Science 1206

Unit 1 – Sustainability of Ecosystems

Paradigms and Paradigm Shifts The way that humans view the world is

known as a paradigm. Old paradigms have been replaced by new

paradigms. Changes in paradigms are known as

paradigm shifts The paradigms of modern man differ from

the paradigms of our forefathers.

Paradigms and Paradigm Shift People once believed that the world was

flat Now people know that the Earth is

almost spherical in shape

Paradigms and Paradigm ShiftsConsider your personal

view of the world as you look at the image (from NASA) of Earth from space.

Paradigms and Paradigm Shift Humans once believe that the resources

were put here for the sole benefit of humans and were endless

The 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.

Paradigms and Paradigm Shifts The Earth is like a space ship as it revolves

around the Sun, the materials that are on it have been there since it was first created and very little is being added to it, with the exception of material arriving from outer space in the form of space dust, meteorites, or other heavenly bodies.

Paradigm and Paradigm Shifts Likewise, very little material is lost from

the planet with the exception of materials such as satellites and space ship debris

Therefore, what is here is here and that is it.

Recall that elements cannot be created nor destroyed and that everything is made of one or more elements

Earth as a System Since very little material is added or

removed from the Earth, it can be ignored Therefore, the Earth can be considered to

be a closed system The materials that make up the biosphere,

the thin layer about Earth in which all living organisms exists, are not limitless as was once believed.

Earth as a System These materials are recycled, which means

that the carbon found in your cells may have once been in a T Rex over 65 million years ago.

This is the reason why the human view of the Earth changed

Forest Paradigm Shift Years ago, if trees were cut down to build a

ship, a home, or to use as fuel, little or no thought was given to it.

Forests seem to extend beyond what the eyes could see, i.e. they seemed endless

Trees could be planted and grow, replacing the ones lost

Forest Paradigm Shift Early foresters used simple tools including

an axe and a saw A typical forester could cut and stack about

two cords of wood per day. (A cord is a pile of wood 4 ft high x 4 ft wide x 8 ft long)

Today, technology has changed and the equipment now can cut 2 cords of wood in just a few minutes!

Forest Paradigm Shift With the 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?

Fishery Paradigm Shift Fish used to 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.

Fishery Paradigm Shift Initially fishermen used an open boat and a

single jigger, and they would stop when the small boat was filled

Today, technology such as nets that can be up to 5 km long, electronic equipment designed to locate fish, and freezers located on the ships can allow fishermen to catch tonnes of over a period of days.

Forest Paradigm Shift Was the change in fishing technology

sustainable? Can we manage a sustainable fishery in the

future?

Sustainability The modern paradigm views the Earth as a

sustainable system provided that renewable resources are not used faster than they are replaced or recycled.

Sustainability means that the system can meet the needs not only of our present human population, but also those of the future.

Questions to Consider1. How would you describe your own views

about the taking of natural resources?

2. Can man continue to exploit the Earth's resources as if they were unlimited?

3. Why are we shifting to a different paradigm?

Questions to Consider4. How did our fishery collapse? What

could we as people, caretakers of the Earth, done to prevent the decline in the cod stocks?

EcologyDef’n: ecology – the scientific study of the

interactions of organisms and their environment.↳ Ecology involves observations and

experiments to test hypothetical explanations of ecological phenomena.↳ Interactions of organisms and their environment refers to the way the organism affects the environment as well as how the environment affects the organism.

Ecology Ecology is a multidisciplinary field of

study involving all areas of biology as well as the physical sciences.

EcosystemsDef’n: ecosystem – a community of

organisms and the physical environment in which it lives.

Each of the following describes the organisms within their environment and their interactions with other organisms in their environment.

Abiotic FactorsDef’n: abiotic factors – the nonliving factors

which affect life in any ecosystem. These include, but are not limited to, the following:1. Space – All organisms require enough space

to insure adequate resources to food, water, shelter, and mates.

