Transcript Ch. 4_pptx

Interactions within Ecosystems
• Ecosystem- is a community and its physical
and chemical environment.
• Examples of different ecosystems
• Terrestrial ecosystems
– (e.g. Prairie, grassland, forest…….)
• Aquatic ecosystems
– (e.g. Pond, lake, stream…….)
Roles in Ecosystems
• Each organism has its own place within an
ecosystem.
• Ecological niche – an organism’s role in an
ecosystem, consisting of its place in the food
web, its habitat, it’s breeding area and time of
day at which it is most active.
Roles in Ecosystems
• Each species in an ecosystem tends to have a
different niche, a different role to play. This
helps to reduce competition between species.
• E.g. Even if two species eat the same food
they are not in competition because they may:
– Live in different places
– Eat at different times
Roles in Ecosystems
• E.g. Owls and hawks feed on many of the same
organisms, but occupy distinctly different niches.
• Owls hunt down prey with in forests
• Hawk hunt down prey in grassland and open fields
• Owls are active during dusk and at night
• Hawk hunt by daylight
• Competition is further reduced because owls and hawks nest in
different areas.
Competition for Niches
• When a new species enter an ecosystem, it causes a
disturbance because it comes into competition for a
niche with one or more of the species already in the
ecosystem.
• Exotic species – species that are not native to an
ecosystem
• The introduction of new species happens naturally.
Animals are mobile and can move from one
ecosystem to another.
Introduction of Exotic species
• The introduction of new species by humans to
an ecosystem is one of the main causes of
species depletion and extinction, second only
to habitat loss.
• Problems with introducing Exotic Species:
• No natural population controls ( predators or diseases)
• Native species may not b able to compete for space,
food or reproductive sites.
• Prey organisms may not have defence mechanisms.
Introduction of Exotic species
• The actual number of introduced species that
have established themselves in Canada is well
over 300 species.
Ecosystem Case Study
Pg 88-89 all questions
Supporting Biodiversity in
Terrestrial Ecosystems
Limiting Factors
• Different ecosystems can support different
species and varying numbers of organisms.
This is due to limiting factors such as
– Soil composition
– Moisture
– Sunlight
– Oxygen
– Predators
- Humidity
- Temperature
- Nutrients
- Competitors
Taiga
• In a forest, the amount of sunlight varies from
the top of the canopy to the forest floor.
• In Taiga biomes, the mature trees are mostly
conifers like spruce and pine
• These trees can only support certain types of
birds that have tough beaks for cracking open
cones and nuts
Taiga
• Year-round, these trees block the sunlight
from reaching the forest floor
• This determines the types of plants that can
grow below the canopy
• In the Taiga, we see shade loving plants like
shrubs, mosses and ferns
• These plants then determine which primary
consumers exist in this ecosystem
– Deer and moose
Taiga
• Due to the low growth on the forest floor,
nesting animals are only successful if they are
suitably camouflaged
Deciduous Forests
• Have higher temperatures and precipitation
than Taiga
• Also have more humus
– Decaying plant and animal matter
• These conditions lead to a richer soil and
support growth of deciduous trees
Deciduous Forests
• Spring: sun can reach all the way to forest
floor
• Summer: Canopy is full, so very little sun gets
to the understorey.
– This is ok, because the understorey had the
chance to grow in the spring and is already mature
• Resulting in support for a diverse range of
organisms
Deciduous Forests
• Lots of leaf litter
– Many different insects
• Full understorey
– Moose and deer
• Leafy canopy
– Variety of birds and climbing mammals
Limiting Factors in Aquatic
Ecosystems
• Water covers more than two-thirds of our
planet.
• Ninety-seven percent of that water is
saltwater.
• The oceans to a large extent control the
weather patterns on our planet.
• Most fresh water exists as snow or ice
Limiting factors of Aquatic Ecosystems
•
Like terrestrial ecosystems, aquatic
ecosystems are limited by three abiotic
factors:
1. The chemical environment
2. Light levels
3. Temperature
Chemical environment
1. The type of water:
– Freshwater
– Saltwater
2. The amount of oxygen dissolved in the
water.
•
The amount of dissolved oxygen depends on:
» Temperature (warmer water holds less)
» Pressure (more oxygen dissolved at sea level than
mountain streams)
» And the amount of salt and other substances dissolved
in the water (more salt, less oxygen)
Chemical environment
3. Any other dissolved substance
E.g., Naturally occurring minerals, and organic pollutants.
Limiting factors of Aquatic Ecosystems
• Light and temperature in an aquatic ecosystem may
vary over the course of the year (seasonal changes),
But these factors are also affected by the depth of
the water.
