Book Review

Abstract

C. Körner (1999) Alpine Plant Life: Functional Plant Ecology of High Mountain Ecosystems Pp. vi + 338. With 243 Figures and 4 colour plates. Springer Verlag, Berlin and Heidelberg, Germany. ISBN 3-540-65438-0. Price £34.00 (paperback). ISBN 3-540-65054-7. Price £61.50 (hardback). Alpine vegetation has always inspired wonder for its floral displays and aroused curiosity for the range of plant types that flourish in such seemingly harsh environments. Human awareness of the distinctive nature of this habitat probably predates history. As pointed out in an opening chapter, the term ‘alpine’ may even be derived from that most ancient stone-age language Basque (Euskera) where the word ‘alpo’ denotes a mountain flank. Christian Körner's monograph has clearly been stimulated by the questions that have been asked by generations of botanists and in particular the many papers that have been written in German during the past two centuries on the botany of the Alps. The author acknowledges in the preface his debt to a century of research into alpine vegetation at the University of Innsbruck. For those who do not read German, this book is therefore an excellent entry into the many pioneering studies on alpine biogeography and geobotany that have been written by past generations of Austrian, German and Swiss botanists. References to this past research is skilfully used throughout the book as a background for many recent studies, particularly in relation to the European Alps. However, despite the intensity of research in the European Alps, there is also extensive coverage of other alpine regions. The mountains of North and South America, of Africa and the Southern Alps of New Zealand have all been visited by Professor Körner, and in many of these places he has carried out his own investigations into the role of temperature in relation to plant growth and survival at high altitudes. A constant theme or leitmotif that runs throughout the book is the need to examine adaptational traits in the environment in which they have evolved, especially when comparing such contrasting conditions as the habitat adaptations of alpine and lowland plants. As we are reminded more than once, examining upland and lowland ecotypes side by side in the same botanic garden or acclimatized growth chamber tells us very little. This point is especially valid in the discussions on the effects of temperature on photosynthesis, respiration, growth, and carbon accumulation. Most commonly, it is pointed out, the lowland condition is taken as the common standard and the metabolic activities of alpine species and provenances are compared with lowland plants in an environment that corresponds to the preferred habitat of the latter. Observations can thus be made under these conditions that alpine plants respire at a greater rate than lowland plants, and that photosynthetic rates are higher in high altitude species. While this is true for this particular lowland situation, and high respiration rates under lowland conditions can explain why alpine plants do nor survive at low altitudes, it does not mean that alpine plants either respire or photosynthesize at a higher rate than lowland plants when in their own preferred montane habitat. The general conclusion, from the author's many studies on temperature and carbon balance in relation to alpine plants and treeline limits, is that the primary processes of photosynthesis and respiration do not provide any answer as to how alpine vegetation is adapted to high altitudes. Instead, it is argued that the key to their survival is to be found in how they invest their assimilates, control their development and adjust their morphology and phenology to maximize their utilization of resources. The book makes refreshing reading for the manner in which it dispels many of the myths that have grown up concerning mountain plants and the position of the treeline, which also has to be understood, as it determines the lower limit of alpine vegetation. Carbon acquisition is shown not to be a particularly limiting factor for alpine plants or even trees. Alpine forbs do not show any systematic change with altitude in their special storage organs such as tubers, rhizomes and thick roots, contradicting a widespread belief that alpine plants, particularly those from regions with short growing seasons invest more in such structures. Alpine plants, it is maintained are well adapted to withstand grazing, at least in the high Alps (if the author had worked in Britain with the present populations of sheep and deer that have impoverished the Scottish flora he might have thought otherwise). Other questions that are discussed in detail include, Why are alpine plants small? The dwarf nature of much of the alpine flora, it is argued, is not due to carbon or nutrient deficiencies, or to small cell size, which has often been considered as an adaptation to frost resistance. In fact, there is a trend in some very high altitude species to have unusually large cells which means that small alpine plant have fewer cells per plant than lowland species. A possible explanation, therefore, is that growth early in the season in cold climates is achieved largely through cell expansion rather than through the more energy demanding process of cell division. Alpine plants are shown to be highly specialized in their adaptations to microhabitat differences on the mountain side. Any species or population living in marginal and environmentally fluctuating habitats clearly has to balance risk against opportunism. The phenological problem of optimizing the timing of the resumption of growth in spring evidently presents a serious problem for plants at high altitudes, where an uncertain expectation of when spring will arrive is coupled with short growing seasons. Species or populations with a phenological delay in resuming growth, although they may escape the risk of injury from late frosts, are likely to lose ground to more precocious plants. Over very short physical distances there can be dramatic climatic gradients depending on snow cover, exposure, aspect, soil type and moisture, and species and ecotypes have evolved distinct and often contrasting strategies to exploit these habitats. The section on alpine land use lets us see that in alpine regions human disturbance has produced beneficial effects in the past and harmful consequences in modern times. The physical fragility of alpine soils and the effects of too much trampling are self-evident. However, species-rich alpine meadows are a product of the practice of transhumance in alpine regions which dates back to the Neolithic and examples cited in this book pose tantalizing questions as to the evolutionary origin of some of their traits. Why do the flowers of hay meadows go through a sharp transition from yellow to white and then to pink and blue at their flowering peak, while those of the neighbouring alpine pastures have white as their predominant colour early in the season and predominantly yellow flowers (Leontodon and Hieracium) in the second half of the summer? The reduction in transhumance that is such a widespread phenomenon at present throughout mountain areas is suggested as probably a greater danger to the biodiversity of alpine plant life than climatic warming. The insidious yet rapid upslope spread of forest cover is likely to bring about a habitat change that will be beyond any hope of reversal if the present degree of abandonment of alpine transhumance continues. Books that provide a mine of information and are yet an enjoyable read are rare. Dispelling of myths in a scientific manner without iconoclastic overstatements is also a positive attribute that makes refreshing reading. The challenge of photographing the smallest plants in the world and succeeding in producing a wealth of black and white high quality images, is also an outstanding accomplishment and Professor Körner is to be congratulated for producing a book that will be both enjoyed and referred to for may years to come.