the land, it is probably because they have been expelled or extirpated by
human activities (Wilkie and Finn 1990; Thomas 1991; Lahm 1993).
In conclusion, differences in diversity and composition sometimes are
found when the vertebrate assemblages observed in fallows and crop fields are
compared with those of primary forest. It is likely that up to a point, anthro-
pogenic modification of forest habitat increases the diversity of the associated
fauna at many spatial scales, as in the case of Anderson’s raptor community at
the landscape scale. Diversity increases often come about because species of
disturbed habitats enter areas after disturbance and should be considered neu-
tral from the conservation standpoint. Changes in the characteristics of verte-
brate assemblages are likely to be related to changes in habitat structure, spa-
tial and temporal patterns in the availability of food, and possibly
microclimatic variation. The type and degree of changes observed at the com-
munity level depend at least partly on the characteristics of the landscape in
which observations take place.
Managing Shifting Cultivation Landscapes for
Increased Biodiversity and Conservation Value
The patchwork of stages of the shifting cultivation cycle is the dominant sin-
gle land use in many tropical landscapes. This land use, and the way it inter-
acts with remaining areas of primary communities and other human land uses,
therefore must become a main target of biodiversity-oriented research, devel-
opment, and management in such landscapes. Likely objectives for biodiver-
sity management in a shifting cultivation mosaic might be
•To maintain in the landscape as much biodiversity (human-made and wild)
as is compatible with the satisfaction of other human needs in a sustainable
way, though not necessarily to maximize biodiversity in each patch within
the landscape
•To contribute to regional efforts to conserve forest-dependent plant and ani-
mal species
Such objectives might be integrated with planning and action for biologi-
cal conservation in a context of good land management at still larger scales
than the landscape, such as in the context of the management of buffer zones
for protected areas.
We believe that the landscape scale must be the primary management focus
for biodiversity conservation. Action at the landscape scale would be comple-
mented by management at the scale of individual patches. This is because
there does not seem to be much potential for achieving increases in the biodi-
versity conservation value of individual habitat patches in shifting cultivation
landscapes. These habitat patches are small, and most of them are subjected to
the drastic disturbances associated with the agricultural cycle; the shortening
- The Biodiversity and Conservation Potential of Shifting Cultivation Landscapes 181