Abiotic Factors2. Temperature – Environmental temperatures

affect biological processes and the ability of most organisms to regulate their temperatures. Most organism have a temperature range in which they best function. Few organisms have an active metabolism at temperatures below 0°C or above 45°C.

Abiotic Factors3. Oxygen – Most living things require oxygen for

cellular respiration, which is the process that releases energy from food. Terrestrial organisms obtain oxygen from the atmosphere while aquatic organisms get it from the dissolved oxygen in the water.

Abiotic Factors4. Sunlight – Sunlight is the ultimate source of

energy for all photosynthetic organisms which in turn provide the resources for other living things (in most ecosystems).

5. Water – Water is necessary for all life. The ability to find water, to maintain water balance, and to conserve water help determine the habitat range for each species.

Abiotic Factors6. Inorganic and Organic Soil Nutrients –

Inorganic soil nutrients include minerals such as phosphates, nitrates, potassium, etc. derived from rocks. Organic nutrients include organic compounds in humus which promote the growth of bacteria, fungi, etc. The physical structure, water holding potential, pH, and nutrient level of soil limit the distribution of plants and in turn animals in a given area.

Biotic FactorsDef’n: biotic factors – the living environment

and include all other organisms that interact with the individual both of the same species and all other species.

Biotic factors include, but are not limited to:

1. Detritus – The decomposing plant and animal materials including their carcases as well as their wastes. Bacteria and fungi break these materials down so that other organisms can use it.

Biotic Factors2. Disease – The result of infection by fungi,

bacteria, virus, and other pathogens. Disease is an important biotic factor because disease tends to reduce the number of organisms within the community.

Biotic Factors3. Predator/Prey interaction – This also helps

reduce the size of populations within an ecosystem. A predator is an animal that kills and eats another animal for food. The prey is hunted animal. For example, a coyote kills and eats hares, therefore, the coyote is the predator and the hare is the prey.

Biotic Factors4. Competition – This is the struggle for

survival that occurs between two organism either of the same or different species. Competition tends to limit the size of the population keeping it in balance with the available resources.

Symbiotic RelationshipsDef’n: symbiotic relationships – 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:

Symbiotic RelationshipsDef’n: mutualism – the type of symbiosis

resulting in mutual benefit to both of the organisms in the relationship. For example, algae and fungus of lichens.

Symbiotic RelationshipsDef’n: commensalism – a relationship in which one organism benefits from the relationship but the other organism seems to neither be harmed nor benefited. For example, beaver and fish.

Symbiotic RelationshipsDef’n: parasitism – 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. For example, tapeworm and humans.

Symbiotic RelationshipsDef’n: parisitoidism – similar to parasitism.

One organism benefits but the other is eventually killed – a sort of slow death. For example, a female wasp stings a spider causing paralysis but not death. The wasp then lays a single egg on the spider. When the egg hatches into a larva, it slowly eats the body of the spider eventually killing it – but slowly.

Symbiotic Relationship

Symbiotic RelationshipsDef’n: predation – where the

interaction is beneficial to one species and detrimental to the other. It this case the prey is usually killed fairly quickly. For example, rabbit and coyotes.

Trophic Structure Refers to the feeding relationship within

the ecosystem Generally divided into five trophic levels

1. Primary Producers

2. Primary Consumers

3. Secondary Consumers

4. Tertiary Consumers

5. Decomposers

Feeding relationships are generally viewed as a food web consisting of all the possible food chains that exist within the ecosystem.

Producers An organism, such as a plant, that is able to

produce its own food from inorganic substances.

Producers Not all plants are producers, i.e. not all

plants produce their own food but get their food from other sources.

Pitcher Plant

Consumers Any organism that obtain nutrients from

other organism.

Autotrophs Any organism that

produces its own food. Most of these are plants but not all plants are autotrophs, for example, the pitcher plant.

Heterotrophs Any organism that needs to eat organic

material in order to obtain the nutrients it needs.

There are some organisms that can be both an autotroph and a heterotroph, depending on the environment.

