Ecology by ajizai

VIEWS: 24 PAGES: 108


Unit 2
Table of contents

 Lakes and temperature
 Disappearing frogs
 Endangered species
 Carbon cycle
 Nitrogen cycle
 Population
Water Temperature

 Easy and important measurement
 Helps scientists understand other
    – Dissolved O2
    – pH
   Determines amount and diversity of
    aquatic life
Cold Lakes

   have life only at certain times
    – Winter little plant life
    – Spring/summer
       • plants bloom
       • Nutrients from the bottom circulate to the top
       • rapid growth of microscopic plants and
         animals that are food for fish
       • ideal spawning time for fish
Water temperature is important

   Warm water can kill sensitive species
    – Trout
    – Salmon
   Since it has less O2 which they need
Water temperature and local
   Water has higher heat capacity
    – So it influences the land and air around it
 Warm water warms the air and land around it
 Cold water cools the air and land around it
 Evaporating and condensing water makes air
  more humid and leads to rain/snow
Disappearing Frogs

Section 1.1
Why should we be concerned?

 Tell us about the health of their
 2 lives
    – Eggs and tadpole in ponds
    – Adult in forest and grasslands
   Any problems in ponds, forest,
    grassland impacts frogs tells us about
    poor health of these areas
Frogs and their ecosystem

 Live 2 lives so also part of 2 different
  food chains
 Start as herbivore in pond eating algae
 Adults are carnivores eating mostly
     Food chain

        step-by-step sequence linking
         organisms that feed on each other

 An organism that uses photosynthesis
  to make their own food
 Done by plants, algae, and some

   Organism that must eat producers
    (plants, algae) or other consumers
    (animals) in order to survive

 Plant and algae eaters
 When they eat dead plant and algae
  they are called decomposers
    – Nutrients/wastes are returned to soil and

   Eat animals including insects, fish, and
    larger animals
Why are frogs disappearing?
   Loss of habitat
    – Wetlands important for breeding and egg laying
      are removed or polluted
    – Forests and grasslands important for adults are
   Air and water Quality
    – Frogs absorbed pollutants easily through their
      lungs and thin skin
    – Acid rain biggest pollution problem
    – High acid causes reproductive and growth
Why are frogs disappearing?
   UV
    – from the sun passes through the thin frog skin
      causing damage
    – Ozone layer depletion means an increase in UV
      radiation for all species
   Climate Change
    – Ponds dry up and temperatures change too
      quickly for frogs to adjust
    – Fossil fuels are the big cause to the acceleration
      of climate change
Endangered Species

Section 1.2
Section 1.2

 Covered by worksheet
 Make sure you can list each status type
  and give 1 example
Ecology Terms

Section 1.3

 Study of nature’s economy
 Study of environment including living
  things and non-living things

 An organisms surroundings
 How an organism interacts with its
  surroundings affects its growth, feeding
  habits, and reproduction.
Categories of factors that impact
   Abiotic factors                 Biotic factors
    –   Air temperature              –   Animals
    –   Type of rock                 –   Plants
    –   Sunlight                     –   Fungi
    –   All non-living things        –   All living things

All living things interact with abiotic factors
Organizing living things


   An individual organism
    – Mouse
    – Goose
    – Dandelion
    – Hawk

   A group of the same kind of individual
    – A collection of mice living in the school

   A collection of organisms living in an
    – Mice population at school
    – Fly population at school
    – Ant population at school
    – Human population at school
    – Tree population at school
    – Lawn grass population at school

 Large geographic area with similar
  climate, plants, animals
 Grassland
 Boreal forest
 Tundra
 Etc.

   All the parts of the Earth where there
    are living things

 A lot of variety in living things
 More biodiverse = less fragile
Energy in

Section 1.7
Energy from the Sun

 Major source of energy for Earth
 Evaporation of water from oceans and
 Plants use energy for photosynthesis
Flow of energy from
sun  Earth  sun
Greenhouse gases

 Gases found in atmosphere
 Reflect escaping energy back to earth
Absorbed and Reflected
   Sunlight strikes object
    – Some absorbed
    – Some reflected
    – Depends on the surface
   Measurement called
   Dark colours absorb
    – Feels hot
   Light colours reflect sun
    – Feels cold
Energy Movement in Ecosystems

   Energy is not created nor destroyed
    – It moves from one organism to another
      along different levels of a food chain
   Trophic levels: level on a food chain
     Trophic levels
   3rd trophic level:
    – Hawk
    – Wolf
   2nd trophic level:
    primary consumers
    – Mouse
    – Deer
   1st trophic level
    – producers

 1st trophic level
 Make their own food  photosynthesis
    – Use energy of sun and other nutrients
   Examples
    – Plants
    – Algae
    – Some bacteria
Primary consumers

