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ECOLOGY NOTES - CHAPTERS 3
THE BIOSPHERE
I.
Ecology
A.
Comes from the Greek language
B.
Oikos means “home” or “place to live;” logy means “the study of”
C.
Ecology – the study of the home in which organisms live.
D.
It studies the relationships of living things to each other and to their environment.
E.
Biotic - living factors
F.
Abiotic - non-living factors
II.
Levels of Organization (smallest to largest)
A.
Species – group of organisms that can interbreed and produce fertile offspring
B.
Population - group of the same species that live in a given area
C.
Community – different populations that live together in a defined area
D.
Ecosystem - all the biotic and abiotic factors in a given place
E.
Biome – group of ecosystems that have same climate and dominant communities
III.
Energy Flow in Ecosystems
A.
An organism cannot survive without a supply of energy.
B.
Ways of Obtaining Energy
1.
Autotroph (Producer) an organism that makes its own food a.
Sunlight is the main energy source for life on Earth. Capture energy from sunlight
(plants, algae and bacteria such as cyanobacteria)
Photosynthesis:
 green leaves absorb energy from the sun and convert it to carbohydrates.
 uses chlorophyll to do this b.
Some types of organisms rely on the energy stored in inorganic chemical compounds.
Capture chemical energy (bacteria living in volcanic vents on the deep ocean floor)
Chemosynthesis:
 organisms use chemical energy to produce carbohydrates.
 bacteria have evolved to use the hydrogen sulfide (Archaebacteria)
2.
Heterotroph (Consumer) an organism that gets its energy by eating other organisms , relies on others for food
IV.
Who Eats What?
A.
Herbivores - eat plants; consume producers
B.
Carnivores - flesh eaters; eat other consumers
C.
Omnivores - eats both plants and meat; eat producers and consumers
D.
Decomposers – break down dead organisms; return nutrients to ecosystems
E.
Detritivores - feeds on plant and animal remains and other dead matter (detritus)
F.
Scavenger – eats dead organism
V.
Feeding relationships - Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs and then to heterotrophs.
A.
Food Chains - a series of steps in which organisms transfer energy by eating and being eaten.
B.
Food Webs – a network of feeding relationships in an ecosystem.
Food web links all food chain.
C.
Trophic level - Each step in a food chain or food web is called a trophic level.

VI.
Ecological pyramids - a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.
A.
Energy Pyramid
1.
Shows relative amount of energy available at each trophic level.
2.
organisms use 90% of the energy for life functions and as heat loss
3.
10% of the total energy is converted into biomass and available to the next trophic level
4.
the higher the trophic level, the fewer the organisms
B.
Biomass pyramid
1.
Represents the amount of living organic matter at each trophic level
2.
The greatest biomass is at the base of the pyramid
C.
Pyramids of numbers
1.
Shows relative number of individual organisms at each trophic level.
VII.
Cycling of Matter
Materials, chemicals and nutrients are cycled through an ecosystem. They cycle through the biogeochemical cycles (biotic and abiotic factors).
A.
Water Cycle
1.
water moves between atmosphere, the Earth and the ocean
2.
sunlight provides energy that drives the cycle
3.
Evaporation – water changes from liquid to gas. The sun evaporates water from oceans, lakes, rivers and organisms; water is returned to atmosphere
4.
Transpiration – process of removing water from plants
5.
Precipitation – as water vapor cools in the atmosphere, it condenses and forms tiny droplets in clouds; water falls from the clouds as rain, snow, etc.
6.
groundwater - precipitation soaks into the soil; some of it is used immediately by plants or it seeps into layers of rock; flows much more slowly than surface water; major source of drinking water
7.
97.6% of the Earth’s water is in the oceans; 1.9% is in the ice caps and glaciers; 0.03% is freshwater; 0.5% is groundwater
Nutrient Cycles –Any chemical substance that an organism requires to live is a nutrient. The nutrients are passed between an organism and the environment.
B.
Carbon Cycle
1.
based on carbon dioxide
2.
photosynthesis brings carbon into ecosystem from atmosphere
3.
producers take in CO
2
from atmosphere and use carbon to build carbohydrates.
4.
consumers eat producers to get carbon
5.
cellular respiration releases carbon dioxide back into atmosphere
6.
geochemical process such as volcano releases CO
2
to the atmosphere
7.
human activities such as mining, burning of fossil fuels, cutting & burning of forests release CO
2 to the atmosphere
8.
In the ocean carbon is found in the calcium carbonate
9.
atmosphere and oceans also directly exchange CO
2
10.
Greenhouse Effect
Humans are increasing consumption of fossil fuels which increases the amount of carbon released into atmosphere and more heat from the sun is trapped