Decomposers

Any organism that breaks down organic material to its simplest form (i.e. elements and compounds – molecules)

Herbivore (Primary Consumer)

Any organism that only ingests plant material in order to gain the nutrients it needs to survive.

Carnivore (Secondary Consumer) Any organism that

ingests flesh in order to gain the nutrients it needs to survive

Carnivores (Tertiary Consumer) A consumer that eats

other carnivores. The shark is considered a top carnivore because there are no carnivores that feed on it.

Omnivores Any organism that

ingests both plant material and flesh in order to gain the nutrients that they need to survive.

Decomposer/Saprobe Any organism that

ingests dead organic material in order to gain the nutrients it needs to survive.

These are very important because they recycle materials within the ecosystem

Energy Flow The initial source of all energy on Earth is

the Sun This energy can be used to evaporate

water, to heat the Earth, to provide light to the Earth, or it can be used by plants to produce food and oxygen in the process of photosynthesis.

Not all the energy radiated from the Sun reaches the Earth’s surface.

Energy Flow 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 – a measure of the amount of light reflected from an object. Usually expressed as a decimal value representing the percentage of light reflected

Energy Flow Of the energy incoming from the Sun

30% is reflected by clouds or the Earth’s surface

44% heats the atmosphere and Earth’s surface 25% heats and evaporates water 1% generates wind 0.023% is used for photosynthesis

So not much of the incoming energy is transferred though the food webs of an ecosystem

Energy FlowWhat would happen if the Sun burned out?

What would happen if plants couldn’t use solar energy anymore?

Energy Flow All living things are connected, therefore,

we all need the Sun’s energy, either directly or indirectly

Plants need the Sun’s energy directly whereas anything that eats plants or eats other animals need the Sun’s energy indirectly. Why?

Energy Flow Energy cannot be created or destroyed, but

can be converted to other forms. For example, when an animal eats a plant,

some of the energy it gets is converted to heat and is “lost” to the environment.

Therefore, the further up the food chain you go the less energy from the original plant is passed on.

Energy Pyramid This change in energy can be represented

in a pyramid. The larger parts of the pyramid have the

most energy. The energy is measured in joule (J).

Energy Pyramid

Energy Lost Why is there less energy at the top of the

pyramid? When energy is transferred some of it is lost in

the form of heat. Energy is used in metabolism (chemical

reactions in cells that provide energy for the cell)

Energy is used for all organ systems of the body such as digestion.

Energy is required in order for organism to move.

Energy Lost Since the organism at the top of the energy

pyramid are highly active they use more energy than the ones located at the base of the pyramid.

For example, a hawk needs to fly in order to capture its prey whereas a mouse only needs to travel very short distances in order to obtain food.

Pyramid of Biomass An ecosystem can also be represented by a

pyramid of biomass. Biomass is the mass of the dry matter of

organisms i.e. the mass of an organism with the water removed.

The mass is usually measured in grams (g).

Pyramid of Biomass

Pyramid of Biomass Why does the mass change as you move up

the pyramid?

How does energy availability affect the total mass of organisms in an ecosystem?

Pyramids of Biomass The availability of energy will also affect

the number of organisms and the mass of the organisms at each trophic level

Pyramids of biomass have the same shape as the pyramid of energy

Pyramids of Numbers These are usually the same shape as the

other two pyramids, but with some exceptions.

Can you think of an example?

Pyramids of Numbers

Stability To have stability means that there is a

balance between the various organisms that make up the food

Because of this balance, the ecosystem is self-sustaining over long periods of time.

Stability To be stable there must be a balance

between food production, food consumption, and decomposition of dead organisms and/or their wastes.

Therefore, there must be a source of energy (usually sunlight for photosynthesis), producers to capture the sunlight and make food, and a means to recycle the materials.

Stability The greater the biodiversity, i.e. the more

different types of organism present, in the ecosystem, the more stable it will be.

Some species in an ecosystem function as a keystone species.

