Sustainability and Changing Paradigms
Sustainability and Changing ParadigmsLesson Outcomesdefine
sustainability define paradigm describe an example to illustrate a
paradigm shift examine the attitudes and practices of our
forefathers in terms of the taking of natural resources in relation
to the concept of sustainability discuss how attitudes toward our
forests have changed with respect to commercial usage, residential
usage, and replanting programs discuss the conditions necessary for
a sustainable fishery
The way that humans view the world is known as a
paradigm.Changes in paradigms are known as paradigm shifts.
SustainabilityThe modern paradigm views the Earth as a
sustainable system provided that renewable resources are not used
at a faster rate than they are replaced or recycled. The term
sustainability means that the system can meet the needs not only of
our present human population, but also those of the future.
Questions to think aboutHow would you describe your own views
about the taking of natural resources? Can man continue to exploit
the Earth's resources as if they were unlimited? Has the overall
focus shifted to environmental issues and concerns? Why are we
shifting to a different paradigm? How does loss of habitat (habitat
destruction) affect biodiversity? What responsibility do we have
regarding the extinction or endangerment of species? What
responsibility must we take regarding pollution - water, air, and
soil? How does the practice of clear-cut logging affect the
environment? Is clear-cutting of forests a sustainable practice? We
place value on products made as a result of the taking of natural
resources but do we consider the value of the original resource and
the long term cost of its destruction? Do we care about the
problems listed above? What can we do as individuals to change?
Not that long ago (early 1900s), most people believed that
natural resources were limitless.Renewable resources are those
resources that will continue to get replaced if not overused or
abused, and that are in such supply that they will last for an
extremely long time.Examples: fishery, forest, wildlife, water,
solar energy and wind.
Nonrenewable resourcesNonrenewable resources are those that are
in limited supply and can be completely used up of action is not
taken to protect them.Examples: fossil fuels (oil and gas),
minerals and soils.
Explain why each of the following is or is not a sustainable
Taking oil from the grand banks of Newfoundland. Establishing an
open pit diamond mine in the far north (tundra). Replanting trees
in a forest clear-cut. Catching more fish each year than are
Changes in our paradigms about our forest.
If trees were cut down to build a ship, a home, or to use as
fuel, little or no thought was given to it. The forest would simply
grow new trees to replace those taken. The early foresters used
simple tools including an axe and a saw. A typical forest worker
could cut and stack about two cords (a cord is defined as a pile of
wood 4 feet high x 4 feet wide x 8 feet long) of wood per day.
Todays Forestry IndustryTechnology has changed and the equipment
is available which can cut 2 cords of wood in just a few minutes
rather than a day. With this change in technology, can our forests
now be considered limitless? What will happen to our forests if we
cut them down at a rate faster than they can grow back? What effect
does clear-cutting have on the forest ecosystem?
Changes in our Paradigms about our fishery Fish would be taken
from the seas with no thought about the number that remained. It
was believed that man could never take all the fish that existed
within the lakes and oceans because there were so many fish and
relatively so few fisherman. The technology used by the inshore
fisherman included the use of an open boat known as a dory and a
single jigger attached to a length of line. The jigger would then
be brought up just off the bottom and jigged up and down until it
struck a cod. This cycle was repeated until the boat was full.
TodayModern technology has changed to include the use of factory
ships which make use of drift nets more than 5 km long, and
electronic equipment designed to detect the location of the fish.
Fish are caught by the metric ton rather than as individual fish.
The number of fish taken as a result of the use of modern
technology has destroyed the fish stocks to the point that the
Atlantic Canada fishery has been shut down to allow the recovery of
the fish stocks. Was the change in fishing technology sustainable?
Can we manage a sustainable fishery in the future?
Introduction to Ecology
Lesson outcomesdefine ecology and ecosystem distinguish between
biotic factors and abiotic factors and describe examples to
illustrate each explain how abiotic factors affect the
sustainability of the ecosystem describe examples to illustrate
biotic interactions describe ways that organisms respond to changes
in environmental conditions describe symbiotic relationships
including: mutualism, commensalism, parasitism, and predation
describe trophic structure in terms of food chains and food webs
explain how biotic and abiotic factors affect ecological
interactions and the distribution of organisms
Ecology is the scientific study of the interactions of organisms
and their environment. Interactions of organisms and their
environment refers to the way the organism affects the environment
as well as how the environment affects the organism.
An Ecosystem is a community of organisms and the physical
environment in which it lives.
Each of the following concepts describes the organisms within
their environment Abiotic Factors Biotic Factors Symbiotic
Relationships Trophic Structure Herbivore, Carnivore, Omnivore and
Abiotic factors are the nonliving factors which affect life in
any ecosystem. Some abiotic factors are described
below:SpaceTemperature Oxygen SunlightWaterInorganic and Organic
Biotic factors refer to the living environment and include all
other organisms that interact with the individual both of the same
species and all other species.
Biotic factors also includes: Detritus (decomposing animals and
plants) and Disease Predator/prey interactionCompetitionSymbiotic
Symbiotic relationships Symbiotic relationships are biotic
relationships in which two different organisms live in close
association with each other to the benefit of at least one. There
are five types of symbiotic relationships including: mutualism,
commensalism, parasitism, parisitoidism. and predation.