C.
Nitrogen Cycle
1.
Organisms need nitrogen to build proteins.
2.
Nitrogen gas makes up about 78% of the atmosphere.
3.
Almost all organisms cannot take in N
2 directly from the atmosphere.
4.
Only a few species of bacteria can use nitrogen directly. Such bacteria, which live in the soil and on the roots of plants called legumes, convert nitrogen gas into ammonia in a process known as Nitrogen Fixation.
5.
Decomposers - break down wastes and dead organisms & return nitrogen (in the form of ammonia) to the soil
6.
Other bacteria in the soil convert ammonia into nitrates (NO
3
), and nitrites (NO
2
).
7.
Some soil bacteria convert nitrates into nitrogen gas in a process called Denitrification and releases nitrogen into the atmosphere
D.
Phosphorus cycle
1.
Essential to living organisms because it forms part of DNA and RNA .
2.
Exists in the form of inorganic phosphate on land in rock and soil minerals, and in ocean sediments.
3.
Plants absorb phosphate from the soil & bind it into organic compounds.
4.
Phosphate washes into rivers and streams, where it dissolves & makes its way to the oceans, where it is used by marine organisms.

ECOLOGY NOTES - CHAPTERS 4
ECOSYSTEMS AND COMMUNITIES
I.
Climate / Soil
A.
Climate determined by:
1.
Absorption of sun’s energy (temperature)
2.
Heat transport - movement of air and water currents & precipitation
3.
Latitude – Earth has three main climate zones: polar, temperate, and tropical. Polar is cold and dry; equator is warm and wet.
4.
Land masses – shape & elevation
5.
Ocean currents - cold on west coast; warm on east coast
B.
Soil
1.
Organized mixture of organic matter, water, air and organisms
2.
Fragmentation - physical break-up of rock
3.
Humus - decomposed organic matter in the soil
It increases texture and water holding capacity.
II.
Biotic factors - The biological influences on organisms within an ecosystem.
Abiotic factors - Physical, or nonliving, factors that shape ecosystems.
III.
Habitat - The area where an organism lives (biotic + abiotic factors)
IV.
Niche - full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions.
A niche includes: type of food the organism eats, how it obtains this food which other species use the organism as food physical conditions it requires to survive when and how it reproduces
According to competitive exclusion principle, no two species can share the same niche in the same habitat at the same time. However, different species can occupy niches that are very similar.
V.
Climate is determined by - temperature and precipitation
Microclimate
– climate that exists over a small area & that is different from the climate of surrounding region.
VI.
Ecosystems are constantly changing in response to natural and human disturbances.
Older inhabitants gradually die out and new organisms move in, causing further changes in the community. This series of predictable changes that occurs in a community over time is called
"Ecological Succession"
Pioneer species - The first species to populate an area at the beginning of the process of primary succession
VII.
Biomes
Large, geographical area that has a distinct climate and certain dominant communities (species of plants and animals)
Each biome is defined by a unique set of abiotic factors—climate—and a characteristic assemblage of plants and animals (ecological community).
There are both terrestrial (land) and aquatic (water) ecosystems

VIII.
Terrestrial Biomes
A.
Tropical Rainforest
1.
found along the equator
2.
increased temperature, increased rainfall (250 cm/yr), increased humidity
3.
little humus and organic litter; poor soil
4.
very high biodiversity
5.
was 20% of Earth’s surface, now only 7 % due to deforestation
B.
Tropical Dry forest
1.
Rain fall is highly seasonal rather than year-round (alternate wet and dry season)
2.
Tall deciduous trees drop their leaves during a particular season each year
3.
Rich soil subject to erosion
C.
Temperate Rainforests/North Western coniferous forest
1.
50 o - 60 o N latitude
2.
increased rainfall; moderate temperatures
3.
found in the Pacific NW
4.
includes redwoods, spruces
C.
Temperate Deciduous Forests
1.
30 o
- 50
o
N latitude
2.
trees drop leaves in the fall to save energy
3.
has 4 distinct seasons
4.
rich layer of humus; fertile soil
5.
found in North America, Europe, Asia
6.
includes maples, beeches, oaks, etc.
7.
leaves are broad and thin with large surface areas for maximum light absorption
8.
seed and underground stems survive winters
9.
birds migrate to warmer climates
10.
some mammals hibernate to reduce their metabolic rate in winter
D.
Taiga/Boreal Forest
1.
northern coniferous forests just south of Arctic Circle
2.
long, cold winter – 6 - 10 months
3.
short growing seasons enhanced by constant sunlight
4.
snow precipitation
5.
conifer leaves are thin and waxy to retain water
6.
cones protect seeds
7.
birds migrate south in winter
8.
animal fur is thick and insulated
E.
Tropical Savannas
1.
inland, around the equator
2.
main vegetation is grasses
3.
low precipitation and moisture
4.
frequent fires
5.
large, underground root systems to survive the dry season and fires
6.
thorns and sharp leaves to protect from herbivores
7.
large herbivores specialized for different levels of vegetation
8.
migratory
9.
high number of carnivores

