Five thousand years of sustainability? A case study on Gedeo land use

The design of Gedeo "agroforests" is analyzed. Agro-ecosystem components are divided into core and subsidiary types. The first type has a pacemaker role (regulation of agroecosystem rhythm), a spacemaker role (provision of biotope space for other components) and/or placemaker role (provision of living space, or niche for other organisms). The core components are represented by ensete (Ensete ventricosum (Welw.) Cheesman MUSACEAE) and various species of multi-purpose trees and shrubs. These therefore act as cornerstones, holding the whole agro-ecosystem intact. Components with a subsidiary role represented by annual crops, coffee or farm animals are regarded as "fillers", to wit organisms with supportive role. Gedeo land use represents a pre-existing universal ancestor of which modern-day specialized forms of land use (forestry, horticulture or agriculture) are descendants. Farmers employ a holistic management keyed to this agroecosystem complexity. Thus, farmers manage agro-ecosystem complexity, in ways that increase biotopes for "useful" organisms and decrease biotopes favoring pest or disease organisms. This holistic management is different from the "management of biodiversity" as if it were a more or less independent agro-ecosystem property responsive to direct measures. By choosing ensete and trees as basic building bolocks of their "agrogforests", farmers have made a crucial step that staves off hunger, in a mountainous terrain otherwise liable to erosion by rainwater ,to drought or to famine. 4.1. Background The present chapter deals with agro-ecosystem architecture, i.e., the spatial and temporal organization of interacting parts. Interacting parts consist of the domesticated biophysical environment at different levels, crop fields, populations of crop plants and individual crop plants and/or animals. The whole Gedeo zone having three altitudinal agro-ecological zones as subsystems is viewed as a landscape, the system at the highest level. Crop fields within each of the three agro-ecological zones together with the crop components are analyzed as systems at the lower level. How at each system level data are transmitted from a level below it to a level higher up or vice versa, is explained in chapter three. The present chapter as a whole defines agro-ecosystem complexity. The document by Kippie (1994) shows the elements of the basic design for Gedeo land use. The all-inclusive nature of this design, integrating diverse farming systems, crops and animals into one indivisible whole (ch.2), differentiates Gedeo land use from other ensete-bascd systems in Ethiopia (Westphal, 1974; Asnaketch, 1997; Bezuneh, 1996; McCabe, 1996). This complexity can only be explained by examining the farm design, using the systems outlined in chapter 3. This approach is close to the viewpoint of Oldeman (1990), advocating management of agro-ecosystem complexity. Since crops like ensete are emphasized, Gedeo land use design also relates to unity in diversity. This is well illustrated in Kippie's system of multiple rotations. There is a selection of crops with above-average performance, to wit the building blocks of the agro-ecosystem. This in turn invokes such concepts as