CHAPTER 10
SUSTAINING TERRESTRIAL BIODIVERSITY:
THE ECOSYSTEM APPROACH
By: Brooke Sergas and Madi Ennenga
HOW HAVE HUMAN ACTIVITIES AFFECTED THE
EARTH’S BIODIVERSITY?

Humans have depleted and degraded some of the earth’s
biodiversity and these threats are expected to increase.
According to a 2002 study on the impact of the human
ecological footprint on the earth’s land, we have distributed to
some extent at least half and probably 83% of the earth’s land
surface. Most of this is the result of filling in wetlands and
converting grasslands and forests to crop fields and urban
areas. Human activities such as agriculture, industry, economic
production and consumption, and recreation cause
degradation and destruction of natural ecosystems, changes in
number and distribution of species, pollution, and alteration of
natural chemical cycles and energy flows.
HOW SHOULD FOREST RESOURCES BE USED,
MANAGED, AND SUSTAINED GLOBALLY AND
IN THE UNITED STATES?

Forests provide a number of ecological and economic
services and researchers have attempted to estimate their
total monetary value. Forests provide economic services
such as fuelwood, lumber, pulp to make paper, mining,
livestock grazing, recreation, and jobs. In order to be
sustained, the U.S. needs to support energy flow and
chemical cycling, work to reduce soil erosion, absorb and
release water, purify water and air, influence local and
regional climate, store atmospheric carbon, and provide
numerous wildlife habitats.
HOW SERIOUS IS TROPICAL DEFORESTATION,
AND HOW CAN WE HELP SUSTAIN TROPICAL
FORESTS?

Large areas of ecologically and economically important tropical
forests are being cleared and degraded at a fast rate. Tropical
forests cover about 6% of the earth’s land area. Climatic and
biological data suggest that mature tropical forests once covered
at least twice as much area as they do today. Studies indicate
that at least half of the world’s species of terrestrial plants and
animals live in tropical rain forests. Each time a tract of tropical
rain forest is cleared, several species may be lost forever. We can
prevent deforestation of tropical forests by protecting the most
diverse endangered areas, educating settlers about sustainable
agriculture and forestry, adding subsidies that encourage
unsustainable forest use, protecting forests with debt-for-nature
swaps and conservation easements, certifying sustainably grown
timber, and reducing illegal cutting.
HOW SHOULD RANGELAND RESOURCES BE
USED, MANAGED, AND SUSTAINED?

Almost half of the world’s livestock graze on natural grasslands
and managed grasslands. Grasslands provide important
services such as soil formation, erosion control, nutrient
cycling, storage of atmospheric carbon, gene pools for
crossbreeding gain crops, and maintaining biodiversity. We can
sustain rangeland productivity by controlling the number and
distribution of livestock and by restoring degraded livestock. A
widely used method for sustaining grasslands is rotational
grazing in which cattle are confined by portable fencing one
area for a short time and then moved to a new location.
WHAT PROBLEMS DO PARKS FACE, AND HOW
SHOULD WE MANAGE THEM?

Countries have established more than 1,100 national parks, but
most are threatened by human activities. Local people invade most
parks in search of wood, cropland, game animals, and other natural
products for their daily survival. Most national parks are also too
small to sustain many large-animal species and many parks suffer
from nonnative species. In order to manage parks, we should
integrate plans for managing parks and nearby federal lands, add
new parkland near threatened parks, buy private land inside parks,
locate visitor parking outside parks and use shuttle buses for
entering and touring heavily used parks, increase funds for park
maintenance and repairs, survey wildlife in parks, limit the number of
visitors to crowded parks areas, raise entry fees for visitors to use
funds for park management and maintenance, and encourage
volunteers to give visitor lectures and tours.
HOW SHOULD WE ESTABLISH, DESIGN,
PROTECT, AND MANAGE TERRESTRIAL NATURE
RESERVES?

