as vegetation and landscape structure, special habitat features, resource avail-
ability, and hunting pressure. Less information is available on vertebrates than
on plants, however (Shankar Raman et al. 1998). Published studies vary in the
ages of fallow or secondary forest studied and in the characteristics of the sur-
rounding landscape in terms of factors such as the total area of primary forest.
The important influence of the surrounding landscape is acknowledged by
authors such as Shankar Raman et al. (1998) for the specific case of shifting
cultivation and by Saunders et al. (1991) as a general principle, but is not
assessed quantitatively in most studies of shifting cultivation. Nevertheless, the
available information indicates that differences of vertebrate diversity and
composition between fallow stands and landscapes on one hand and primary
forest on the other often are not as clear-cut as they are for plants. This differ-
ence results from factors such as the mobility of vertebrates and the provision
of resources such as food in plant communities of widely varying structural
and compositional characteristics.
Six-year-old fallows of 0.9–2.9 ha in a primary rainforest matrix in lowland
Chiapas, Mexico, did not differ from primary forest with respect to the species
richness of small and medium-sized mammals (Medellín and Equiha 1998).
All the mammal species recorded in traps were found in both habitats,
although differences of relative abundances between habitats were recorded.
Two monkey species were among those described as obligate arboreals and
absent from the fallows (Medellín and Equiha 1998). Shankar Raman (1996)
found that two primarily canopy-dwelling squirrel species were absent from
fallows less than 25 years old in a tropical moist forest landscape of northeast-
ern India. Switching the focus specifically to primates, Cowlishaw and Dun-
bar (2000) observe that the large areas of woody vegetation that persist in
shifting cultivation landscapes may offer adequate habitat for many species of
this group. Tropical studies often show no differences of richness and compo-
sition between primates observed in fallow and secondary forest vegetation
and primary forest, and some primates are more abundant in the anthro-
pogenic vegetation than in “natural” communities in Asia and Africa
(Cowlishaw and Dunbar 2000). Shankar Raman (1996) and Medellín and
Equiha (1998) nevertheless show evidence that as in the case of birds (dis-
cussed later in this chapter), the species composition of mammal assemblages
using fallow vegetation will change over time, at least under some circum-
stances.
At a more general level, studies in Africa (Wilkie and Finn 1990; Thomas
1991; Lahm 1993) have shown that shifting cultivation landscapes may sus-
tain a high biomass of small to medium-sized mammals and sometimes large
ones (buffalos, Syncerus caffer;chimpanzees, Pan troglodytes;gorillas, Gorilla
gorilla;large antelopes; and bush pigs, Potamoecherus porcus) as well. Elephants
(Loxodonta africana) are found in greater numbers in these landscapes than in
areas with greater proportions of primary forest land (Barnes et al. 1991).
174 III. The Biodiversity of Agroforestry Systems