ASBS Newsletter – Book Review

The Ecology and Biogeography of Nothofagus Forests

edited by Veblen T. T., Hill, R. S. & Read, J.

(From ASBS Newsletter Number 91, June 1997)

Published by: Yale University Press, Yale. (1996), pp. 403.

This splendid book opens with the words 'The unifying theme of this book is its focus on change in Southern Hemisphere Nothofagus forests'. Not only does this book achieve the task of portraying the changing Nothofagus forests through time and space, but it also unveils the changing hypotheses and perceptions that historically scientists working on Nothofagus have held. Nothofagus is so often used as the key Gondwanan link in biogeographical studies, yet discussions of long distance dispersal in the family are now eroding away the almost mythical status that these plants once held. This is not to say that this family is no longer a critical player in the biogeography game, in fact this book elegantly and in minute detail, demonstrates that the importance of the genus goes beyond only this notoriety.

Almost everything that is currently known about southern Nothofagus forests, both past and present has been said in this book. The 403 pages are a testament to the interest that this genus has created. This book really is a one stop shopping place for scholars of Nothofagus and southern forests. One of the extremely appealing aspects of this book is its integration of an ecological and historical perspective on southern vegetation change. The introductory and concluding chapters are inspired lessons, setting a standard for others on how to portray to the reader, the possibilities that integration of concepts and themes can achieve. For me they are the icing on this rich cake; definite reading material for the novice and professional alike.

The introductory chapter covers themes such as: temporal and spatial scales of vegetation dynamics, paradigm shifts in successional theory, disturbance and the patch dynamics perspective, microscale climatic variability and vegetation change, macro- and megascale vegetation change (including climate change, photoperiod, carbon dioxide levels and changes in landmass position) and biodiversity and conservation. Chapter 2 sets the evolutionary perspective discussing current beliefs on the origin and diversification of the genus. The authors comment that the argument for the recognition of Nothofagaceae rests heavily on the difference between the origin of Nothofagus cupules and those of other fagaceous genera (Nixon 1989), but that the most recent infrageneric classification (Hill & Read 1991) now rationalises the formal taxonomic division of Nothofagus with well established, but recently revised pollen groupings (Dettmann et al. 1990). Possible centres of origin predict either the southern South America-Antarctic Peninsula region or the Southeast Asian Australian region, with the first currently being the more supported hypothesis. The early diversification and migration discussion is very interesting, highlighting the point that fossil Nothofagus pollen is so abundant and well known that its absence from Africa and India is one of the few cases in which 'negative evidence' in the fossil record is of major importance.

Of all the detailed information this book provides one of the most stimulating paragraphs that the book provides is to be found on page 17. 'One of the important features of Nothofagus to biogeographers is its extremely poor fruit dispersal (Rodway 1914, Preest 1963), suggesting that land-based dispersal was the only option for the genus. Recent pollen evidence (Macphail et al. 1994) strongly suggests that rare long distance gene flow has occurred over the Tasman Sea from Australia to New Zealand during the Cenozoic... Independent evidence from nucleotide differences between the closely related N. moorei (Australia) and N. menziesii (New Zealand) supports speciation, substantially postdating the separation of the two landmasses (Martin and Dowd 1988) and the cladistic analysis shown is also consistent with this hypothesis. If long-distance dispersal of Nothofagus, either by fruit dispersal or perhaps by live whole trees or parts of trees that floated between landmasses and established vegetatively, was a repeated (if rare) phenomenon, a major reinterpretation of Nothofagus biogeography will be required.' Now if that isn't putting a fly in the supporters of vicariance, land-based dispersal ointment I don't known what is. The long distance dispersal banner is flown high in several chapters and for me is one of the most thought provoking ideas to come from the book, but it is only one of many. There is so much detail about Nothofagus written on the pages of this book, its a pity that the font size is just a tad small, because its the sort of book you find hard to put down. The buff coloured paper is a nice touch though and the figures and tables are clear and very well presented and the headings are pertinent and informative. If you hunger for detail, this book will satiate your appetite.

Chapter 3 discusses the ecology of New Zealand Nothofagus forests, covering topics such as New Zealand geography, the taxonomy of the four species and their geographical distribution, the distribution of these species along environmental gradients, comparative life histories, disturbance regimes in beech forest areas, forest associations, productivity and nutrient cycling, associated biota and the trophic web and beech forest management. Chapter 4 leads the reader through the history and palaeoecology of New Zealand Nothofagus forests, discussing the fossil taxa, pollen dispersal, Cretaceous, Tertiary and Quaternary history, the controversial Nothofagus gaps and postglacial spread, and the effects of fire and volcanism. Again evidence is presented which suggests that Nothofagus has crossed substantial ocean gaps at times in the past. McGlone, Mildenhall and Pole so rightly point out that there are probably many other species with impeccable Gondwanic inheritance, which have undergone long distance dispersal, particularly to New Zealand and why should so much emphasis be placed just one attribute, presumed poor seed dispersal. Indeed the 'experiments' that created the legend, by today's standards, don't hold water, so to speak.

The ecology of Australian Nothofagus forests is well documented by Read and Brown, discussing habit and distribution of the three species, the determinants of cool temperate rain forest boundaries and distribution, phenology and reproductive biology, physiological ecology, regeneration and population dynamics, biodiversity of Australian Nothofagus forests, conservation and utilisation. Hill, Jordan and Macphail write an excellent chapter on the history and palaeoecology of Australian Nothofagus forests, reflecting on the role of Nothofagus in the past Australian vegetation, dispersal again supporting the long distance dispersal debate, finding there is no consistent pattern to the time of first appearance in New Zealand, data which clearly suggests an important role for long distance dispersal from Australia to New Zealand. They discuss evolutionary trends amongst the beautifully preserved and illustrated macrofossils, which includes leaves, cupules and fruits.

