Transcript 2.2.21 Structure of an Ecosystem ppt

2.2.2.1 Structure of an
Ecosystem
Ecosystems
• a community of
interdependent organisms
and the physical
environment they inhabit.
Ecology
• the study of the interrelationships of organisms
with each other and the
environment..
Ecosystem Components
2 parts
– Abiotic – nonliving components
(water, air, nutrients, solar energy)
– Biotic – living components
(plants, animals, microorganisms)
Biota
Terrestrial Ecosystems
Aquatic Life Zones
• Light penetration
• Sunlight
• Water currents
• Temperature
• Dissolved nutrient
concentrations (especially N
and P)
• Precipitation
• Wind
• Latitude (distance from equator)
• Altitude (distance above sea level)
• Suspended solids
• Salinity
• Fire frequency
• Soil
Significant abiotic factors
What abiotic factors effect this
Aquatic food chain?
The abiotic influence
• Species thrive in different physical
conditions
• Population has a range of tolerance for
each factor
• Optimum level best for most individuals
• Highly tolerant species live in a variety of
habitats with widely different conditions
The Law of Tolerance: The existence, abundance and distribution of a
species in an ecosystem are determined by whether the levels of one or
more physical or chemical factors fall within the range tolerated by
that species
Lower limit
of tolerance
Few
organisms
Abundance of organisms
Few
organisms
No
organisms
Population Size
No
organisms
Upper limit
of tolerance
Zone of
Zone of
intolerance physiological stress
Low
Optimum range
Temperature
Zone of
Zone of
physiological stress intolerance
High
Abiotic factors may be Limiting
Factors
• Limiting factor – one factor that regulates
population growth more than other factors
• Too much or too little of an abiotic factor
may limit growth of a population
• Determines K, carrying capacity of an area
• Examples
– Temperature, sunlight, dissolved oxygen
(DO), nutrient availability
Terminology and Roles of Biota
• Producers (Autotrophs) – Through
photosynthesis convert radiant to chemical
energy (energy transformation)
• Consumers (Heterotrophs) – Must consume
other organisms to meet their energy needs
– Herbivores, Carnivores, Omnivores, Scavengers,
Detritivores
• Decomposers – Break down organisms into
simple organic molecules (recycling
materials)
Tropic Levels
• The terms producer, primary consumer,
secondary consumer and tertiary
consumer refer to the organisms feeding
level in a food chain or web – this is called
its TROPHIC LEVEL.
Tropic Levels
• TROPHIC LEVEL – the position that an
organism occupies in a food chain, or a
group of organisms in a community that
occupy the same position in food chains.
Food chains
• Food chain - Sequence of organisms each of which is
the source of food for the next
Food chains
• Feeding levels in the chain (Trophic levels)
–
–
–
–
–
–
First trophic level = producer
Second trophic level = consumer, herbivore
Third trophic level = consumer, carnivore
Highest trophic level = top carnivore
Arrows indicate direction of energy flow!!!
Decomposers are not included in food chains and webs
Producers
• Transform energy into a usable form
• Starting form may be light energy or
inorganic chemicals
• Turned into organic chemical energy
• This is the form that is used at other
trophic levels
Food Webs
•
Ecosystem is an energy machine and a
matter processor
1. Autotrophs: make their own food (plants
algae & photosynthetic prokaryotes)
2. Heterotrophs: directly or indirectly depend
on photosynthetic output of primary
producers
Photoautotrophs
Consumers
• Heterotrophs: get energy from organic
matter consumed
• Primary, Secondary & Tertiary consumers
• Herbivores  primary consumers, eat
plant material e.g. – termites, deer
• Carnivores  other consumer levels, eat
animal material e.g. eagles, wolves
• Omnivores  consumers eating both e.g.
bears
Figure 53.0 Lion with kill in a grassland community
Decomposition
• Decomposers obtain energy by breaking
down glucose in the absence of oxygen
• Anaerobic respiration or fermentation
• End products = methane, ethyl alcohol,
acetic acid, hydrogen sulfide
• Matter recycling  inorganic nutrients
returned to producers
Decomposition Process
Detritus feeders
Bark beetle
engraving
Long-horned
beetle holes
Carpenter
ant
galleries
Decomposers
Termite and
carpenter
ant
work
Dry rot fungus
Wood
reduced
to powder
Time progression
Mushroom
Powder broken down by decomposers
into plant nutrients in soil
Consumers or Decomposers
• Detritivores = get their energy from detritus,
nonliving organic material  remains of dead
organisms feces, fallen leaves, wood
• May link producers to consumers
– Dung beetles, earth worms
• Saprotrophs = feed on dead organic material by
secreting digestive enzymes into it and absorbing
the digested products
• Producers can reassimilate these raw materials
– Fungi (mold, mushrooms), bacteria
Figure 53.10 Examples of terrestrial and marine food chains
Local examples
Trophic Level
Producer
Primary Consumer
Seconday Consumer
Tertiary Consumer
Quarternary Consumer
6th trophic level
Aquatic system
Terrestrial habitat
Food chains
• For complexity a real ecosystem needs FOOD WEB
which shows that individuals may exist at multiple
trophic levels in a system (omnivores)
Figure 53.11 An antarctic marine food web: Identify the trophic levels
Food Webs
•
Food webs are limited by the energy flowing
through them and the matter recycling
within them