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Ecology Notes
Ecology - is the study of interactions between organisms (biotic factors) and their
nonliving environment (abiotic factors)
Biotic factors – (living factors) includes plants, animals, fungi, & microorganisms. They may be
producers, consumers, or decomposers.
Abiotic factors – (non-living factors) include climate, soil, temperature, water, air, sunlight,
humidity, pH, and atmospheric gases.
Habitat - is the place a plant or animal lives
Niche - is its total way of life or the status of an organism within its environment and
community
Life is organized into levels:
1.
2.
3.
4.
5.
6.
Organism any single living thing
Population members of the same species living in one place
Community- all the populations living in an area
Ecosystem- communities living in a similar habitat
Biomes- ecosystems covering wide areas with similar climates and organisms
Biosphere- all the living and nonliving things on earth
Producers (Autotrophs) - make their own food through photosynthesis or chemosynthesis.
Includes plants, algal protist and some bacteria.
Consumers (Heterotrophs) – Must ingest or absorb nutrients, can’t make their own food.
May be
Herbivores -feeds only on plants, producers or autotrophs
Primary Consumer – feeds on plants,
producers or autotrophs
Carnivores - feeds only on animals
Secondary Consumer – feeds on primary
consumers
Tertiary Consumer – feeds on secondary
consumers
Omnivores - feeds on plants and animals
Decomposers - Break down dead plants and animals
(detritus), recycle nutrients, includes fungi and bacteria
Scavengers – Organisms that feed on other dead organisms,
Sunlight - is the ultimate energy for life on earth, but only producers can get their energy
directly from the sun.
Trophic levels - are feeding levels of producers and consumers in an ecosystem.
1st. trophic level - producers that get energy directly from sunlight.
2nd trophic level - includes herbivores that feed directly on plants
3rd trophic level – includes carnivores that feed directly on primary consumers
Higher trophic levels- other carnivores that feed on each other
Food chains and food webs
Food Chains - show who eats whom in an ecosystem.
Food Webs - are made of several food chains. They are a more realistic view of an ecosystem.
Food Chains and Webs always begins with the producer absorbing energy from the sun.
Producers store energy in the chemical bonds of the food they make
Stored energy is passed to consumers when they eat producers or other consumers
Some energy is lost at each trophic level as heat when consumers “burn” food during cellular
respiration
10% of energy is passed on from organism to organism during consumption, 90% is lost.
Example;
Producer → Primary Consumer → Secondary Consumer
1000kcal
100kcal
10kcal
Both energy and nutrients must move through an ecosystem
Three main elements that must move through an ecosystem:
Water
Carbon
Nitrogen
Water or Hydrologic Cycle:
Cells are 70 to 90 % water
Water is needed for metabolic process
Water is most important for terrestrial organisms because of drying out
Steps in the water Cycle:
Evaporation
(water loss from lakes, rivers, oceans...)
Transpiration
(water loss from plant leaves)

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Condensation
(Water vapors form clouds)
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Precipitation
(Water returns to the earth as sleet, rain, snow….)
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Surface run-off
(returns water to bodies of water or ground water)
Carbon Cycle:
Consists of photosynthesis, cellular respiration, & decomposition
Begins with producers taking carbon dioxide from the air during photosynthesis
Carbon Cycle Steps:
Plant leaves take carbon dioxide from air

Plants store carbon as carbohydrates or starches (photosynthesis)

plants and animals release carbon dioxide back into the environment (cellular
respiration)

Decomposers return carbon back to environment (decomposition)
Nitrogen:
Needed by all organisms
Used to make proteins & nucleic acids (DNA & RNA)
Air made up of 80% nitrogen
Only Cyanobacteria & Rhizobium bacteria can use nitrogen directly from the air (nitrogen
fixation)
Bacteria found in the soil & on the roots of legumes (beans, peas ...)
Steps in the Nitrogen Cycle:
Cyanobacteria & Rhizobium take nitrogen from air
(nitrogen fixation)

