IB Environmental Systems and Societies Unit 2 Ecosystems

Ecosystems

made up of the organisms and physical environment and the interactions between living and non-living.

Species

A group of organisms sharing common characters that interbreed and produce

Population

a group of organisms of the same species including same species, living in the same area, at the same time, and can interbreed.

Population density

Average number of individuals in a stated area.

What are the factors for population density?

Natality (birth rate), mortality (death rate), migration (immigration and emigration)

Habitat

The environment a species lives in.

Abiotic Factors

Non-living, physical factors that influence an organism and ecosystem.

Biotic Factors

The living components of an ecosystem.

Biomes

Collections of ecosystems sharing similar climate conditions

What are the three distributions of biomes?

Insolation, precipitation and temperature

Insolation

Amount of solar energy

precipitation

amount of rain/snow fall

temperature

A measure of heat

Limiting Factors

Slow down the growth of a population as it reaches carrying capacity.

Carrying capacity

The maximum number of species or "load" that can be sustainably supported by a given area.

Respiration

Transformation which releases chemical energy from organic molecules

Photosynthesis

Transformation which takes energy captured by the plant and stores it as chemical energy.

Ecosystem

Community of organisms that depend on each other and the environment they live in.

Food chains Process

Producer - primary consumer - secondary consumer - tertiary consumer - apex predator - decomposers

Food Webs

The complex network of interrelated food chains

10% rule (trophic efficacy)

Only about 10% of a trophic levels energy travels up to the next trophic level

Max number of trophic levels a food chain/web can have before there is not enough energy to continue

5-6 levels.

Niche

How an organism makes a living

Trophic Level

The position an organism occupies in the food chain (producer, primary consumer, etc)

Producers

(Autotrophs) organisms that create their own food

Consumers

Heterotrophs. Any organisms that gain nutrition from another.

Decomposers

Organisms that break down organic matter (fungi and rabbits)

Herbivores

Heterotrophs that are primary consumers

Carnivores

Heterotrophs that are secondary consumers or greater.

Omnivores

Heterotrophs that feed at any trophic level (Badgers)

Detritivores

Heterotrophs that consume dead organic matter. Break down by oral digestion

Types of Decomposers

Detritivores, scavengers and saprophytes.

Scavengers

Eat feces

Saprophytes

Externally digest organic matter by secreting enzymes and absorbing nutrients.

Competition

When 1 or more species have limited access to resources. has a negative impact on all impacted species.

Intraspecific Competition

Competition between members of the same species for food, water, territory, mating, etc

Interspecific Competition

Competition between different species for the same.

Predation

One animal (predator) eats another animal (prey)

Herbivory

An organism (herbivore) eating a green plant.

Parasitism

One species (parasite) lives in or on another (host). DOES NOT KILL HOST.

Mutualism

Relationship where all benefit and none suffer. Symbiotic relationship

Ecological Pyramids

Graphical models of the amount of living material stored each trophic level.

Pyramid of numbers

Shows the number of organisms at each trophic level

Advantages of Pyramid of Numbers

Simple and easy overview + good for comparing seasonal change.

Disadvantages of Pyramid of Numbers

Size not considered + age not considered + numbers can be inaccurate.

Pyramid of biomass

contains the biomass (individual number TIMES numbers) + quantity of dry organic material in an organism.

Advantages of Pyramid of Biomass

Overcome problems with PoN

Disadvantages of Pyramid of Biomass

Uses samples so impossible to measure exactly + organisms must be killed to be measured (unethical)

Pyramid of Productivity

Contains the flow of energy through each trophic level

Advantages of Pyramid of Productivity.

Shows the actual energy transferred to each level

Disadvantages of the Pyramid of Productivity

Difficult and complex to collect energy data + omnivores organisms defy trophic levels

Succession

Change in the community structure of a particular area over time

Zonation

The arrangement or patterning of plant communities or ecosystems into bands in response to change over a distance in some environmental factor.

Example of Succession

Annual plants - perennial plants - grasses - shrubs - softwood trees (pines) - hardwood trees

Example of Zonation

Mount everest - eternal snow and glaciers - alfine meadows - subalfine meadows - coniferous forests

Primary Succession

Colonization of newly created land by organisms (rock)

Primary succession example

Bare rock

Secondary Succession example

Weeds and wildflowers grow

Secondary succession

Occurs in places where a previous community has been destroyed (forest/fire). + is faster than primary succession because of the soil and seed bank available.

Pioneer

Earliest community of succession

Climax Community

Last and final community

Order of Succession

Pioneer species - intermediate species - climax community

Sere

The change from pioneer to climax.