Symbiotic relationshipsMutualism is the type of symbiosis
resulting in mutual benefit to both of the organisms in the
relationship. An example of this would be the relationship between
the algae and fungus of lichens. The fungi penetrate the roots of
the plants and make soil nitrogen available to the plant, receiving
carbohydrates in return. This allows them to live in an environment
in which neither could survive alone.
Symbiotic relationshipsCommensalism is a relationship in which
one organism benefits from the relationship but the other organism
seems to neither be harmed nor benefited. One example to illustrate
commensalism is the beaver and the fish. A beaver builds a dam to
regulate water level which helps the beaver survive winter. The
fish benefit from the beaver, but the beaver is neither harmed nor
gains benefit from the fish. Another example of commensalism is the
relationship between trees and nesting birds.
Symbiotic relationshipsParasitism is a symbiotic relationship in
which one organism benefits and the other is harmed. The organism
that benefits is called the parasite, the organism that is harmed
is called the host. An example would be the tapeworm. They live in
the digestive tracts of various organisms, while there they are
provided with nutrient and an environment in which to grow and
reproduce. However, the host is harmed by the presence of the
Symbiotic relationshipsPredation is where the interaction is
beneficial to one species and detrimental to the other. This is not
always considered a symbiotic relationship, although it is quite
similar to parasitism, except for the degree of harm to the host or
prey. With predation, the prey is killed. An example of predation
is when a lion kills a zebra and eats it as its source of food.
Trophic StructureTrophic structure refers to the feeding
relationships within the ecosystem. These feeding relationships are
generally divided into five trophic levels based on their source of
Trophic StructureFive trophic levels based on their source of
nutrition primary producersprimary consumerssecondary consumers
tertiary consumersdecomposers (also known as detritivores).
Trophic Structure Feeding relationships are generally viewed as
a food web consisting of all the possible food chains that exist
within the ecosystem.
Trophic StructureProducers or autotrophs are organisms, such as
green plants, that produce their own food. They make organic
compounds (food such as sugar) from inorganic compounds (carbon
dioxide and water) by photosynthesis.Consumers or heterotrophs are
organisms that obtain nutrients from other organisms. They cannot
synthesize their own food so they must obtain it ready made.
Trophic StructureDecomposers are organisms of decay. These are
also called saprobes. They are generally fungi or bacteria that
break down the complex compounds in the remains of dead animals and
plants, producing simple substances that can be used again by the
Trophic StructureHerbivores are animals that feed only on
plants. Rabbits, cattle, horses, sheep and deer are all herbivores.
Carnivores are animals that feed on other animals. Some carnivores
may be predators (such as lions, hawks, and wolves who attack and
kill their prey and feed on their bodies) and some may be
scavengers (they feed on dead animals that they find). Omnivores
are animals that feed on both plants and animals. Examples of
omnivores are humans and bears. Saprobes are organisms that get
nutrients by breaking down the remains of dead plants and animals,
or their wastes. Examples of saprobes are bacteria and fungi.
1. Which branch of biology studies the interactions among
organisms and their environment? a. meteorology b. ecology c.
botany d. genetics
2. Which is an example of a biotic factor that affects the size
of a population in a specific ecosystem?a. average temperature b.
amount and kinds of soil minerals c. concentration of oxygen d.
number and kinds of predators
3. Which is the best example of a biotic interaction?a. Plants
grow more slowly in winter than in summer. b. Fish move to deeper,
cooler water during summer. c. Sea birds often compete for nesting
space. d. Wind often causes trees to grow very short.
4. Fish often live in a beaver pond. What relationship is
illustrated by this example? a. mutualism b. commensalism c.
parasitism d. predation
5. Which term refers to an animal, such as a bear, that eats
both plant and animal? a. autotroph b. primary consumer c.
herbivore d. omnivore
6. Which is required by any terrestrial ecosystem? a. a producer
b. a tertiary consumer c. at least five trophic levels d. a fourth
1. Which branch of biology studies the interactions among
organisms and their environment? a. meteorology b. ecology c.
botany d. genetics2. Which is an example of a biotic factor that
affects the size of a population in a specific ecosystem?a. average
temperature b. amount and kinds of soil minerals c. concentration
of oxygen d. number and kinds of predators3. Which is the best
example of a biotic interaction?a. Plants grow more slowly in
winter than in summer. b. Fish move to deeper, cooler water during
summer. c. Sea birds often compete for nesting space. d. Wind often
causes trees to grow very short.4. Fish often live in a beaver
pond. What relationship is illustrated by this example? a.
mutualism b. commensalism c. parasitism d. predation5. Which term
refers to an animal, such as a bear, that eats both plant and
animal? a. autotroph b. primary consumer c. herbivore d. omnivore
6. Which is required by any terrestrial ecosystem? a. a producer b.
a tertiary consumer c. at least five trophic levels d. a fourth
Read 1.5 "Ecology" on pages 22-23. Answer questions 1-6 from
"Understanding Concepts" on page 23.