Converts nitrogen gas to ammonia

Nitrifying bacteria is soil change ammonia to nitrates

plants can absorb and use nitrates to make proteins

Consumers eat plants and get proteins containing nitrogen

Decomposers break down dead organisms and return nitrogen to the air (ammonification)

Anaerobic bacteria in soil release nitrogen from nitrates into the air (denitrification)
Three main types of ecosystems:
Terrestrial (land)
Freshwater (rivers, ponds, lakes ...)
Marine (oceans & seas)
Terrestrial ecosystems are divided into 7 biomes with similar climates &
organisms
Seven Terrestrial Biomes:
Tropical Rain Forest (jungle)
Savanna (tropical grasslands)
Deserts
Grasslands
Deciduous Forest
Taiga (coniferous forest)
Tundra
Tundra
Cold and dark most of the year
Includes the artic
Permafrost is the top layer of soil that thaws and in which plants grow
No trees, but sedges and grass, mosses, and lichens
Many migratory animals
 Approximately 20 cm annual rainfall
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Taiga:
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Coniferous forest
Extends across northern Eurasia & North America
Contains conifers or evergreens (spruce, cedar, fir, pine ...)
Needle like leaves withstand weight of snow
Bear, deer, moose, wolves, mountain lions ...
Sequoia or redwood (largest conifer) grows here
Bristle cone pine oldest living conifer found here
Temperate Deciduous Forest:
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South of taiga in North America, eastern Asia, & Europe
High annual rainfall (75-150 cm)
Moderate temperatures
Well-defined seasons of about equal length
Trees loose leaves in winter (deciduous)
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Show stratification (plant layers):
1. Canopy - broad leaf deciduous trees forming uppermost layer
2. Under story - shrubs
3. Forest Floor - herbaceous plants
Songbirds, deer, rabbits, foxes, squirrels, frogs 7 toads, lizards ...
Tropical Rain forest:
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Near equator
Warm climate (20 -25 degrees C)
Plentiful rainfall (190 cm/year)
Contains the greatest diversity of plants & animals
Insects, monkeys & apes, snakes, tropical birds, leopards...
Animals & plants brightly colored
Poor soil for agriculture
Grasslands:
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Mostly grasses with a few trees due to less rainfall
Moderate climates
Good for agricultural crops
Grazing & burrowing animals dominate
Also called prairies
Savanna:
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Tropical grasslands
Warm climate & rainy season
Antelope, zebra, lions, wildebeests, hyenas, elephants...
Suffer from floods & drought
Deserts:
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Low annual rainfall
Subject to strong winds
Days usually hot & nights cold
Sahara desert is without vegetation
Succulents such as cacti & other water storing plants
Most animals nocturnal
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Lizards, snakes, roadrunners, insects, tarantula, hawks, rodents,
coyotes...
Aquatic Biomes:
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May be freshwater or saltwater
Wetlands near oceans have brackish water (mixture of fresh & salt waters)
Part of the part water or hydrologic cycle
Often polluted by man's activities
Lakes & Rivers:
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Freshwater
Oligotrophic lakes are nutrient poor (catfish, carp...)
Eutrophic lake are nutrient rich (trout, bass...)
Deep lakes have layers or strata where different plants & animals live
Phototropic organisms in upper layers for light
Estuary at mouth of river contains brackish water
Ocean Zones:
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Intertidal zone
1. Along shoreline
2. Wave action
3. Lots of light so many producers
4. Starfish, sand dollars...
Neritic Zone
1. Ocean water above continental shelf
2. Coral reef found here
3. Surrounds continents & receives light in upper layers
Oceanic Zone
1. Beyond continental shelf
2. Deepest area (up to 7 miles)
3. Bottom doesn't receive light so animals adapted to darkness (many
produce their own light, feed on other animals...)
4. Deepest area called abyss
5. Upper area gets light & called the photic zone (lots of seaweed here)
6. Floaters called plankton (microscopic organisms)
7. Swimmers such as fish called nekton
8. Bottom dwellers called benthos