Ecologists call for protecting more land to help sustain
biodiversity, but powerful economic and political interests
oppose doing this. The best way to protect biodiversity is to
create a world-wide network of protected areas.
Conservation biologists call for full protection of at least
20% of the earth’s land area in a global system of
biodiversity reserves that includes multiple examples of all
the earth’s biomes. We can establish and connect nature
reserves in a large eco-region.
WHAT IS WILDERNESS, AND WHY IS IT
IMPORTANT?

Wilderness is land legally set aside in a large enough area to
prevent or minimize harm from human activities. Wild places
are areas where people can experience the beauty of nature
and observe natural biological diversity. They can also enhance
the mental and physical health of visitors by allowing them to
get away from noise, stress, development, and large numbers
of people. To most biologists, the most important reasons for
protecting wilderness and other areas from exploitation and
degradation are to preserve their biodiversity as a vital part of
the earth’s natural capital and to protect them as centers for
evolution in response to mostly unpredictable changes in
environmental conditions.
WHAT IS ECOLOGICAL RESTORATION, AND WHY
IS IT IMPORTANT?

Almost every natural place on earth has been affected or
degraded to some degree by human activities. Ecological
restoration is the process of repairing damage caused by
humans to the biodiversity and dynamics of natural
ecosystems. Ecologists agree that preventing ecosystem
damage in the first place is cheaper and more effective than
any form of ecological restoration. Scientists say that
restoration should not be used as an excuse for environmental
destruction. We have been able to protect or preserve 5% of
the earth’s land from the effects of human activities. Ecological
restoration is badly needed for many of the world’s ecosystems
that we have already damaged.
WHAT CAN WE DO TO HELP SUSTAIN THE
EARTH’S TERRESTRIAL BIODIVERSITY?

In order to sustain earth’s terrestrial biodiversity, we need to
take immediate action to preserve the world’s biological hot
spots, keep intact the world’s remaining old-growth forests and
cease all logging of such forests, and complete mapping of the
world’s terrestrial and aquatic biodiversity so we know what we
can make conservation efforts more precise and cost-effective.
We can determine the world’s marine hot spots and assign
them the same priority for immediate action as for those lands,
concentrate on protecting and restoring world’s water systems,
make conservation profitable, and initiate ecological
restoration projects worldwide.
VOCABULARY



Old Growth Forests- an uncut or
regenerated forest that has not been
seriously distributed by human activities or
natural disasters for at least several
hundred years.
Second Growth Forest- a stand of trees
resulting from secondary ecological
succession. Develop after trees in an area
have been removed by human activities.
Rangelands- unfenced grasslands in
temperate and tropical climates that
supply forage or vegetation for grazing and
browsing animals.

Pastures- managed grasslands or enclosed
meadows usually planted with domesticated
forage.
- Overgrazing: occurs when too many
animals graze for too long and exceed
carrying capacity of the grassland area.
- Undergrazing: absence of grazing for long
periods can reduce the net primary
productivity (npp) of grasslands vegetation
and grass cover.
VOCABULARY



Selective cutting- intermediate-aged or
mature trees in an uneven-aged forest are
cut singly or in small groups.
- Creaming: selective cutting in which all
or most of the largest trees are removed;
leads to environmental degradation.
Tree Plantation or Tree Farm- a managed
tract with uniformly aged trees of one or
two genetically uniform species that are
harvested by clear cutting as soon as they
become commercially valuable.
Buffer Zone Concept- protecting an inner
core of a reserve by establishing two
buffer zones in which people can extract
resources in ways that are sustainable and
do not harm the inner core.



Instrumental Value- value of an organism ,
species, ecosystem, or the earth’s
biodiversity based on its usefulness to
humans.
Intrinsic Value- value of an organism,
species, ecosystems, or the earth’s
biodiversity based on existence, regardless
of whether it has any usefulness to human.
Healthy Forest Restoration Act- timber
companies are allowed to cut down
economically valuable medium sized and
large trees in 71% of the total area of
national forests in return for clearing away
smaller more fire prone trees and
underbrush.
THE END