The next four chapters described elements of the ecology and history of the other three regions of high Nothofagus diversity; New Guinea and New Caledonia and South America, comprising Central Chile, Southern Chile and Argentina. The fascinating past and present story of the fourteen species which occupy the New Guinea highlands and the five different low altitude New Caledonian species is well documented in Chapters 7 and 8. Read and Hope suggest that the gradient in latitudinal occurrence of this group of plants, provides ,natural experiments' that may provide insights into adaptation of morphology and ecophysiology to climate and soil, as well as differences in community structure and species richness. They suggest that Nothofagus is therefore a key taxon, not only in its contribution to studies of palaeoecology and biogeography, but also in its potential contribution to studies in ecophysiology and ecology. The integration of knowledge acquired from all four of these aspects is surely an example which should be attempted for other plant groups too.

History and palaeoecology of the South American Nothofagus forests is described in Chapter 11. Nine fossil Nothofagus plant associations are distinguished in southern south America from the Cretaceous through to the late Tertiary. These nine groups are then placed into four major groups: the Cretaceous, mixed flora, subantarctic and open forest groups, of which the temporal sequence appears to coincide with major periods of environmental change. An interesting comment appears on page 376, that these ecosystems were probably not affected by major changes in photoperiod and thus may be considered as a reference point for other Gondwana land areas. As we delve into the climate change debate, knowledge of the possible affects of changes in photoperiodicity on a megascale may indeed require further investigation.

Finally the last chapter attempts to reaffirm the role of Nothofagus as a 'key genus' (van Steenis 1971) for understanding the biogeography and ecology of the Southern Hemisphere. The arguments are well supported and there are many very pertinent issues raised. I believe that the whole book sells the message of the importance of the past and present southern Nothofagus forests and promotes thoughts for future research and inquiry. All of the contributors are to be congratulated, as are the editors for the excellent task they have done. The Ecology and biogeography of Nothofagus forests belongs on the shelf of every student of Nothofagus, southern forests, biogeography and evolution. One of my concluding thoughts as I was finishing the book was, how will the next version of such a work portray the southern forests. Even since the publication of this book deciduous Mid Eocene Nothofagus leaves have been described from Western and South Australia (Scriven et al. 1995) and the relationships between climate change and Nothofagus evolution in Tasmania has been discussed (Scriven & Hill, 1996). There is an every increasing pool of knowledge forming with respect to Nothofagus. How will our perceptions of the key genus Nothofagus change in the future?

Reviewer: Leonie J. Scriven
Royal Tasmanian Botanical Gardens
Queens Domain, Hobart, Tasmania 7000

References

Dettmann M.E, Pocknall D.T, Romero E.J & del C. Zamaloa M. (1990). Nothofagidites Erdtman ex Potonie 1960: A catalogue of species with notes on the paleogeographic distribution of Nothofagus BL (Southern Beech). New Zealand Geological Survey Palaeontological Bulletin 60: 1-79.

Hill, R.S & Read J. (1991). A revised infrageneric classification of Nothofagus (Fagaceae). Botanical Journal of the Linnean Society 105: 37-72.

Macphail, M.K, Alley, N., Truswell, E.M. & Sluiter, I.R.K. (1994). Early Tertiary vegetation: evidence from spores and pollen. R.S. Hill (ed.), History of the Australian Vegetation: Cretaceous to Recent. Cambridge University Press, Cambridge, pp. 189-262.

Nixon, K.C. (1989). Origins of Fagaceae. In P.R Crane and S. Blackmore (eds.), Evolution, Systematics, and Fossil History of the Hamamelidae, Volume 2. 'Higher' Hamamelidae. Systematics Association Special Volume No. 40B, Clarendon Press, Oxford, 23-43.

Martin, P.G. & Dowd, J.M. (1988). A molecular evolutionary clock for angiosperms. Taxon 37: 364-377.

Preest, D.S. (1963). A note on the dispersal characteristics of the seed of the New Zealand podocarps and beeches and their biogeographical significance. In J. L. Gressitt (ed.), Pacific Basin Biogeography. Bishop Mueum Press, Hawaii, pp. 415-425.

Rodway, L. (1914). Botanic evidence in favour of land connection between Fuegia and Tasmania during the present floristic epoch. Papers and Proceedings of the Royal Society of Tasmania 1914: 32-34.

Scriven, L.J. & Hill, R.S. (1996). Relationships among Tasmanian Tertiary Nothofagus (Nothofagaceae) populations. Botanical Journal of the Linnean Society 121: 345-364.

Scriven, L.J., McLoughlin, S. & Hill, R.S. (1995). Nothofagus plicata (Nothofagaceae), a new deciduous Eocene macrofossil species, from southern continental Australia. Review of Palaeobotany and Palynology 86: 199-209.

Steenis, van C.G.G.J. (1971). Nothofagus, key genus of plant geography, in time and space, living and fossil, ecology and phylogeny. Blumea 19: 65-98.

[The above review first appeared in Southern Connections Bulletin No. 11. We thank Bob Hill (editor) and Leonie Scriven for permission to reprint it. (Eds.)]