Download The Biosphere

The Biosphere
Chapter 3
What is Ecology?
scientific
study of interactions among
organisms and between organisms and
their environment
Biosphere
 Combined
portions of the planet in which all of
life exists, including land, water and air or
atmosphere
Extends from 8 kilometers above Earth’s
surface to 11 kilometers below the surface of
the ocean
Interactions and Interdependence
 Interactions
within the biosphere produce a
web of interdependence between organisms
and the environment in which they live
Levels of Organization
 Individual:
interactions between an organism and
its surroundings
 cottontail rabbit
 Population: groups of individuals that belong to
the same species and live in the same area
group of cottontail rabbits
Levels of Organization
 Communities:
different populations that live
together in a defined area
 rabbits, coyotes, ravens, lizard
 Ecosystem: collection of all the organisms that
live in a particular place, together with their
nonliving, or physical, environment
 rabbits, coyotes, ravens, lizard, rocks, dirt,
climate, water
Levels of Organization
 Biome:
group of ecosystems that have the same
climate and dominant communities
 desert, tundra, tropical rain forest
 Biosphere: planet Earth
Ecological Methods
 Three
approaches to ecological research:
 Observing: Use of 5 senses to ask ecological
questions
 Experimenting: Used to test hypotheses
 artificial environment in a lab
 within natural ecosystems
Ecological Methods
Modeling:
Used to gain insight into complex
phenomena such as the effects of global
warming
may include mathematical formulas based on
data collected through observation and
experimentation
 predictions tested by further observations and
experiments

Energy Flow
 Energy
flows from the sun or inorganic
compounds to producers.
 Consumers eat producers to get energy.
 The primary source of energy on Earth is the sun!!
Producers
– “self feed”
 Use sunlight to create carbohydrates via
photosynthesis
 Ex – Plants, algae and some bacteria
 Some bacteria create organic compounds from
inorganic chemicals – Chemosynthesis
 Autotrophs
 Live
in remote places.
Producers
Consumers
– “Different food”
 Must eat to obtain energy.
 Ex – animals, fungi, some protists
 Heterotroph
Types of Heterotrophs
– eats plants
 Carnivore – eats animals
 Omnivore – eats plants and animals
 Detritivore – eats detritus (plant and animal
remains)
 Herbivore
 Ex-
snails, crabs, earthworms
 Decomposer
 Ex
– breaks down organic matter
– bacteria and fungi
Feeding Relationships
 Energy
flows through an ecosystem in one
direction,
 from the sun or inorganic compounds 
autotrophs (producers)  various heterotrophs
(consumers).
Food Chain
 A series
of steps in which organisms transfer
energy by eating and being eaten.
i.e. Wheat  mouse  snake  hawk
Food Chain Example
Food Web
 Network
of complex interactions formed by
the feeding relationship among the various
organisms in an ecosystem.
Trophic Levels
 Each
step in a food chain or food web
1st level = producers
2nd, 3rd, or higher levels = consumers
 Usually no more than 5 levels because 90% of
energy is lost at each level.
Ecological Pyramid
 A diagram
that shows the relative amounts of
energy or matter contained within each
trophic level in a food chain or food web.
 Energy, biomass, and population numbers
can all be represented by a pyramid.
Ecological Pyramid
Cycles of Matter
 Recycling
in the Biosphere
 Matter is recycled within and between
ecosystems.
 Matter moves through an ecosystem in
biogeochemical cycles.
Water Cycle
Carbon
Cycle
Nitrogen Cycle
N2 in Atmosphere
NH3
NO3and NO2-
Nitrogen Cycle
 78%
of Earth’s atmosphere is Nitrogen gas = N2
Nitrogen containing products:
Ammonia (NH3)
Nitrate ions (NO3-)
Nitrite ions (NO2-)
Nitrogen is needed for protein and nucleic acid
synthesis
Nitrogen Cycle
 Converting
nitrogen gas into ammonia is called
nitrogen fixation.
Only certain types of bacteria can do this.
Plants use the converted products (NH3, NO3- ,&
NO2-) to make plant proteins.
 Some bacteria convert nitrates into nitrogen gas
(denitrification).
Phosphorus Cycle
Phosphorus Cycle
 Phosphorus
is important for the formation of
DNA and RNA molecules.
 Phosphorus is not very common and does not
enter the atmosphere, instead it is found mostly
on land in rock and soil.
Primary Productivity
 The
rate at which producers create organic matter.
 Determines the size of the community.
 Limited by availability of nutrients.
– phosphorus (P), nitrogen (N), potassium (K)
 Marine – nitrogen
 Fresh water - phosphorus
 Land
Algal Bloom