 2nd trophic level
 Herbivores
    – Get their energy from 1st trophic level
   Examples
    – Mice
    – deer
Secondary consumer

 3rd trophic level
 Carnivores (sometimes omnivores)
    – Get energy from 2nd trophic level
    – Indirectly rely on energy from 1st trophic
Energy in Food Chains and Food
                   Every organism in an
                    ecosystem provides
                    energy for other
                   Food chains show who
                    its whom in ecosystem
                   Wolf eats deer
                   Deer eats spruce buds
Food supply in ecosystem

                 Food chain shows
                  only 1 food supply
                 Organisms usually
                  have many food
                 Food webs show
                  interconnected food
Food webs and biodiversity

   Tropical rain forest has complex food
    – Plenty to eat
    – A lot of variety in organisms
   Arctic tundra has simpler food webs
    – Less to eat
    – Not a lot of variety in organisms
    – Very delicate food web
Energy Transfer

   Not all energy in plants is transferred to
    2nd trophic level
    – Mouse eats seeds
       • Keeps warm (changed to heat energy)
       • Allows movement (changed to kinetic energy)
       • Keep body cells and organs working (heat,
       • Some energy stored as muscle, fat, bone, skin
Energy Transfer cont

   Energy used (changed to another form
    of energy) is not available for 3rd trophic
    – Fox eats mouse
       • Can only get energy from chemical energy
         stored in mouse
   Amount of energy available is reduced
    from one organism to another
Energy Transfer cont
Energy Transfer cont
Food pyramid
                Shows energy flow of
                 food chains/webs
                Shows not all energy is
                 transferred to next
                 trophic level
                Each trophic level
                 upward needs to eat
                 more individual
                Only a few animals can
                 survive at top trophic
The Carbon Cycle

Section 1.8
Classification of Matter

   Organic          Proteins
    –C               Fats
    –H               Sugars
   Inorganic
    – Not C, H
                     CO2
                     H2O
                     NH3
Cycling of Organic Matter

   Building blocks of matter
    – Atoms of our planet
   C atom in you was part of
    past living organism
    – Digested to simple sugars
    – Decay by decomposers
      after death
Decomposer - fungus
Decomposer - fungus
Decomposer - bacteria

 Plants use light
 Reactants: CO2 and
 Products: sugar and
Photosynthesis and Cellular
   Photosynthesis
    – Carbon dioxide + water  sugars + oxygen
    – Process in plants cells
   Cellular Respiration
    – Sugars + oxygen  carbon dioxide + water
    – Process in cells of all living things
   Carbon cycle: repeated cycling of C
    through both of these processes
Inorganic C Storage
Inorganic C storage

   3 main storage areas
    – Atmosphere
       • Volcanic action
       • Burning fuels (wood, coal, gasoline)
    – Oceans
       • water with CO2 large amount
    – Earth’s crust
       • Stored as limestonelargest amount
Organic C Storage

   Bodies of living things
    – Decomposition returns C to inorganic form
    – Rapid process
   Bogs stored as peat
    – Low oxygen means decomposition is slow
Human impact

   Release carbon from organic reservoir
    – Mining
    – Burning fossil fuels
    – Burning forests
   Increasing carbon dioxide in inorganic
    – Clearing vegetation
Nitrogen Cycle

Section 2.6

 Very stable gas
 Reacts under limited conditions
 Required in cells to make
    – Protein
    – DNA
 79% of Earth’s atmosphere
 Accessible to most organisms as nitrate
Converting N to       NO3-

 Process called Nitrogen fixation
 2 ways
    – Lightning
    – Soil bacteria
1. Lightning

 Energy from lightning causes N gas to
  react with O in air, producing nitrates
 Dissolves in rain soilplant
 Nitrates make up amino acids
 Amino acids important for protein
2. Bacteria and soil

 Bacteria found mostly in soil and
  sometimes in small lumps on plants
 Provide plants with a “built-in” supply of
  usable N, and plants in turn supply
  bacteria with sugar they need to make
  nitrates (symbiotic relationship)
 Excess N moves into soil and is
  available for other plants to use

 Play a role in N fixation
 Break down N-containing chemicals into
  waste such as ammonia
 Other bacteria convert ammonia into
 Nitrites converted to nitrates
 All requires O2 to function
Decomposer example

 Farmers who use manure and fertilizers
  rely on the previous processes
 When there are not enough nitrates in
  soil, plant leaves may not be green
  (more yellowish) because chlorophyll is
  a protein

 Completes N cycle
 Bacteria can convert nitrates into N gas
  (done without O2)
 This is why gardeners aerate their
Phosphorous cycle

   Key element in
    – cell membranes
    – Molecules that help release chemical
    – The making of long molecules of DNA
    – The calcium phosphate of bones
Cycles in 2 main ways

