2.1 - StructureIB Topics 2.1.1-2.1.7

Topic 2 – The Ecosystem

Key Words (define and provide a local example of each)

Biotic Abiotic Trophic Level Producer Consumer Autotroph Heterotroph Carnivore Herbivore Omnivore

Species Population Community Habitat Ecosystem Niche Competition Mutualism Parasitism Predation

Biotic and Abiotic Components

Biotic All living

components of the ecosystem

Ex:

Abiotic All non-living

components of the ecosystem

Ex:

Food Chains The position an organism occupies in a

food chain is called the trophic level.

Local Food Chain Example:

Food Webs Ecosystems

contain many interconnected food chains

Pyramid of Numbers A graphical model

of the number of organisms in a food chain

Pyramid of Biomass A graphical model

of the amount of biomass present in a food chain at a certain point in time

Pyramid of Productivity A graphical model

of the rate of energy production over time

Top CarnivoresBioaccumulation

Toxins (pesticides, etc.) can be retained in fat tissue

Biomagnification

Each successive trophic level gains more toxin

2.2 – Measuring Abiotic ComponentsIB Topics 2.2.1-2.2.2

Topic 2 – The Ecosystem

Significant Abiotic Factors Terrestrial

Ecosystem Marine

Ecosystem Freshwater

Ecosystem

2.3 – Measuring Biotic ComponentsIB Topics 2.3.1-2.3.5

Topic 2 – The Ecosystem

Estimating abundance of organisms Counting the

number of organisms is almost always done using an estimate

Lincoln Index A mathematical

model to estimate population size

Capture-mark-release-recapture

Example 1

13 deer were caught and marked

14 deer were caught the second time and 5 were marked

Example 2

75 Ladybugs were caught and marked

80 Ladybugs were caught the second time and 3 were marked

Quadrats A square of area

used to measure the population of non-mobile organisms Can help to

calculate population density and percentage cover

Diversity1. The number of

different species

2. The number of individuals of each species

Simpson’s Diversity Index Used to compare

diversity between areas

High value of D implies stable ecosystem

Low value of D implies unstable ecosystem

2.4 – BiomesIB Topics 2.4.1-2.4.2

Topic 2 – The Ecosystem

Biomes A collection of

ecosystems that share similar climactic conditions

Rainforest

Desert Tundra Temperate Forest

Grassland

Prevailing Climate

Location

Sun Exposure

Precipitation

Limiting Factors

Rainforest

Desert Tundra Temperate Forest

Grassland

Prevailing Climate

Hot, Humid, Rainy

Hot, Dry Cold Seasonal Varied by location

Location Near Equator

Varied, where no

precip

Poles 40-60o N Latitude

Varied, where some precip

Sun Exposure

High Varied, usually

high

Low Medium, Seasonal

Varied

Precipitation

High None Snow Medium, Seasonal

Low

Limiting Factors

Too much precip.

Not enough water

Too cold, permafrost

Seasons Low precip

2.5 – FunctionIB Topics 2.5.1-2.5.7

Topic 2 – The Ecosystem

Photosynthesis

Respiration

Energy Flow Through the Ecosystem

Gross Primary Productivity (GPP)

The amount of energy produced by producers

Net Primary Productivity (NPP)The amount of

energy stored by producers and available to consumers

Gross Secondary Productivity (GSP)

The amount of energy consumed by consumers

Net Secondary Productivity (NSP)The amount of

energy stored by consumers and available to the next trophic level

Simplified Example:

2.6 – ChangesIB Topics 2.6.1-2.6.7

Topic 2 – The Ecosystem

Carrying Capacity The maximum

number of organisms an ecosystem can support sustainably over a long period of time

Limiting Factors Factors that limit

the amount of individuals in an ecosystem

Tolerance Species will be most abundant within a

certain range of a limiting factor

Population CurvesS Curve

Reaches carrying capacity and stabilizes J Curve

Unchecked population growth

Limiting Factors Density-

dependent factors Limit population

size more as population increases

Limiting Factors Density-

independent factors Limit population

size regardless of population size

r-strategists Opportunistic

species Inhabit

unstable/changing environments

Reproduce early/often, mature quickly

Slow growing/maturing species

Few offspring Long lifespans

K-strategists

C-strategists

In between r & K

Survivorship Curve

SuccessionA natural increase in the complexity of

the structure and species composition over time

Succession

Primary

Occurs on uncolonized substrate (rock)

Secondary Occurs where a

previous community has been destroyed

Zonation Different

types of ecosystems in a gradient due to elevation or resources Ex: Altitude

zonation on a mountain

Climax Community A stable, complex

ecosystem in a late stage of succession

Characteristics:

2.7 – Measuring ChangesIB Topics 2.7.1-2.7.3

Topic 2 – The Ecosystem

Environmental Impact Assessment

Before any development gets permission to begin, an EIA must be done

Predicts the potential impacts on habitats, species, and ecosystems

Baseline Study Habitat type Species list Species diversity Endangered

species Land use Hydrology Human population Soil quality