Ecology and Development Series No. 10, 2003 - ZEF

Current state of knowledgeBroader attempts to understand the country’s forest vegetation and itsclassification were made during the second half of the 20 th century. Some researchersassessed the vegetation classes subjectively based on the similarities in geographicaldistribution to the other East African countries (e.g., Hedberg 1951; Coetzee 1978), whileothers (Hamilton 1982) based their classification on altitude and moisture distribution. Themost significant early contributions to the classification of the vegetation of Ethiopia werethose of Pichi-Sermolli (1957) and von Breitenbach (1963). Pichi-Sermolli’s work was theearliest and most detailed map of the vegetation types of Ethiopia (Friis 1992), coveringalso Djibouti, Eritrea and Somalia. He recognized 24 vegetation units. Most of thevegetation units are physiognomic. This system was used to compile the first AETFATvegetation map of Africa (Keay 1959). Later, von Breitenbach (1963) published a moredetailed vegetation map of Ethiopia, building upon the same system. The boundaries of thevegetation maps of von Breitenbach are quite similar to those of Pichi-Sermolli, except forthe differences in the terminologies for naming the vegetation types (Friis and Sebsebe2001). The main difference between this classification and that of Pichi-Sermolli is that it isa much more detailed and rigid classification, based on physiognomy in relation to altitude,humidity and presumed stage of succession (Friis and Sebsebe 2001). Von Breitenbachused seven vegetation categories for mapping, which he further classified into 82, providingcomplex and detailed vegetation types, mainly based on “associations”. Classification ofvegetation into “association” based on presumed stage of succession at certain altitudes anddegrees of humidity, differs in concept and methodology from the ‘association’ commonlyused by the Zurich-Montpelier School of phytosciologists (Braun-Blanquet 1932; Westhoffand Van der Maarel 1978). The system of Von Breitenbach is poorly documented and lacksessential information on locations and distribution (Friis et al. 1982).The most widely accepted system of vegetation types for Africa is that ofGreenway (1973), which was adopted for the vegetation map of southwestern Ethiopia(Friis et al. 1982). This system is physiognomic, and can also easily accommodate a moredetailed system based on “associations”. It was also used as a basis to produce the secondvegetation map of Africa and the accompanying descriptive memoir (White 1983).10