Atlas of the potential vegetation of Ethiopia

Abstract

Floras and vegetation maps are the basis of understanding the ecology and botany of every country. Engler published the first map of the vegetation of Africa in 1882, defining the separation of African vegetation into firstly the forest regions, and secondly grasslands and wooded grasslands, a basic distinction that not surprisingly has remained intact. He refined his concepts over the years, putting the work into an evolutionary and phytogeographical context with his field research, particularly in East Africa, publishing a particularly important paper in Annals of Botany (Engler, 1904). Over the last century, floras for both African regions and individual countries have been published, with the Flora of Ethiopia and Eritrea, published over the period 1980 to 2009 by Swedish Science Press, including an up-to-date and thoroughly revised treatment of the diverse species that occur in these tropical but topographically diverse countries. With the increasing linkage of taxonomy with biogeography and ecology, it has now become common that vegetation maps are produced along with floras. This new comprehensive and well-researched volume by Friis et al. fills the need for a high-quality (1 : 2 000 000 or 5 cm : 100 km, with 90 × 90 m resolution) vegetation map of Ethiopia for land-use planning, natural resource management, agricultural development and conservation. Sadly, an important group of uses will also be to track the destruction of vegetation, areas where the ‘potential’ vegetation of the title is no longer present, and the effects of change in climate, and for this the Atlas sets an essential reference point. As with any field project, geographical information systems (GIS) and digital mapping have revolutionized the production of works such as this, particularly in large countries such as Ethiopia where the vegetation zones may be relatively small and with complex boundaries. In this case, much of the country is covered by the Ethiopian highlands, which lie mostly between 1300 and 2000 m, rising to over 4500 m. At lower elevations, the country includes the northern end of the Great Rift Valley, part of one of the major ecosystems of Africa. The first section of the book gives a 13-page review of details of the geography, geology and climate of the country, and this is followed by accounts of the methods used, the history of the vegetation and its study. These do provide an outstanding introduction to the country and I would recommend reading them to anyone visiting Ethiopia with interests in the natural environment. In the second section of the book there are formalized and detailed, but admirably concise and readable, descriptions of the 12 major vegetation types that are recognized, along with their sub-types. The authors nicely balance the distinction of indicator species between constancy and fidelity, with an appendix detailing occurrence of woody species in each recognized vegetation type. Conservation and erosion issues are discussed within the vegetation sections, although from my own interests I would have liked to see a little more about the crops that are characteristic of each zone and perhaps the invasive species. The final section of the book includes the maps themselves. These, with a scale of 1 : 2 000 000, are appropriately detailed with respect to the vegetation types. I am sure it will be no difficulty for the specialist who will mostly make use of the Atlas, but as a recent casual visitor to the country, I would have found it useful to have had coordinates along the axes to avoid juggling of road maps too! The volume is very nicely produced, with well over 100 colour illustrations, mostly filling a half-page, which give an immediate impression of the nature and structure of each of the vegetation types. Apart from the vegetation maps, it also has about 20 maps of various environmental and geographical features, and reproductions of earlier vegetation maps. A minor criticism of many maps is that the shades of colours are very hard to correlate with the legends, and quite impossible to follow in a dark hotel room. Maybe consideration should be given to combining the shades with a numeric key, as is done in the British Geological Survey maps. While most book reviews require some consideration of the readership, I expect this book has a well-defined audience: any organization involved in land-use, development, agriculture, tourism as well as plant taxonomy should have a copy available. It is a very high-quality study of the vegetation of Ethiopia, filling a significant gap. As such the volume should find a place in all libraries that cover the geography and land use of the continent, as well as herbaria with East African collections. I certainly found it an invaluable reference while driving and flying around parts of the country.