Agroforestry and Biodiversity Conservation in Tropical Landscapes

ative connotations, is appropriate because of the use value many such species

have to rural people. Weeds, particularly herbaceous species, are potentially

important sources of nontimber products in shifting cultivation landscapes

(Table 8.3). Indeed, several studies have shown that disturbed neotropical

plant communities contain more individuals of more useful species than

undisturbed forests and produce a greater diversity of products that are more

likely to be familiar to and used by rural people (Voeks 1996; Chazdon and

Coe 1999). The regeneration of some valuable light-demanding tree species is

an important element of the consideration of the weed community of crop

fields and fallows. Examples of such species, which may be actively encouraged

by farmers, are Platonia insignis,valuable for fruits (Shanley et al. 1998), the

multiple use Ingaspp. (Pennington and Fernandes 1998; Unruh 1988; B.

Finegan, pers. obs., 2000), and timber trees such as the widely distributed

Jacaranda copaia(Unruh 1988; Finegan 1996; Finegan, pers. obs., 2000) and

the western Amazonian Guazuma crinita(Smith et al. 2001). A complete

review of this subject is beyond the scope of this chapter, but the potentially

high utilitarian value (Chazdon and Coe 1999) of the taxonomic and

8. The Biodiversity and Conservation Potential of Shifting Cultivation Landscapes 171

Table 8.3. Examples of typical weeds of crop fields and young fallows
in the neotropics.

Family Genus or Species Observations Uses Source

Amaranthaceae Amaranthus hybridus Pantropical Genus: F 1,2

Amaranthaceae Iresine celosia Genus: M 1, 3, 8

Asteraceae Bidens pilosa Pantropical 1

Asteraceae Eupatorium cerasifolium 4, 5

Cyperaceae Cyperus, Scleria

Euphorbiaceae Phyllanthus urinaria, Species introduced Genus: F, M, P 3, 5, 7
Phyllanthusspp. from Asia

Loganiaceae Spigelia anthelmia Species: M, P 1, 3, 6, 7, 8

Phytolaccaceae Phytolacca Genus: F 1,3

Poaceae Andropogon bicornis 5

Panicum laxum America and Africa 4

Paspalum decumbens 5

P. conjugatum Pantropical 1

Rubiaceae Borreria latifolia, B. verticillata:M 4, 7, 8
B. verticillata
Abbreviations:F, food; M, medicine; P, poison.
Sources:1, Rico-Bernal and Gómez-Pompa (1976); 2, Judd et al. (1999); 3, Mabberley (1987); 4, Uhl et al.
(1981); 5, Uhl (1987); 6, House et al. (1995); 7, Grenand et al. (1987); 8, Croat (1978).