 Long-term cycles
 Short-term cycles
1. Long-term cycles

 Involves the rocks of the earth’s crust
 Phosphates eroded from rock enter
  water cycle and are absorbed by algae
  and other plants (beginning of food
 When animals die bones and shells fall
  to ocean floor covered with sediment
  and become rock
2. Short-term cycle

 Involves living organism
 Wastes from living organisms are
  broken down by decomposers which
  release the phosphates

 Nitrates and phosphates are both nutrients
  which are essential to living things
 The rate at which the nutrients are cycled is
  linked to the rate of decomposition
 Warmth, moist soil and specialized
  decomposers permit a cycle to be completed
  in a shorter period of time
Agriculture and
nutrient cycle
When crops are harvested

 Valuable nitrogen and phosphorous
  from the plants is removed and not
  returned to the field or orchard
 Soil will eventually become depleted of
  these sources unless the farmer
  replaces by fertilizing

   Are materials used to restore nutrients
    and increase production from land
Soil bacteria

 Converts N content of fertilizer to
 If too high many increase amount of
  nitric acid in soil which affects
  organisms in soil

 Most grassland soils have pH near 7
 If pH drops to 6, some sensitive crops
  don’t grow well
Near great lakes

 Soils more vulnerable to drop in pH
 pH of 5 will affect almost all commercial

Section 1.12
Human Population

   Stable 1000’s of years before
    – Stop hunter gather
    – Store food during winter and drought
   Steady rise with agriculture
    – at 500 million 1600
Human Population

   Last 3 centuries growth exponential
Population Growth Patterns

   There are 4 factors that commonly affect population
    sizes: (INCREASE        DECREASE)
   1. Natality – # of offspring born in a year
   2. Immigration – # of individuals who move into
    a population
   3. Mortality – # of individuals who die in a year
   4. Emigration – # of individuals who move out
    of a population
Population Growth
Population growth = (births + immigration) – (deaths + emigration)
Calculating populations

 Before 2007, the mice population on the
  school field was 30
 During 2007
    – 20 births
    – 15 immigrations from field under
    – 12 deaths
    – 6 emigrations to neighbour yards
Calculating populations

 Population growth = (births + immigration) –
  (deaths + emigration)
 =(20 + 15) – (12 + 6)
 = 35 – 18
 = 17
Calculating populations
What is the population at the end of the year 2007?
Current population = previous population + population growth
                   = 30 + 17
                   = 47
Types of Populations

     Open Population
    – all four factors affect the population size
    – ex. the city of Cambridge
   Closed Population
    – only mortality and natality affect population size.
    – Ex. an ocean island
    – Ex game reserve
Population Histograms

 Examine the population in terms of its
  age structure
 Double histograms involve both genders
    – Allows examination of population in terms
      of the age structure and proportion of
      males and females
    – Pyramid Shape
Wide based pyramid

 Young population
 Rapidly growing
 # births high
Stable Population pyramid

 Fewer births
 Infant mortality fairly
  high so population
  grows slowly
 Population
  approaching zero
  population growth
Narrow based pyramid

 Fewer offspring
 If trend continues
  population declines

 Mexico rapidly growing
 Sweden will soon decline
 What do you predict for Canadian
 Refer to figure 3
Figure 3
Limits on

Section 1.12 continued
Consider mouse…

 Litters of 6+
 Reproduce every 6 weeks
 6 weeks to sexual maturity
 Why hasn’t the world been covered in
Limits on all populations
Biotic potential

 Maximum number of offspring species
  could produce with unlimited resources
 Regulated by 4 factors
    – Birth potential
    – Capacity for survival
    – Procreation
    – Length of reproductive life
Factors that determine Biotic
Limiting Factors

   Factors provided by environment
    prevent populations from reaching biotic
Fern example

 50,000 spores/year
 Drier weather
  reduces population
 Grazing animals
  reduces population
 Usually several
Carrying Capacity

 Communities tend toward stability
 Achieved when ecosystem in
 None of the populations exceed
  carrying capacity
Carrying Capacity

 is maximum # of individuals of a species
  that can be supported indefinitely by an
 Determined by availability of resources
Carrying capacity

 Population can exceed for short time
 Ex mice population increases
    – All available food eaten
    – Lack of food leads to illness
    – Easier prey for owls
    – Population decreases again to or below cc
Limits of Tolerance

 Living things need certain level of
  nutrients and conditions to survive
Law of minimum: nutrient in least supply
  limits growth
Law of tolerance: organism can survive
  within a certain range of an abiotic
Law of Tolerance

   Population of fish likely increase as water temp.
    closer to optimum
   No fish survive if too hot or cold
Density Dependent and
Independent Factors
Density independent factors
 Affect members of population regardless of
 Ex. Fires and floods
Density dependent factors
 Affect population b/c of density
 Ex. Food supply, water quality, sunlight,
 Lower food supply means energy lost to
Density Dependent and
Independent Factors

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