Chapter 15 Human Ecology • MHR 521Canadians in Biology
Landscape Ecologist
Deer mice (Peromyscus maniculatus) are small, mainly rural
rodents. Although they look innocuous, some deer mice
carry hantavirus, which can cause respiratory illness and
even death in humans who inhale airborne particles from
the urine or droppings of infected deer mice. Humans are
generally exposed to the virus when clearing or disturbing
areas where deer mouse droppings have accumulated.
Dr. Lenore Fahrig and three colleagues did a cross-
Canada study to determine how landscape structures
influence the movement of deer mice.Dr. Lenore FahrigThey found that certain landscape variables can
significantly affect virus incidence in deer mice. In
descending order, the most important variables were:
the presence of buildings (such as barns and granaries);
amount of deer mouse habitat in the landscape
surrounding a site; and fragmentation of the habitat
(how broken up the patches of habitat were). Of lesser
importance were variables such as temperature and
seasonal change.A professor of ecology at Carleton University, Dr. Fahrig
specializes in the relatively new field of landscape
ecology. “Landscape ecology,” she explains, “is the study
of how landscape structure affects the abundance and
distribution of organisms.” Traditional ecology has
concentrated on variables such as availability of food
and density of predators. Landscape ecology also
investigates an area’s spatial patterns and their effects
on movement, reproduction, and mortality.
“The impact of landscape structure has been ignored,
mostly because of the perceived difficulty of conducting
such large-scale studies,” says Dr. Fahrig. “This
constraint is disappearing with the increasing availability
of remotely sensed data, allowing much easier
measurement of landscape structural variables.”
Dr. Fahrig points out that “landscape structure is currently
determined largely by human activities, such as forestry,
agriculture, and development.” Since this is the case,
the results of landscape studies are relevant to land-use
decisions. For example, Dr. Fahrig has studied
deforestation and fragmentation of native Chilean forests,
recommending more sustainable regional management to
prevent the loss of species.
In a Canadian study, Dr. Fahrig and some colleagues
investigated the effects of traffic volume on traffic-related
deaths of amphibian species, such as leopard and green
frogs. Dr. Fahrig is particularly interested in the effects of
roads on distribution and persistence of populations,
which species are most vulnerable to roads, and which
road patterns are least damaging to wildlife populations.
Dr. Fahrig received her M.Sc. from Carleton University
and her Ph.D. from the University of Toronto. She has a
special interest in encouraging young women who are
considering a career in science.These and many other activities actually lower
the carrying capacity of Earth for humans — and a
variety of other living things. Our goal in attempting
to estimate carrying capacity is to understand how
big a human population Earth can sustain. To
achieve this, it is as vital for us to consider our effect
on the planet as it is to consider its effect on us.
The two interact in determining how many of us can
survive on Earth and under what conditions we must
live. Since all of our actions have some impact, it is
impossible to provide a complete review of these
effects in a single chapter or even a single book.
The final section of this chapter briefly examines
some of the issues most commonly identified as
being vitally important if we are to ensure the
continued well-being of the human population.It is extremely difficult for demographers to estimate Earth’s
carrying capacity for humans. Several factors affecting
carrying capacity are described in the next section.
Opinions vary regarding the impact that some factors have
on Earth. Consider choosing one of these issues to analyze
in detail. Write down your own opinion about the impact of
this factor before you start your research. After completing
your research, re-evaluate your position. Has it changed?COURSE CHALLENGE