Alpine Plant Life: Functional Plant Ecology of High Mountain Ecosystems

Alpine vegetation has always inspired wonder for its ̄oral displays and aroused curiosity for the range of plant types that ̄ourish 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 stoneage language Basque (Euskera) where the word `alpo' denotes a mountain ̄ank. Christian KoÈ rner'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 KoÈ rner, 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 eects 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 ̄ora 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 ̄ora, it is argued, is not due to carbon or nutrient de®ciencies, 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 Journal of Ecology 2000, 88, 727±731