356 Agricultural Revolutions and Change
agroforests occur in North Thailand, where the naturally occurring tea trees are left
when the forest is cleared and fruit trees are interplanted. Jungle rubber is a com-
plex agroforest occupying 3 million ha where most of the rubber is produced in
Indonesia. Indigenous Bora communities of the Peruvian Amazon establish com-
plex agroforests by interplanting trees in upland rice and cassava crops (Padoch
and de Jong, 1987). Economic trees include peach palm (Bactris gasipaes Kunth)
for fruits and heart of palm, Inga spp. for fruits and firewood, arazá (Eugenia stipi-
tata McVaugh) for fruit, and timber trees such as mahogany (Swietenia macrophylla
King) and tornillo (Cedrelinga cataeniformis Ducke).
Simple agroforestry systems and intensive tree-crop systems
Simple agroforestry systems usually contain fewer than five economic plant spe-
cies, whereas tree-crop plantations include only one. Both systems may include a
leguminous crop cover. These systems are common in many parts of the humid
tropics, particularly where infrastructure is well developed. Nevertheless, most of
these start with slash-and-burn, in some cases followed by food crops interplanted
with tree seedlings. Intensive tree-crop systems include the classic monoculture
plantations such as oil palm and rubber, timber plantations such as pine (Pinus
spp.), Eucalyptus spp., and cypress (Cupressus spp.), and fast-growing pulpwood
plantations such as Acacia mangium and albizia (Paraserianthes falcataria [L.] I.
Nielsen). These systems can be vast and run by corporations or run by individual
smallholder farmers.
Simple agroforestry systems have less plant diversity than complex agroforests,
higher levels of management are needed, and the regeneration of forest species is
restricted. Included in this category are shade coffee, cacao and coconut planta-
tions found throughout the humid tropics and the peach palm-based systems in
Latin America. A slightly more diverse system based on peach palm, Brazil nut
(Bertholletia excelsa), and cupuaçú (Theobroma grandiflorum [Willd. ex Spreng.]
Schum) has been developed at the western Brazilian Amazon site.
Food crop–fallow rotations
Traditional shifting cultivation with long-term fallows was only found in the
southern reaches of the Cameroon benchmark site and is absent in or disappearing
from the other sites. Fallows of 10 years or less are more common at the other sites
and include either natural secondary forest fallows or managed fallows (Sanchez,
1999). In the northern parts of the Cameroon benchmark site, shortening of the
fallow period has resulted in the invasion and dominance of the bush Chromolaena
odorata (L.) R. M. King and H. Robinson, a member of the Asteraceae family.
Improved or managed fallows, where trees are planted into the fallow, are now
being tried in some of the benchmark sites. The planted trees often are nitrogen-
fixing legumes that restore soil fertility more rapidly and include Inga edulis Mart. in
Brazil and Peru or Calliandra calothyrsus Meissner in Cameroon. Deliberately planted
fallows of Tithonia diversifolia (Hemsl.) Gray, another Asteraceae, are commonly
found in the uplands of South-East Asia, practised by indigenous communities