completely dependent on the existence of large areas of undisturbed forest.
Land conversion as carried out by agricultural settlers or cattle ranchers in
many modern agricultural frontiers is characterized by greater degrees of per-
manence, although similarities to traditional systems may be found even
though modern colonizers may lack the knowledge of traditional shifting cul-
tivators. However, forest lands converted to other use in the latter context are
20–50 times greater in area than those affected by itinerant slash-and-burn
agriculture.
Well-established among the major agricultural functions of the fallow
period are soil fertility recovery and pest and weed control. Most biophysical
research on fallows has focused on these ecological functions (reviewed by Nye
and Greenland 1960 and Whitmore 1989), although weeds established dur-
ing the cropping period have also been shown to contribute to the reduction
of nutrient losses (Lambert and Arnason 1989). The fact that, by definition,
fallows are to be reconverted to cropland may have contributed to a lack of
interest in fallows as systems for the study of forest succession or as potential
routes for the restoration of tropical forest and the goods and services it pro-
vides, among which, of course, is biodiversity conservation. This lack of inter-
est is illustrated by recent collections of papers on the restoration of tropical
forests, which focus either on the “catalytic” role of forest plantations in the
process or on forest restoration through natural succession on pastures (see
Parrotta and Turnbull 1997 and Aide 2000, for example). Smith et al. (2001)
provide one exception to this latter trend (others are reviewed later in this
chapter). However, they emphasize that the development of land use options
for increasing forest cover in heavily deforested tropical regions faces a major
challenge in the need to combine conservation biological desirability and tech-
nical solvency with the interest of farmers.
In this chapter we seek to answer the following questions linked to the role
of shifting cultivation systems, and the landscapes they create, in biodiversity
generation and maintenance:
- What are the spatial characteristics of shifting cultivation landscapes, how
do they change over time, and what are the relationships between landscape
spatial characteristics and local and landscape biodiversity at the species
level? - What are the principal regeneration mechanisms operating in fallow vegeta-
tion, and what are their implications for plant biodiversity?
•How do the richness, diversity, and composition of individual floral and fau-
nal communities change over the shifting cultivation cycle, and what are the
mechanisms of these changes?
•Do such landscapes contribute to the conservation of organisms character-
istic of the original forests of those landscapes, either because those organ-
isms are members of the communities of the shifting agriculture mosaic,
- The Biodiversity and Conservation Potential of Shifting Cultivation Landscapes 155