Download Chapter 4 Ecology

Chapter 4
Ecology
Examples of Ecosystems:
Environmental Factors Affecting Organisms
1.
Abiotic Factors
Abiotic Factors are non-living factors e.g. altitude and aspect (direction
that a surface faces).
High altitudes are colder, wetter and windier than lower altitudes.
2.
Biotic Factors
Biotic Factors are living factors. Eg. Food, competition, predation.
The more food that is available the greater the number of organisms that
will survive.
3.
Climatic Factors
Climatic Factors refer to weather over a long period of time.
E.g. temperature, rainfall etc.
Higher temperatures cause faster plant growth.
4.
Edaptic Factors
Edaptic Factors relate to soil.
e.g. Soil type, soil pH, organic matter present.
Neutral soil has a pH close to 7 and are preferred by most plants.
A grazing food chain is a sequence of organisms in which each one is eaten
by the next member in the chain.
Producers: Organisms that carry out photosynthesis.
e.g. oak tree.
Flora: All the plants in an ecosystem.
Consumers: Organisms that take in food from another
organism.
Fauna: All the animals in an ecosystem.
Decomposers: Organisms that feed on dead organic
matter.
Detritus Feeders: Organisms that feed on small pieces of
dead organic matter.
A trophic Level is a feeding stage in a food
chain.
A food web consists of two or more interlinked food chains.
Nitrogen Fixation is the conversion of nitrogen gas into
ammonia, ammonium or nitrate.
Nitrification is the conversion of ammonia and
ammonium compounds to nitrite then to nitrate.
Denitrification is the conversion of nitrates to nitrogen
gas.
The nitrogen Cycle
The function of the Nitrogen Cycle is to remove nitrogen
from the air and make it available for use by living things.
Nitrogen is needed by living things to make protein and
other bio-molecules.
Steps in the Nitrogen Cycle
1.
Nitrogen gas makes up about 79% of the atmosphere.
2.
Nitrogen fixation carried out by e.g. volcanos, lightening and some
bacteria removes nitrogen from the atmosphere.
Symbiotic bacteria are
found in the root nodules of
legumes e.g. pea plants and
they trap nitrogen from the
atmosphere.
3.
Decomposition of dead organisms
is carried out by bacteria & fungi in
the soil.
4.
Nitrification is carried out by bacteria in the soil.
5.
Some nitrates formed in the soil are used by plants for growth.
6.
Dentitrification is carried out by denitrifying bacteria in the soil.
Human Impact on Ecosystems
In a short time 200,000 years humans have had a huge effect on
the earths resources.
Three ways humans affect ecosystems:
1. Pollution
2. Conservation
3. Waste Management
Control of Ozone Depletion
1.
2.
Reduction of use of CFCs
Fridges should not be dumped in landfill sites.
Conservation is the wise management of the existing natural
resources in an ecosystem in order to maintain a wide range of
habitats and prevent the death and extinction of organisms.
Conservation is a responsibility
of everyone. It is important
To slow down and prevent
damage to ecosystems &
habitats.
Fisheries
Problems associated with fisheries:
1.
Pollution – some fish stocks e.g. cod will take years to regenerate
2.
Overfishing – has reduced fish stocks
3.
Small mesh nets – have reduced the numbers of young fish.
Conservation in Fisheries:
Size of mesh in fishing nets is very important. If the mesh size is too small very
young fish are trapped as well as older fish depleting fish stocks.
Waste Management
Modern living creates large amounts of waste material.
It is important to manage this waste material to prevent pollution.
Agriculture
Many of our inland lakes have been depleted of fish e.g. due to a
lack of oxygen in the water.
Slurry (liquefied waste material produced by animals). When slurry
enters rivers it causes increased algal growth. The addition of
nutrients to fresh water is called eutrophication. When algae die
they are broken down by bacteria and depletes the oxygen through
respiration of the bacteria.
Aquatic animals and plants die when they don’t get sufficient
oxygen.
Fisheries
Waste materials from fish e.g. heads,
blood etc. can be recycled as fertilisers
or pig feed.
Forestry
Waste products in forestry include include: tops of
trees, small branches, tree stumps etc.
Problems associated with waste disposal
Role of micro-organisms in waste management
1. Landfill sites – most waste is disposed of in landfill
sites. Bacteria & fungi in the soil break down the
organic material (biodegradable).
2. Sewage – waste from toilets, bathrooms, industry &
rainwater from drains.
Primary sewage treatment involves physically
screening or filtering waste and allowing it to settle.
Secondary sewage treatment is when waste is acted
on by bacteria & fungi. This biological treatment breaks
down most organic waste.
Tertiary sewage treatment removes mineral nutrients
e.g. phosphates & nitrates.
Control of Waste Management
1. Reduce – reduce consumption of goods
2. Reuse – re-use clothing
3. Recycle – Collect products e.g. glass and plastic and
remake into other products.