Human population growth influences long-term patterns of land use
(Jolly and Torrey, 1993), which is a major force behind environmental
changes. Many studies on human population and environment have been
conducted at the aggregate level (Ehrlich and Holdren, 1971; Harrison,
1991; Thompson and Jones, 1999; Reid et al., 2000; McKee et al., 2004).
For example, biodiversity loss is often related to aggregate variables, such
as human population size and population density (Cincotta, Wisnewski,
and Engelman, 2000). While these aggregate-level studies have generated
important insights, there is an increasing recognition that focusing on aggregate
variables, like population size or population growth, is not enough,
because changes in population structure (e.g., age and arrangement of
people into different households) are also important to the understanding
of land use and environmental changes (e.g., Moran, Brondizio, and
VanWey, Chapter 5; Pichon, 1997; Entwisle et al., 1998; Geoghegan et al.,
2001; Perz, 2001; Fox et al., 2003). For example, age structure and sex
structure affect patterns of land use and environmental conditions (Liu et
al., 1999a; McCracken et al., 1999; Moran, Siqueira, and Brondizio, 2003).
Also, because the household is a basic socioeconomic unit and each household
occupies a specific land area, consumes natural resources, and produces
wastes (e.g., CO2), it is essential to understand the effects of household
dynamics on the environment (MacKellar et al., 1995; Liu et al.,
2003b; Moran et al., Chapter 5; Walsh et al., Chapter 6). Household
numbers have been increasing much faster than population size has worldwide, and this trend is most likely to continue (Liu et al., 2003b). Even in
areas with declining population size, household numbers are nevertheless
increasing substantially. While population explosion (Ehrlich and Ehrlich,
1990) appears to be ebbing, household explosion is intensifying, elevating
demands for household products and releasing more wastes, which in turn
exert tremendous impacts on the environment, such as the loss and fragmentation
of wildlife habitat.
Human impact on the environment is so widespread that it exists not
only in nonprotected common property areas (e.g., Foster, Chapter 12;
Matson et al., Chapter 10), but also in many of the world’s approximately
100,000 protected areas (accounting for approximately 12 percent of the
Earth’s land surface) (World Conservation Union and World Commission
on Protected Areas, 2003), which have been established to protect natural
resources and biodiversity (Dompka, 1996; Liu, 2001). Although protected
areas are believed to be the cornerstone of biological conservation (McNeely
and Miller, 1983) and are often perceived as the safest preserves for nature
(Armesto et al., 1998), human encroachments and threats are still very
common (Dompka, 1996; Kramer et al., 1997; Liu et al., 2001). Although
in some protected areas there are no local residents or land use has been
restricted to designated zones, numbers of local residents have been increasing
and human activities have been becoming more extensive in many
protected areas. Understanding population-environment interactions in protected
areas is critically important because such areas usually contain rich
biodiversity that is vulnerable to human disturbances. Many ecological
studies have been conducted in reserves (e.g., Schaller et al., 1985), but
relatively few of those studies have explicitly investigated human dimensions,
and even fewer studies have coupled ecological and human components
(Hansen et al., 2002).
In this chapter, we use the Wolong Nature Reserve in China for the
endangered giant panda to illustrate complex linkages among human population
structure, land use, and panda habitat. We focus on two basic types
of land use—agriculture and fuelwood collection. The former is the main
source of human subsistence (food), whereas the latter provides energy for
cooking and heating. Questions that we are particularly interested in are:
• What are the reciprocal interactions among human population
structure, land use, and panda habitat (e.g., how do changes in human
population structure influence land use and panda habitat)?
• How do human population structure, land use, and panda habitat
as well as their interrelationships respond to changes in government
policies?