The Natural Environment and the
Human Economy:
An Ecological Perspective
The Biosphere and Human Economy
– The following are key elements of the basic
principles governing the nature, structure
and function of the biosphere (hence,
environmental resources) and the functional
linkages (relationships) between the
biosphere and the human economy:
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 Environmental resources or the biosphere is finite.
Hence, environmental resources are scarce in
absolute terms.
• In nature, everything is related to everything else.
Moreover, survival of the biosphere requires
recognition of the mutual interdependencies
among all the elements that constitute the
biosphere
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•
At a functional level and from a purely physical viewpoint,
the biosphere is characterized by a continuous
transformation of matter and energy. Furthermore, the
transformation of matter and energy are governed by some
immutable natural laws.
• Material recycling is essential for the growth and
revitalization of all the subsystems of the biosphere,
including the human economy.
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• Granted that nothing remains constant in nature.
Furthermore, changes in ecosystems do not appear
to occur in an absolutely linear and predictable
manner. However, measured in a geological time
scale, the natural tendency of an ecological
community (species of plants, animals and
microorganisms living together) tends to be to
progress from simple and unstable relationships
(pioneer stage) to a more stable, resilient, diverse
and complex community.
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 The human economy is a subsystem of the biosphere and it
would be dangerously misleading to view natural resources
as just factors of production lying outside the confines of
the larger system.
 The natural disposition of the technological human has
tended towards the simplification of the natural systems
eventually leading toward less stable, resilient, and diverse
ecological communities.
What is Ecology?
• Ecology is a branch of science that
systematically studies the relationships
between living organisms and the physical
and chemical environment in which they
live.
Why Study Ecology?
 to provide a broader and deeper understanding of
the natural process by which natural resources
are created and maintained;
 to understand some of the natural laws that
impose limitations on the interaction of
organisms (including humans) with their living
and nonliving environment;
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• to show the specific ways in which human
interaction with nature has been incompatible,
and
 to identify some of the important links between
ecology and economics, two disciplines which
are imperative for a holistic view of natural
resource problems and issues.
ECOSYSTEM: A Starting Point of Ecological
Study
• An ecosystem includes living organisms in
a specified physical environment, the
multitude of interactions between the
organisms, and the non-biological factors in
the physical environment that limit their
growth and reproduction, such as air, water,
minerals, and temperature.
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• Major components of an ecosystem:
– Abiotic (nonliving) components
• The atmosphere (air)
• The hydrosphere (water)
• The lithosphere (earth crust)
– Biotic (living) component
• Producers -- organisms capable of photosynthesis
• Consumers -- herbivores and carnivores
• Decomposers -- microorganism
– The Biosphere = Abiotic + biotic = Life
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• Broadly viewed, the abiotic components of
an ecosystem serve as :
– Habitat (space) and immediate source of water
and oxygen to organisms.
– Reservoir of the six most essential elements for
life (C, O, H, N, S, P). These elements
constitute 95% of living organisms; and found
in fixed amount.
– An agent for “material” recycling!
Ecosystem Functions
• Ecosystem function  movement or
transformation of matter and energy.
– Requires constant flow of external energy
– Solar radiation--fuels the natural ecosystem
– The movements of matter and energy are
represented by various forms of cycles.
The Biotic Cycle
• Matter and energy flow in the biotic cycle
(see Figure --):
– The role of the producers
– The role of the consumers
– The role of the decomposers
• Material recycling at the biotic cycle level
– Material recycling is not 100% efficient
Implications
• In a natural ecosystem, living and nonliving matter has reciprocal relationships.
For that matter, survival and ‘proper’
ecosystem functioning dictate mutual
interactions (interdependence) among
organisms and between them and the abiotic
environment.
Other well known cycles
• Atmospheric Cycles -- carbon, nitrogen,
sulfur, etc.
• Geologic Cycle, recycling of phosphate
• Hydrologic cycles
• Biogeochemical cycles
Ecological Development
• Ecological succession -- involves natural
changes in the species composition (types
of plants, animals, and micro-organisms)
that occupy a given area over a period of
time, as well as the changes that occur in
ecosystem dynamics such as energy flow
and nutrient cycling.
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• Pioneer stage: populated by a few species
and simple interrelationships.
• Climax stage: stable and supports a large
number of organisms with complex and
diverse interrelationships.
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• Does increasing diversity lead to ecological
stability and resilience?
– Stability refers to the ability of a natural
ecosystem to return to its original condition
after a change or disturbance.
– Resilience of a system refers to the rate at
which a perturbed system will return to its
original state. (see next slide)
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– The conventional wisdom seem to be that as
succession proceeds there tends to be an
increase in stability, resilience, diversity, and
complexity.
– However, some ecologists argue that the more
interconnected the components of the system
are, the less stable the system is likely to have
major impacts on closely connected species,
initiating a ‘ripple effect through the system.
The Law of Matter and Energy
• Why is it that natural ecosystems need to
have a continuous flow of energy from an
external source ?
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• Definition of terms:
– Matter is defined as anything that occupies a
space and has mass
– Energy may be viewed as an entity that lack
mass but contains the capacity for moving
and/or transforming an object--capacity to do
work.
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• The First Law of Thermodynamics states
that matter and energy can neither be
created nor destroyed, only transformed.
– We can never really throw matter away.
– Or, everything must go somewhere.
– In terms of quantity the total energy/matter in
the “universe” is constant.
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• The Second Law of Thermodynamics states
that each time useful energy is converted or
transformed from one state (or form) to
another, there always is less useful energy
available in the second state than there was
in the second. (see next slide for
implications)
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• Implications of the Second Law:
– Energy varies in its quality or ability to do work.
– In all conversion of energy to work, there will
always be a certain waste or loss of energy
quality. The principle of energy degradation or
entropy is universal.
– No perfect energy conversion system--limits on
conventional energy conversion technology.
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– Energy moves unidirectionally--from high to
low temperature. By implication, we can never
recycle energy.
• This last point, clearly explains why the natural
ecosystem requires continual energy flow from
an external source.
The Basic Lessons of Ecology
• The substance that we often identify as
natural resources (air, water, food, minerals,
valleys, mountains, forests, waterfalls,
wilderness, etc.) evolved from a multitude of
complex interactions of living and non-living
organisms, that are powered by the energy
from the sun over a period measured on
geological time scale.
– Hence, natural resources are not just factors of
production
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• The interactions among the elemental
components of the biosphere are governed
by three principles:
– First, all matter in the ecosphere is mutually
linked. Hence, human economy cannot be
viewed in isolation as the Circular Diagram
model depicts it.
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– Second, material recycling is essential for the
growth and revitalization of all the components
of the ecosphere. No such thing as waste in
nature.
– Third, the various components of the biosphere
go through gradual process of developmental
stages--from pioneer to climax.
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• The biosphere cannot escape the fundamental
laws of matter and energy:
– First law:
• natural resources are finite
• pollution is an inevitable by-product of any
transformation of matter-energy (including the human
economy).
– Second law:
• energy cannot be recycled
• no perfect machine--limit on energy conversion
technology
Humanity as the Breaker of Climaxes
• Simplification of the Ecosystem:
– Monoculture and its implication--the case of the
Irish Potato Famine
• Creation of industrial pollution (waste):
– Waste beyond ecological thresholds (carbon
dioxide emission and global warming)
– Waste that are new to the natural ecosystem
• Introduction of envasive plant and animal
species
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• Introduction of evasive plant and animal
species
– The end result of all this is a decline in the
productivity and diversity of the natural
ecosystems.