between 100,000 to 120,000 ha of rubber plantation in production is needed today to neutralize rubber imports, while the market for cacao is fairly restricted.

Anderson et al. (1985) described and analyzed a commercial AFS with relatively high levels of sustainability that is being developed by riverbank dwellers. This system is based on the extraction of forest products with and without management and is being developed in a periodically inundated várzea floodplain of the Amazon River estuary, in the vicinity of Belém, where it is difficult to use conventional agricultural practices. The main activities in the system include hunting, fishing, raising of small domestic animals, and harvesting of fruits, heart of palm, wood, organic fertilizer, ornamental plants, latex, fibers, oil-bearing seeds, and medicinals. These products are sold in the Belém farmer 's open market. This is an example of a semiextractive agroforestry system in which a proportion of the economically valuable trees in the system are domesticated or semidomesticated.

An important example of sustainable agroforestry agriculture is one developed by Japanese immigrants and their offspring (NippoBrazilian farmers) who have farmed remote forest regions of the Amazon Basin since the late 1920s (Subler and Uhl, 1990). In the mid-1950s black pepper fusariose became the most serious constraint to sustainability of black pepper production, the main activity of those farmers at the time. In the early 1970s these farmers had to diversify their agricultural systems.

Nippo-Brazilian farmers have replaced most of their black pepper agriculture with diverse agroforestry arrangements. Farmers rely on intensive cultivation, producing a diversity of high-value cash crops through mixed cropping of perennial plants. These plants include a wide variety of perennial trees (such as cacao, rubber, cupuaç u [Theobroma grandiflorum], graviola [Annona muricata], papaya, avocado, mango, and Brazil nut) and palms (such as açai [Euterpe oleracea], coconut, oil palm, peach palm), shrubs and vines (pineapple, Barbados cherry [Malpighia glabra], banana, coffee, passion fruit, black pepper, and urucu), and annuals (such as cotton, cowpea beans, pumpkin, cassava, melon, pepper, cucumber, cabbage) (Subler and Uhl, 1990).

Most farms are operated by single families, and the average size is between 100 and 150 ha. On average, however, each farm cultivates only about 20 ha (Flohrschütz et al., 1983). The rest of the area is generally in secondary forest regeneration, following pepper field abandonment or previous slash-and-burn activity, or is undisturbed forest. Figure 7 shows a typical Nippo-Brazilian agroforestry farm in Tomé-Açu.