• Depending on the depth of the body of water the
amount of light available, the temperature and
oxygen levels can all vary. This will have a significant
impact on what organisms you can find.
Littoral Zone
• Littoral Zone – is the area extending out from
the lakeshore to the point where you can no
longer find plants rooted.
– Most productive part of the lake.
– High amount of sunlight.
Limnetic zone
• Limnetic zone – the area of a lake or pond in
which there is open water and sufficient light
for photosynthesis to occur.
• Most common form of organism in the zone is
plankton (small autotrophic and heterotrophic
mircrooganisms.
Profundal zone
• Profundal zone – the region of a lake beneath
the limnetic zone, in which there is insufficient
light for photosynthesis to occur.
– Most of the time only source of nutrients in the
zone are dead plants and animals that fall from
the limnetic zone.
– Low oxygen due to bacteria decomposing dead
organic matter.
– No sunlight no photosynthesis.
Alberta’ Terrestrial Ecosystems
• Ecosystems are smaller regions in the
biosphere.
• Complexity of ecosystems varies, depending
not only on the organisms that live in them
but also on abiotic factors such as climate and
local geology.
•
•
Biome is a large geographical region with a
specific climate, and the plants and animals
that are adapted to that climate.
Canada has four major Biomes:
1.
2.
3.
4.
Tundra
Taiga
Temperate deciduous forest
Grassland
Limiting Factors in Terrestrial
Ecosystems
• Terrestrial ecosystems are ecosystems that are
found anywhere on Earth that is not covered
by water.
• Despite their many differences in each
terrestrial region biotic and abiotic factors are
interdependent.
• These factors can limit the size of populations
and can also determine the number of species
that survive in each ecosystem.
Limiting Factors
•
Abiotic Factors that can limit Terrestrial
ecosystems:
1.
2.
3.
4.
Soil
Available Water
Temperature
Sunlight
Soil
• The quality and amount of soil are critical
factors in determining the size and health of
the plant community and the biodiversity of
an ecosystem.
Soil
• Soil pH
– Humans have been contributing to higher levels of
acidity in many soils by burning fossil fuels.
– Burning of fossil fuels release sulphur dioxide and
nitrogen oxides into the air which fall to earth as
acid deposition.
• Acid deposition – the process by which sulphur dioxide
and nitrogen oxides in the atmosphere form acidic
compounds and fall to Earth’s surface. (Acid rain is an
example of acid deposition)
Available Water
• The amount of available water in an
ecosystem help determine the size and health
of populations and the biodiversity of an
ecosystem.
– Recall
• Surface water
• Ground water
Temperature
• Temperature affects both biotic and abiotic
factors.
• Temperature can vary significantly throughout
the year in an ecosystem.
Sunlight
• The amount of sunlight determines what
plants will grow in an ecosystem.
• In ecosystems around the equator receive
more or less the same amount of daily
sunlight.
• Regions at more southern or northern
latitudes experience changes in the amount of
sunlight during different times of the year.
Changes in Lake Ecosystems
Aquatic Ecosystems
• Aquatic ecosystems are sustained by the
dynamic equilibrium among biotic and abiotic
factors.
• When one or more of these factors changes, it
can have profound effects on the ecosystem.
Lake Ecosystems
•
There are two types of lakes:
1. Oligotrophic
– Lakes are typically deep and cold.
– Nutrient levels are low limiting size of producer
populations.
– Limited numbers of only a few kinds of organisms.
– Water usually very clear.
Lake Ecosystems
2. Eutrophic
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–
–
–
Lakes are generally shallow and warmer.
Very good supply of nutrients.
Many species of photosynthetic organisms.
Water is often murky.
Eutrophication
• In general oligotrophic lakes gradually become
eutrophic over time and eventually filling in
and becoming dry land.
• This process is call eutrophication.
Eutrophication
Eutrophication
Eutrophication
Eutrophication
• Human sometimes accelerate eutrophication
by adding nutrients to lakes:
•
•
•
•
Human wastes
Fertilizers
Eutrophication
Household and Industrial products
Thermal energy
Water Pollution
•
•
Water pollution is any physical or chemical
change in surface water or ground water
that can harm living things.
Water pollution can be grouped into five
categories.
1.
2.
3.
4.
5.
Organic solid waste
Disease-causing organisms
Inorganic solids and dissolved minerals
Thermal energy
Organic chemicals
Eutrophication
Water Quality
• Bacteria
– Presence of coliform bacteria indicates that fecal matter is
in water (and therefore more dangerous bacteria)
• Dissolved Oxygen
– Fewer pollutants means more dissolved oxygen
• Biological Oxygen Demand
– Amount of oxygen needed by decomposers to break down
organic matter
– Indicates amount of organic matter in water (too much and
no oxygen is left for fish to breathe)