Tuatara: Volume 30, Issue 1, December 1988
Book Review: — Forest Vines to Snow Tussocks: The Story of New Zaland Plants
Forest Vines to Snow Tussocks: The Story of New Zaland Plants
New Zealand's biota attracts a lot of interest. It features prominently in world literature and is the basis for our strong conservation movement. Much is written about the plants and animals but few authors directly confront the question of why the biota is of such interest. This new addition to the prolific natural history literature is an attempt to shed some light on the “story of New Zealand's plants” from this point-of-view. And, very appropriately, it has been done by the former editor of Tuatara for many years. John Dawson has spent his professional life researching certain groups of plants that occur in New Zealand (especially Umbelliferae and Myrtaceae) and has developed undergraduate and postgraduate courses in advanced Botany which explore the origins and special features of our flora. The book has grown from these courses.
It also owes much to Leonard Cockayne's New Zealand Plants and their Story which was the first attempt to review the distinctive features of native plants and which is now 60 years out-of-date. John Dawson set out to build very closely on Cockayne's model by reviewing the increase in knowledge gained over the past 60 years. It is not a guide book to plant identification but aims to use a representative selection of the larger and more conspicuous vascular plants to illustrate the special features of our flora.
The book is easy to use and enjoyable to browse. Although we are conditioned to colour illustrations in most modern natural history books, this one's reliance on monochrome photographs certainly does not detract from its purpose. The illustrations are copiously spaced throughout the text and very nicely reproduced with good clarity and tonal range. In fact, several now historic photographs from Cockayne's earlier book are reproduced with greater clarity than the originals. The printing layout gives a remarkably wide outer margin, some might say wasteful, but it is utilised to bring variety to each page with figure captions and photo overlaps. The author's style is straightforward, certainly not exuberant and the text is well referenced.
John Dawson's version of the story of New Zealand plants is organised into 12 Chapters, mainly based on a habitat or community approach. Forests, which dominated the New Zealand landscape prior to the arrival of humans, also dominate the book with 4 chapters devoted to the structural features of the plants themselves (roots, flower forms, leaf features) and their associated vines and epiphytes (“the first thing that strikes the overseas botanist”). Characteristics of the major forest types in New Zealand are reviewed with brief notes on specialised communities such as coastal forest, kauri forest, mangroves and swamps.
A particularly interesting chapter discusses the recent debate over possible causal factors behind the divaricating growth habit of so many low shrubs in this country. These impenetrable twiggy shrubs and juvenile trees are a significant feature of our flora and have been variously attributed to harsh climatic factors or the browsing effect of moas. John Dawson provides an intriguing appraisal of these views which should stimulate the non-specialist reader to take an added interest.
Plants of open habitats are segregated into lowland and alpine. A glimpse of the dynamic, ever-changing patterns of vegetation is given in Chapter 7 where the origins page 86 of the drier grasslands and shrublands on the eastern sides of both Islands are discussed. Many New Zealand biologists are probably still unaware that these areas were largely forested in pre-human times. Natural fires and repeated Maori burning, to encourage bracken or flush out moas, allowed invasion by tussocks which created, for instance, the central Otago landscapes we now tend to regard as “natural”. Vegetation of river-beds, cliffs and dunes are presented under the lowland open habitat, as are the specialised plants of serpentine soils.
The section on the alpine flora surveys the main features and highlights some dominant plant types, especially those of scree and rock areas, before considering the strange debate about where the alpine plants came from. I say “strange” because surely most of our plants evolved nowhere else but in New Zealand. The problem is that geologists have told us that New Zealand's present mountains are quite new, only a few million years old and prior to their formation, the land was low-lying for much of its history, with a warmer climate than now. So we are faced with the problem of explaining how a specialised alpine flora, richer in species than the forests, came into being in such a short time. Were the ancestors of the plants already here? Did they reach New Zealand mountains by migrating from Antarctica? Did they get blown here from the mountains of SE Asia, possibly via Australia? A discussion of the views of various authors is presented within a predominantly migrationary framework. Whilst I agree that we cannot rule out the possibility of some immigrants, I must say I prefer Cockayne's whimsical statement, made 61 years earlier, that if the plants could speak “we might learn from some of them that their very remote ancestors were born on New Zealand soil”. In my view, the “alpine problem” will never be resolved by prolonging the discussion of ad hoc explanations, only by adopting a rigorous scientific approach to biogeography.
Two chapters review plants of the outlying islands (subantarctic islands, Chatham, Kermadec, Lord Howe and Norfolk Islands) and comment on the flora of other southern lands. These descriptive accounts focus on genera and species which are of interest to New Zealand. Many readers will be surprised to learn that certain plants are so widely distributed over the islands and lands of the southern oceans and, for example, that tiny Lord Howe Island supports an endemic species of Carmichaelia, the only member of this genus occurring outside New Zealand. The origins and significance of some of these widespread southern plants are discussed in terms of both long-term land continuity and long distance dispersal.
The final chapter, devoted to plant fossils from New Zealand, reveals the wealth of discovery in this field since the time of Cockayne. The botanical history, as told by plant fossils (largely pollen) in New Zealand and its surrounding lands, pieces together a picture very different from today but steadily evolving to the modern pattern. Changes are particularly notable in the distribution of Nothofagus species-groups, the genus Casuarina and the podocarps. In his concluding remarks, John Dawson draws attention to the significance of New Caledonia as a place where the Gondwana biota has survived better than in either Australia (with its aridity) or New Zealand (with its more severe Pleistocene climate), a view with which I agree.
A book which aims to be as comprehensive as this one but is produced with a student budget in mind, cannot fulfil everyone's expectations. Thus, one reviewer has said it leaves untouched the human side of plants, another that it fails to do justice to the functioning and dynamics of plant communities. My own bias is towards historical biogeography so I can add that I would have appreciated more emphasis on recent progress in this field with maps showing evolutionary hypotheses for some of the key plant genera such as Nothofagus. However, John Dawson could never write the perfect book to suit all readers and their particular viewpoints. The fact remains that he has produced a worthy successor to Cockayne's earlier volume page 87 and that its strength lies in the author's own bias towards plant structural features and the floristics of different communities. There is no doubt that it will be an extremely useful reference book for botany and natural history students to gain an overview of our flora. I hope someday we will have an animal book to match it.page breakpage break