•A great number of secondary crops are grown together with the main food
crops (Table 8.2).
Unlike wild biodiversity, the agricultural biodiversity of shifting cultivation
crop fields has attracted little attention from ecologists. The result is that
processes that create and maintain this diversity, although they may have been
recorded and appreciated by agronomists and anthropologists, are poorly
understood. This is particularly true for the vegetatively propagated crops that
dominate many shifting cultivation systems, such as banana, cassava, plan-
tains, and sweet potatoes. Several external forces currently threaten the main-
tenance of this local agrobiodiversity, including intensification, commercial-
ization, technological change, and the loss of traditional knowledge. There
seem to be two answers to these threats. One is that genetic erosion is
inevitable and therefore ex situ conservation is the solution (Frankel 1995).
The other is that for several reasons (including site adaptation, risk aversion,
and culture) farmers are reluctant to abandon their landraces or agricultural
practices for new varieties or new practices (Brush 1995; Louette et al. 1997).
In the first view, once landraces have been conserved ex situ, traditional farm-
ers have little importance; in the latter view, in situ conservation continues to
make unique contributions even in a modernized world (McKey 2001). For-
tunately, the “ex situ conservation only” paradigm is moving toward a new,
more balanced, “ex situ and in situ” paradigm. This paradigm shift might
increase the importance of traditional shifting cultivation systems in agrobio-
diversity conservation strategies.
168 III. The Biodiversity of Agroforestry Systems
Table 8.2. The species cultivated in shifting cultivation.
Number of
Cultivated
Species Ethnic Group Country
Asia
50–200 Kenyah Sarawak, Kalimantan
413 Harunôo Philippines
66 Daribi Papua New Guinea
144 Yopno Papua New Guinea
America
38–41 Yanomami Brazil, Venezuela
38 Andoke Colombia
71 Yekwana Venezuela
Africa
34 Badjwe Cameroon
38 Mvae Cameroon
37 Tikar Cameroon
40 Ngbaka Central African Republic
Source:Modified from Dounias (2001).