because that mosaic meets at least some of their needs, or because the mosaic
at least provides connectivity between remnant forest habitats?
•How might management maintain or increase the conservation value of
individual components of the landscape and of the landscape as a whole?
The Spatial Characteristics and Ecological
Dynamics of Shifting Cultivation
In the tropics, shifting cultivation landscapes characterize particular regions at
any given time and sometimes particular time periods in the development of
agricultural frontiers in any given region. Shifting cultivation is not an impor-
tant feature of all tropical agricultural frontiers (Moran et al. 1994), and some
authors (e.g., McKey 2001) assert that overall, the major phenomenon occur-
ring in modern tropical agricultural frontiers is not the implementation of
shifting cultivation systems but land conversion to uses that are intended to be
more permanent. On the other hand, shifting cultivation is not limited to
young agricultural frontiers or to remote forest areas almost devoid of inhabi-
tants. In many places in the tropics, humid or dry, it is indeed a stable land
use over time.
In the Amazon basin, extensive areas in which shifting cultivation is a prin-
cipal land use are found in the west in lowland Peru (Dourrojeanni 1987) and
in the east in Pará State, Brazil (Vieira et al. 1996, 2003). In West and Cen-
tral Africa, shifting cultivation is the norm and is part of almost all agricultural
systems, together with permanent crop fields and more sophisticated agro-
forests (de Rouw et al. 1990; Dounias 2001). Shifting cultivation is the most
widespread form of land use in the nonirrigable parts of northern Thailand
(Schmidt-Vogt 1999) and in neighboring Laos, Cambodia, and Vietnam. In
Laos, up to 1 million people may be involved in shifting cultivation, which
makes up 40 percent of the land area dedicated to the country’s principal crop,
rice, with 200,000 ha under cultivation in any given year (Fujisaka 1991;
Roder and Maniphone 1998). It is also the favored land use in less populated
regions of Indonesia, such as Kalimantan, and in the Philippines.
Fallows occupy much of the land area in swidden landscapes, and for this
and other reasons much of the potential of these landscapes for forest biodi-
versity conservation depends on them. Analyzing a 137,800-ha municipality
in eastern Pará State, Brazilian Amazon, by remote-sensing techniques, Alen-
car et al. (1994) found that around 50 percent of the total area was occupied
by fallow vegetation in three distinct developmental stages, and only 8–11
percent of the area was occupied by cropland. In contrast to the enormous area
of fallow, around 15 percent of the land was covered by residual primary for-
est, most of it in riparian strips. Vieira et al. (2003) carried out a similar study
in another Pará State municipality, finding 18, 17, and 5 percent of the
156 III. The Biodiversity of Agroforestry Systems