Alternatives to Slash-and-Burn 355Forests
Undisturbed or so-called primary forests are rare in and around the benchmark
sites. Disturbed forests, with some degree of logging, are dominant, with the inten-
sity of logging low in Cameroon, where a few trees are harvested per hectare,
intermediate in Brazil and Peru, and high in Indonesia and Thailand. Extractive
reserves, where non-timber forest products are harvested, are perhaps best known
in the Amazon, where Brazil nuts or castanha (Bertholletia excelsa Humb. & Bonpl.)
and rubber are harvested from naturally occurring trees, but at all sites some
amount of nontimber forest products is harvested from forests of the different
categories. The concept of sustainably managed community-based forests is being
developed at the Brazil benchmark site by Embrapa. Community-protected sec-
ondary forests are found in the Thailand site and in Sumatra, Indonesia.
Complex agroforests
Complex agroforests contain a wide variety of economic plant species and usually
have a rotation time greater than 20 years. The complex agroforests of Indonesia
are indigenous systems established over generations by local peoples living at the
margins of tropical rainforests in Sumatra, Borneo and other islands (Torquebiau,
1984; Foresta and Michon, 1994). Primary or old secondary forests are slashed
and burned, food crops, citrus and robusta coffee (Coffea canephora Pierre ex
Froehner) are planted along with several trees species, and natural regeneration of
forest species is allowed. The trees eventually shade out the crops, occupy different
strata, and produce high-value products such as fruits, resins, medicines and com-
mercially valuable timber. The main economic tree species include damar (Shorea
javanica Koord. & Valeton), durian (Durio zibethinus Murray), duku (Lansium
domesticum Corr.) and rubber. In the case of rubber, production declines after 20
or 30 years, and the slash-and-burn cycle typically begins again; some of the other
tree species, notably damar, can have much longer cycles. Alternatively, agroforests
can be managed with gap replanting that eliminates the need for subsequent slash-
and-burn cycles. In either case, such agroforests, composed of hundreds of small
plots managed by individual families, occupy large contiguous areas in Sumatra
and can be mistaken for forests to the untrained eye. Biophysical scientists have
documented the high productivity and ecosystem services provided by these agro-
forests (Michon and de Foresta, 1996; Michon, 1997). Plant diversity in the
mature complex agroforests is on the order of 300 species/ha, which approximates
that of adjacent undisturbed forests (420 plant species/ha). The richness of bird
species in mature agroforests is approximately 50 per cent that of the original rain-
forest, and almost all mammal species are present in the agroforest (Foresta and
Michon, 1994). The villagers in Krui, Lampung Province, who make a living from
these complex agroforests, have an obviously higher standard of living than those
neighbours who grow only food crops (Bouamrane, 1996).
Complex agroforests based on cacao (Theobroma cacao [Linn.]) as the major
cash crop have been developed in humid forest margins of West Africa over the past
century (Duguma et al, 2001). Jungle tea (Camellia sinensis [L.] Kuntze) complex