Lecture # 1 Ecological Hierarchy & Ecosystem Formation Unit 1: Ecology

1.We are part of the environment along with all of Earth’s other organisms.

2. All of Earth’s inhabitants are interwoven in a complex web of relationships. 3. Interactions of the parts affect the whole system.

4.Removing, altering, or damaging one part of the whole will affect the whole.

Many consequences of doing so are unpredictable, so understanding how the “whole” operates is critical for humankind if we are to survive as a species on this planet.

What is ecology? Ecology- the scientific study of interactions between organisms and their environments, focusing on energy transfer It is a science of relationships.

What exactly is ‘the environment’? Everything that surrounds us! The environment is made up of two factors: Biotic factors- all living organisms inhabiting the Earth (ex: grass, trees, rabbits, bacteria, etc) Abiotic factors- nonliving (physical) parts of the environment (ex: temperature, soil, light, moisture, air currents)

Abiotic or Biotic? copyright cmassengale8 Biotic

Abiotic or Biotic? copyright cmassengale9 Abiotic

Abiotic or Biotic? copyright cmassengale10 Abiotic

Organization levels of biology

Organism Population Community Biosphere Ecosystem

OrganismOrganism- any unicellular or multicellular form exhibiting all of the characteristics of life; an individual. The lowest level of organization

PopulationPopulation-a group of organisms of one species living in the same place at the same time that interbreed and compete with each other for resources (ex. food, mates, shelter)

What is a species? Species- Members of a population that look alike and have the ability to produce fertile offspring Canis lupus

CommunityCommunity- several interacting populations that inhabit a common environment and are interdependent.

EcosystemEcosystem- populations in a community and the abiotic factors with which they interact Marine Terrestrial

Ecosystem= biotic + abiotic factors Ecosystem boundaries are not always obvious. They depend on how the ecosystem is being studied. Example - a single rotting log on the forest floor vs. the entire forest itself.

Biomes- groups of related terrestrial ecosystems Example: rainforest, grassland, desert

BiosphereBiosphere- the region on earth where life exists. This includes air, land, fresh water, and salt water. The highest level of organization

Biodiversity - The variety of species living within an ecosystem, biome or planet.

Some parts of the world have greater biodiversity than others Do you think that desert or the rainforest has greater biodiversity?

Habitat vs. Niche Habitat- the place in which an organism lives out its life (address) Niche - the role a species plays in a community (job)

Habitat vs. Niche A niche is determined by the tolerance limitations of an organism, or limiting factors. Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

Amount of water Amount of food Temperature Examples of limiting factors

Lecture #1 Part II Ecological Succession Unit 1: Ecology

Ecological succession- the regular progression of species replacement over time in a new or disturbed community.

1) Biomass increases over time. 2) An increase in the number & proportion of longer-lived species. 3) Increased species diversity. Succession on Mt. St. Helens Succession shows some general trends that include:

There are two types of terrestrial succession 1)Primary Succession 2)Secondary Succession

This colonization of new sites by communities of organisms takes place on bare rock Primary succession: The establishment and development of an ecosystem in an area that was previously uninhabited

New bare rock comes from 2 sources 1.A volcanic lava flow cools and forms rock –This is how the Galapagos islands and the Hawaiian islands formed!

New bare rock comes from 2 sources 2. Glaciers retreat and expose rock

How does the process begin? Pioneer organisms- the first organisms to colonize a new site –Ex: lichens are the first to colonize lava rocks These guys are TOUGH! They thrive where no other species can.

What do they do and what happens next ? –As lichens add organic matter and form soil, mosses and other plants can colonize and grow.

–As organic matter continues to accumulate, other species move in and change the environment further. First fast growing plants, then slower growing plants. –Over time, more and more species can find suitable niches and survive.

Primary succession-

Is there an ‘end’ to succession? Climax Community - a stable, mature community that undergoes little or no succession. ** This is not necessarily a ‘permanent’ community however. What would cause it to change?

Answer: A changing environment!

Secondary succession- Definition: Sequence of community changes that takes place when a community is disrupted by natural disaster or human actions This type of succession occurs in areas where there HAD been previous growth. Because of this, the process is much faster than primary succession.

What can cause secondary succession to occur? 1)Forest fire The regrowth that happens after a fire levels a portion of a forest.

What can cause secondary succession to occur? 2. Abandoned Agricultural Field Native plant life from the areas surrounding the agricultural field reinvade the area.

Secondary succession-

Case Study- Yellowstone National Park 1988 – Park map showing areas (1.6 million acres) burned by the series of fires.

Yellowstone National Park 1988 fires – The immediate aftermath. Photo: National Parks Service

Yellowstone National Park One year after the fires Note the appearance of fireweed Photo: National Parks Service

Yellowstone National Park Ten years after the fires (1998) Photo: National Parks Service

Yellowstone National Park Twenty years after the fires (2008)

Is the Yellowstone Case study an example of primary or secondary succession?

Case Study - Chernobyl In April, 1986, a nuclear power plant in the former USSR experienced a core meltdown and a catastrophic release of radioactivity into the environment.

Chernobyl Surrounding towns and villages had to be immediately, permanently abandoned.

Chernobyl – Twenty Years Later

Pripyat town square.

Chernobyl – Twenty Years Later

A local highway.

Is the Chernobyl Case Study an example of Primary or Secondary Succession?

Take 2 minutes to describe what succession is, and to identify the similarities and differences that exist between primary and secondary succession.