Major Tropical Wilderness Areas, which have much of their primary habitat
still intact and contain high amounts of biodiversity.
By defining conservation priority areas based on threatened and distinctive
biota, the hotspot approach evaluates specific threats in manageable land
areas. Although threats vary, ubiquitous to all hotspots are disproportionately
high human population pressures. An estimated 1 billion or more people, or
close to 20 percent of the world population, live in hotspot areas, which cover
less than 12 percent of the earth’s land surface. The human population growth
rate is 1.8 percent per year in hotspots and 1.3 percent outside hotspots.
Human demand for resources in and around hotspots may be significantly
higher than in other areas. Even in the three major tropical wilderness areas
(New Guinea and Melanesian islands, upper Amazonia, and the Congo River
basin), which support low population densities of about eight people per km^2
(including several urban areas), population growth rates are well above the
average current global growth rate of 1.3 percent per year (Cincotta et al.
2000).
A second major global conservation strategy uses a representative
approach. A descriptive example of this conservation strategy, used by World
Wildlife Fund, is the ecoregion approach. This approach seeks to focus efforts
on conserving representative areas in major ecosystem and habitat types
(Olson and Dinerstein 1998). Some areas, which have maintained isolation
for long time periods, such as oceanic islands, mountain ranges, karst, and
caves, often are reservoirs of incredible amounts of biodiversity. The evolution
of flora and fauna in these regions has created unique and rare organisms,
often found nowhere else. These areas therefore are top priorities for conser-
vation.
Landscape and Local Conservation Strategies
Smaller-scale conservation efforts often use a landscape approach to conserv-
ing biodiversity (landscape scale, which includes conservation corridors, is
defined here as tens of thousands of square kilometers). This approach is most
easily incorporated into predictive computer models and therefore is used to
predict changes or shifts of ecosystems caused by environmental and anthro-
pogenic factors such as human population increase and climate change. Land-
scapes are made up of spatially heterogeneous areas where biodiversity exists
and interacts dynamically between areas. Biodiversity on the landscape scale
consists of the composition of these areas and the dynamic interactions
between areas and landscape elements. Interactions can occur through the
flow of nutrients, water, energy, organisms, and other resources. Detailed
location-specific data collection and knowledge of the pattern of spatial inter-
actions, such as biodiversity effects, are needed to capture the dynamic nature
of landscapes. This approach can be applied anywhere without the constraint
- Biodiversity Conservation in Deforested and Fragmented Tropical Landscapes 25