F.
Temperate Grasslands
1.
inland part of continent
2.
main vegetation is grasses
3.
very fertile soil; little rainfall
4.
was 42% of Earth’s surface, now only 12%
5.
fires are common
6.
grasses are perennials - survive year to year
7.
few trees can survive
8.
root system is dense to protect from droughts
9.
few large herbivores
10.
underground burrows
G.
Temperate woodland and shrub land
1.
Semi-arid climate - hot dry summer, cool moist winter
2.
Nutrient poor soil
3.
Mixture of shrub and open woodlands
4.
Plants contain flammable oils and fire is a constant threat
H.
Deserts
1.
many kinds of deserts
2.
less than 25 cm of rainfall per year
3.
soil is rich in minerals but little organic matter
4.
plants have thick, fleshy stems with wax covering
5.
spines protect against predators
6.
sudden growth spurts
7.
animals go through estivation - summer sleep
8.
most animals are nocturnal
9.
animals absorb water from food
I.
Tundra
1.
Permafrost - permanently frozen layer of ground 6 inches below the surface
2.
dotted with pools of water – lots of insects
3.
no trees
4.
rocks are covered with mosses and lichens
5.
plants are short and woody
6.
plants reproduce quickly in short summer
7.
birds are migratory
8.
reindeer and caribou move to find food
9.
small rodents burrow underground
VIII.
Aquatic Ecosystems
Aquatic ecosystems are determined primarily by the depth, flow, temperature, and chemistry of the overlying water.
A.
Freshwater Ecosystems
1.
flowing – water ecosystem - rivers, streams, creeks, brooks; flow over land
2.
Standing - water ecosystem – lakes, ponds; circulation of water within
3.
freshwater wetlands - water either covers the soil or is present at/near the surface for at least part of the year; very productive; bogs, marshes and swamps

B.
Estuaries Ecosystems
1.
formed where rivers meet the ocean
2.
mixture of salt and fresh water
3.
affected by the rise and fall of the ocean tides
4.
salt marshes, mangrove swamps
IX.
Marine Ecosystem
Photosynthesis is limited to this well-lit upper layer known as the photic zone.
It is down to a depth of 200 meters where algae and other producers grow.
Below the photic zone is the aphotic zone which is permanently dark where only chemosynthetic autotrophs can survive.
The ocean can be divided into zones based on the depth and distance from shore:
1.
Intertidal Zone – regular and extreme changes in surroundings; tides, waves, currents
2.
Coastal Ocean – extends from the low-tide mark to outer edge of continental shelf; has kelp forests
3.
Coral Reefs – warm, shallow water of coastal, tropical oceans; very high diversity of organisms
4.
Open Ocean – edge of the continental shelf and extends outward; low levels of nutrients; wide open spaces
5.
Benthic Zone – ocean floor; dependent on food that comes down from surface; life without light and photosynthesis
X.
Community Interaction
A.
Predation (+/-) – predator kills and eats prey; there is a consumer and a resource; examples are a lion – gazelle; snake – mouse
B.
Competition (-/-) – species and organisms compete over the same limited resources
1.
interspecific – competition between different species; examples are fox and coyote, yellow jacket and honeybee
2.
intraspecific - competition within the same species; examples are wolf territories; lions fighting for food
Symbiosis – close relationship between 2 organisms that may help or harm them.
Following 3 are examples of symbiotic relationships.
C.
Parasitism (+/-) – a parasite is an organism that lives in or on another organism; a host is an organism that provides nutrients to the parasite; most parasites do not kill their hosts; examples are ticks, tapeworms
D.
Mutualism (+ / +) – cooperative partnership between 2 species; both species can benefit; 2 types:
1.
faculatative – both species can survive with or without it; example is vulture and lion kill
2.
obligate - an organism needs a particular species to survive; example is tropical hummingbird and flower
E.
Commensalism - (+ / 0) – one species benefits and the other species is neither helped nor harmed; example is barnacles on whale
F.
Amensalism (- / 0) Ex - penicillium secrete penicillin that kills bacteria.