Energy flow through an ecosystem The vast majority of life on
Earth depends on sunlight as its source of energy. Of all the
radiant energy that reaches the earth, some of it penetrates the
earth's atmosphere to the Earth's surface, but only a small
quantity is used to drive the process of photosynthesis.
About 0.023% of the energy that reaches the Earth is used in
photosynthesis, yet this energy is sufficient to drive nearly all
life on Earth!
The actual amount of energy that reaches the surface of the
Earth is affected by the albedo effect of clouds and dust particles
in the atmosphere. Albedo is a measure of the amount of light
reflected from an object. Albedo is normally expressed as a decimal
value representing the percentage of light reflected.
For example, clouds have an average albedo about .27 so about
27% of the suns energy is normally reflected by clouds back to
space. On a clear day, more light would be able to penetrate to the
Earths surface and as a result a greater amount of photosynthesis
Photosynthesis, a biological process, uses the energy of
sunlight to manufacture sugar, which serves as the universal food
for life. Oxygen produced as a product of photosynthesis is
released into the environment
6CO2 + 6H2O + sunlight energy C6H12O6 + 6O2 where CO2 represents
carbon dioxide H2O represents water C6H12O6 represents the sugar
molecules (carbohydrate) and O2 represents oxygen As you can see
from the formula, the energy that had originally come from the
sunlight is transferred to the molecules of sugar, (C6H12O6 ),
The sugar serves as the source of energy for nearly all life on
Earth. The energy stored in the sugar is passed from the plants to
other organisms when the plants are consumed as food. This passage
of food from producer to various consumers in turn is known as a
If the community has a great deal of biodiversity, there will be
several organisms that can feed on more than one type of food
resource as a result there would be several possible food chains.
which together make up a food web. Each step in the food chain is
called a trophic level. Corn Mouse Snake Hawkenergy flow always
begins with a producer. Producers are also known as autotrophs. The
mouse, snake, and hawk are consumers.Consumers are called
heterotrophs because they can not make their own food.
The final consumers in any food chain/web are the decomposers.
Corn Mouse Snake Hawk Decomposers
To release the energy stored in the sugar, organisms carry out a
metabolic process known as cellular respiration. The process of
cellular respiration does transfer energy from the food to the
organism for carrying life processes, but also releases heat which
can not be used any further. The transfer of energy from one
trophic level to the next is never 100% efficient since each
organism must utilize some of the energy to support its own
existence. The idea that each higher trophic level has less energy
available to it is known as the pyramid of energy.
The Pyramid of Energy.Energy is not recycled. As the food is
passed through the food web, most of the energy is lost. In general
terms, about 10% of the energy stored in one trophic level (such as
producers) is actually transferred to the next trophic level (for
example the herbivores) Eventually there is so little energy
remaining in the top trophic level that no higher trophic level can
be supported. This is why there are so few if any fourth order
consumers in an ecosystem.
The figure below represents the 10% rule for energy
Pyramids of Biomass and NumberSince the amount of water present
within the tissues of different organisms varies, biologists use
the dry mass of the organism for comparison since it is believed
that dry mass more closely reflects the actual amount of "living
matter" in the organism. The dry mass is known as biomass. The
availability of energy will also affect the number of organisms and
the mass of the organisms at each trophic level. The pyramid of
biomass is a graphical representation of the total biomass of all
the members of each trophic level. Generally the pyramid of biomass
has the same shape as the pyramid of energy. In a grassland
environment, 10,000 kg of grass and other producers (dry mass)
should support about 1,000 kg (dry mass) of grasshopper and other
plant eating insects.
The pyramid of number is the third type of graphical
representation used by biologists to study ecosystems. The pyramid
of number is often similar in shape to the pyramid of energy or
biomass, but there are exceptions. Consider a single spruce tree in
a boreal forest (biomass = 100 kg) which is infested by 100,000
spruce bud worms (total biomass = 10 kg), which are in turn eaten
by 5 insect eating birds (total biomass = 1 kg). The pyramid of
biomass would appear normal (base representing 100 kg, middle piece
representing 10 kg, and a top piece representing 1 kg). The pyramid
of number for this example will not look normal. The pyramid of
number would have a very small base representing the producer (1
tree), a very large herbivore level (100,000 spruce bud worms),
followed on top by a small predator level (5 birds).
Some species in the ecosystem function as a keystone species. A
keystone species is one considered so important to the stability of
the ecosystem, that if there was a decline in that species, the
community would not be able to maintain its stability and may even
collapse. E.g: Sea Otter
*Humans no longer regard the Earth as the centre of the
universe. Humans now recognize that the Earth is a sphere rather
than flat. The Earth's resources are not in endless supply for our
plunder. We are the caretakers of this world and we must take
responsibility for its sustainability. These are all examples of
paradigm shifts. The paradigms of modern man differ from the
paradigms of our forefathers.As you complete the activities for
this lesson, consider the following questions: How is it possible
that people thought this way? What factors contributed to this
mind-set? Are there large numbers of people who still think this