Keystone Species A species that is 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.

Keystone Species Ex. Beavers – these are considered habitat

engineers because they change the environment by building dams. This dam building provides still water in which many species flourish.

Keystone Species

Succession Succession refers to the series of

ecological changes that every community undergoes over long periods of time.

Succession starts with pioneer plants and the animals associated with these plants moving into a once inhabitable area, usually one covered in rocks

Pioneer Plants

Pioneer Plants

Pioneer Plants Plants serve as food and shelter for animals Therefore, the succession in plant life

parallels that of animal life When pioneer plants and their associated

animals move into an area, a primitive community is established

Succession These plants and animals break down the

rocks into smaller and smaller pieces changing the environment

This breakdown in rocks creates soil so that larger plants can move in and with them different, larger animals

These changes keep occurring until the climax community is established

Succession The climax community is a final,

sustainable, stable, or self-perpetuating community, of dominant organisms such as large trees and large carnivores

There are many examples of succession in Newfoundland and especially Labrador

There are 2 types of succession

Primary Succession refers to a sequence beginning in an area

where there is no soil or previous forms of life

occurs in an area such as a freshly cooled lava field, or a newly formed sand dune

Very slow process on land since it begins with producing soil

Primary Succession Rocks are broken down initially by weathering,

namely rain, snow/ice, wind, etc. Then pioneer plants move in and break the rocks

down even further eventually forming soil These plants also add organic material to the soil

when they die

Primary Succession As these plants die, they build up the soil

and when the soil is thick enough, plants that require deeper soils for their roots move in and so on until trees move into the area

Once trees move, then the climax community has been reached

Primary Succession The organisms that first inhabit an area are

known as pioneer organisms.

Primary Succession

Primary Succession

Primary Succession

Primary Succession

Secondary Succession occurs in an area in which an existing

community has been partially destroyed and its balance upset, either by natural causes, such as fire, or as a result of human activity, such as the cutting of a forest, or abandoning a farm.

For example, the area burnt out in Terra Nova National Park

Secondary Succession In secondary succession, soil already exists

so pioneer plants can move in immediately Seeds already present in the soil or from

nearby communities can begin to grow soon after the disaster

The climax community can be reach sooner than in a primary succession

Secondary Succession

Secondary Succession

Secondary Succession

Secondary Succession

Factors that Contribute to Succession The type of climax community that is

established will depend on the environmental conditions of the area, including: Climate (temperature, precipitation,

availability of sunlight, etc) Soil (salinity, fertility, moisture, texture, etc.),

Factors that Contribute to Succession

geographical features (latitude, altitude, and proximity to mountain ranges or large bodies of water)

Some biologists argue that there is no such thing as a climax community because the entire earth is in constant change or upset because:

Factors that Contribute to Succession

natural (catastrophic events such as flood, fire, volcanic activity, climate change, species extinction, etc.),

and human influenced (such as acid rain, ozone depletion, enhanced global warming, pollution, habitat destruction, monoculture farming, clear-cut logging, over-fishing, etc.).

NicheDef’n: niche – the fundamental role of a species in

the community, including activities and relationships.

Describes how an organism or population responds to the distribution of resources and competitors (e. g., by growing when resources are abundant, and predators, parasites and pathogens are scarce) and how it in turn alters those same factors (e.g., limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey).

Niche No two species can occupy the same niche

in the same environment for a long time. Different species can hold similar niches in

different locations and the same species may occupy different niches in different locations.

Habitat Refers to the place where an organism

lives. Habitat is different from its niche, it is the

particular part of the environment in which it lives.

Habitat is part of an organism’s niche

Habitat The organism’s habitat is where the

organism is best adapted to survive. Plants and animals live where they can

gather or find the necessary resources to satisfy their needs.

Every habitat includes factors that limit the kinds and numbers of organisms that live there.

Habitat Sometimes, organisms can adapt

themselves to a changing habitat The organisms that associate together in a

common habitat form communities.