Essentials of Ecology

CONCEPT 10-4 237

reserves. This means protecting an inner core of a re-

serve by usually establishing two buffer zones in which

local people can extract resources sustainably without
harming the inner core. Instead of shutting people out

of the protected areas and likely creating enemies, this
approach enlists local people as partners in protecting a

reserve from unsustainable uses such as illegal logging

and poaching.
The United Nations has used this principle in creat-

ing its global network of 529 biosphere reserves in 105
countries (Figure 10-24). According to Craig Leisher,

an economist for The Nature Conservancy, “Local peo-

ple are often the best people in developing countries to
manage these conservation areas, because they want

them to survive in the long term as well.”
So far, most biosphere reserves fall short of these

ideals and receive too little funding for their protec-

tion and management. An international fund to help
make up the shortfall would cost about $100 million

per year—about the amount spent every 90 minutes
on weapons by the world’s nations.

Establishing protected habitat corridors between
isolated reserves helps to support more species and

allows migration by vertebrates that need large

ranges. Corridors also permit migration of individu-
als and populations when environmental conditions

in a reserve deteriorate, forcing animals to move to
a new location, and they support animals that must

make seasonal migrations to obtain food. Corridors

may also enable some species to shift their ranges
if global climate change makes their current ranges

uninhabitable.

Core area

Buffer zone 1

Buffer zone 2

Core area

Buffer zone 1

Visitor

education

center

Research

station

Human

settlements

Buffer zone 2

Biosphere Reserve Figure 10-24^ Solutions:^

a model biosphere reserve.

Each reserve contains a

protected inner core sur-

rounded by two buffer

zones that local and indig-

enous people can use for

sustainable logging, grow-

ing limited crops, grazing

cattle, hunting, fishing, and

ecotourism. Question: Do

you think some of these

reserves should be free of

all human activity, including

ecotourism? Why or why

not?

On the other hand, corridors can threaten isolated

populations by allowing movement of pest species, dis-

ease, fire, and invasive species between reserves. They

also increase exposure of migrating species to natural

predators, human hunters, and pollution. In addition,

corridors can be costly to acquire, protect, and manage.

Nevertheless, an extensive study, reported in 2006,

showed that areas connected by corridors host a greater

variety of birds, insects, small mammals, and plant spe-

cies. And in that study, nonnative species did not in-

vade the connected areas.

The creation of large reserves connected by corridors

on an eco-regional scale is the grand goal of many con-

servation biologists. This idea is being put into practice in

places such as Costa Rica (see the following Case Study).

RESEARCH FRONTIER

Learning how to design, locate, connect, and manage net-

works of effective nature preserves. See academic.cengage

.com/biology/miller.

■ CASE STUDY

Costa Rica—A Global

Conservation Leader

Tropical forests once completely covered Central Amer-

ica’s Costa Rica, which is smaller in area than the U.S.

state of West Virginia and about one-tenth the size of

France. Between 1963 and 1983, politically powerful