider landscape. Each species has their own distinct dispersal profile, driven by evolutionary history and by the peculiarities of habitat and geography for each project site.
There are many consequences of dispersal which are critical to understanding if our restoration projects will succeed or fail to persist. Not all problems can be blamed on our contractors. As population ecologists, we know that dispersal is intimately tied in with all levels of ecological function. Population growth, initiation of new populations, structure of communities, interplay of habitats across the broad landscape, and ecosystem processes are all intimately associated with dispersal dynamics.
This comprehensive, 35 chapter book by Clobert and his associates has many sections which are critical and urgent for restoration ecologists. Although some of the book is deliciously scientific with graphs and theoretical insights which may be tangential to the work of most restoration practitioners, there are lessons learned and warnings here which must play a role in each of our projects. For example, the now classic work by Hanski on Glanville Fritillary butterflies shows the elegance of learning to understand how one butterfly moves about the landscape and how local populations influence others in the region. This detailed long-term work, supported by several books by Professor Hanski, started a wide concern of metapopulation dynamics which now are an important part of the restoration world. Other chapters in the book deal with a wide range of taxa including spiders, toads, composite weeds, lizards, and other vertebrates. Habitats of concern include nature preserves, but also small weedy patches in our urban areas (chapters on Crepis sancta in Europe).
The many authors, including many from Europe, review the origins and causes of dispersal, with a strong emphasis on how dispersal dynamics are plastic. That is, they vary in different landscape settings and habitat structures. The concept of “dispersal kernels” is discussed at length. This focus reconsiders dispersal, not simply as the maximum distance that an offspring, a seed or nestling, travels from its natal home, but as a more accurate statistical distribution of how far a seed or juvenile cohort travels. Think of a scattering of buckshot across the landscape. What is the density of shot on the ground when all pieces land? The dispersal kernel concept is a more robust and useful statistic as it tells restoration ecologist where and how many new individuals will appear in the next generation.
Part VI of this book is an important complex of chapters on climate change and how the process of dispersal can or cannot answer the stress of new climate in any one location. This is one of the great challenges for all modern restoration ecologists as we can only poorly predict what the climate stresses will be in any one location. As so many have written, understanding what is past for our project sites may be a weak predictor of what the future will be like. Restoration in a changing climate is one all practitioners now do, and reiterating past habitats is no longer the prudent approach that each project design should take.
Part VII of this book is a sophisticated discussion of dispersal in habitats which are highly fragmented. Most human dominated land is fragmented, with construction and infrastructure slicing through habitat parcels. Restoration sites are not highly connected as a rule, and dispersal of different taxa across these many barriers is necessary for biotic communication among sites and for persistence against future insults to any one site. This section has case histories of vertebrates, butterflies, and forest herbs. Consequently, these discussions are of interest...