Ecology and Human Impact

Population

Single group/species in an area (define boundary)

Community

all the populations in an area (living populations)

Ecosystem

• made up of biotic (any living part of an ecosystem that an organism interacts with) and abiotic factors (any non-living part of an ecosystem)

• Movement of matter and energy between organisms and their environment is a basic characteristic of an ecosystem

• Living things obtain the matter and energy they need from biotic and abiotic factors

Biome

Large areas with certain climates (grassland)

Biosphere

all of Earth’s ecosystem together

Habitat

A habitat is a specific area in an ecosystem that a species calls “home”

Ecological Relationships

• Predation/Herbivory (+/-)

  • Consumers that eat other consumers (predators eat prey)

• Competition (-/-)

  • Occurs with organisms of the same/different species

  • Has similar/same niche and has to fight for limited resources in their area

  • One will outcompete the other

• Mutualism (+/+)

  • (ex: flowers & bees)

  • both organisms are benefited

• Commensalism (+/0)

  • (ex: whale & barnacle)

  • one organism is helped while the other is unaffected

• Parasitism (+/-)

  • (Ex: ticks & dogs)

  • A parasite lives on/in another organism (host) for food or shelter

  • Parasite is helped while host is harmed

  • Evolve with the host and have characteristics that help them adapt to a specific host

Carrying Capacity

The maximum # of individuals of a given species that an ecosystem can support

Limiting Factors

• Limiting factors determine the carrying capacity of an environment for a species

• Examples:

  • competition

  • predation

  • parasitism

  • disease

  • climate and weather conditions (natural disasters)

Competitive Exclusion Principle

2 species that occupy the same niche at exactly the same time will begin competition and one will dominate the other

Niche

• The organism’s role (way of life) in the environment

• The abiotic and biotic factors the organism interacts with (what it eats, how it behaves, interaction between other organisms)

• Conditions it needs to survive (species temperature and nutrients/food)

• The niche of an organism determines its habitat

Exponential Growth

Under ideal conditions with unlimited resources, a population will grow exponentially

Logistic Growth

When a population’s growth slows and then stops, following a period of exponential growth, it is called logistic growth

Producers

• Get energy from the sun

• Organisms that produce their own nutrients

  • Ex: Photosynthesis

  • Photoautotrophs use photosynthesis

  • Producers=Autotrophs

Consumers

• Organisms that rely on other organisms for energy and nutrients

  • Herbivore, Carnivore, omnivore

• Other consumers:

  • decomposer (ex: bacteria and fungi - release enzymes to break down matter), scavenger (ex: vultures), detritivore (worms)

    • Those consume dead/decaying matter

Food Chains and Food Webs

Food Chains:

• A food chain energy is transferred from one organism to another in a series

• Linear relationship

Food Webs:

• Shows a network (shows biodiversity) of feeding organisms

• Higher biodiversity will show a more complex food

• Indicates stable ecosystem

• Trophic level refers to each step in a food web

Ecological Pyramid

• Models that show relative amounts of energy or matter within each trophic level

  • Producers are always at the base of pyramid

  • Primary consumers = Herbivores that eat producers

  • Secondary consumers = carnivores that eat primary consumers

  • Tertiary consumer = carnivores or apex predator that eat primary/secondary consumers

Pyramid of Energy

• relative amount of energy available for each trophic level (10% rule)

  • Energy level decreases by 10% as it goes up the pyramid

• Each trophic level uses energy for its own metabolism

  • Releasing heat

Water Cycle

• Evaporation: The sun’s heat causes waters to turn from liquid → vapor (gas) that rises into the atmosphere

• Transpiration: evaporation from trees/plants

• Condensation: water vapor in the atmosphere turns from vapor → liquid, the water forms together into clouds

• Precipitation: water in the clouds fall down to Earth as rain, sleet, or snow

• The water then can either be absorbed into the soil to turn into groundwater or the water flows back to streams, rivers, and eventually the ocean (run off)

Carbon Cycle

• Trees/producers take in carbon from atmospheric carbon dioxide for photosynthesis

• Consumers that eat the producers consume the carbon and the carbon travels throughout the food web/food chain

• Humans/animals release carbon dioxide into the atmosphere by cellular respiration

• Decomposers break down decaying matter which releases carbon into the atmosphere or carbon can go into the soil where it can be stored for long times and can be turned into fossil fuels

• Combustion involves burning fossil fuels/carbon sink which can release carbon into the atmosphere

• Atmospheric carbon dioxide dissolves in water (oceans, lakes)

  • Helping to make sediments & rocks

Nitrogen Cycle

• Atmospheric nitrogen can be converted into ammonia by nitrogen fixing bacteria in the soil (nitrogen fixation)

• Then the ammonia can be turned into nitrites by nitrifying bacteria and then into nitrates which can be absorbed by plants (nitrification)

• Animals then obtain nitrogen by eating plants or consuming other animals that have eaten the plants

• Not all nitrates are absorbed by plants and denitrifying bacteria turns the nitrates back into nitrogen gas and released into the atmosphere (denitrification)

Keystone Species

• Plays a vital & unique role in maintaining, structure, stability, and diversity in an ecosystem

  • Ecosystem engineers: create habitats

    • Beavers, mangrove, coral

  • Predators: population control

    • sea otters, wolves

Biodiversity

• Species diversity

• Genetic diversity

• Ecosystem diversity

Biodiversity Benefits

• Contributes to medicine and agriculture

• Enables organisms and ecosystems to adapt to environmental change

Biodiversity and Ecosystem Resilience

• Resilience - ability to recover after a disturbance.

• The more biodiversity an ecosystem has, the more resilient it is likely to be. 

Ecological Succession

A series of more-or-less predictable events that occur in a community over time.

Primary Succession

Succession that begins in areas that have no remnants
of an older community

Pioneer Species

The first species to colonize barren areas

Secondary Succession

Succession that occurs when a disturbance affects an existing community but doesn’t completely destroy it

Succession After Natural Disturbances

Patches of climax communities may be in different stages of secondary succession due to multiple disturbances.

Invasive Species

A non-native species that can disrupt an ecosystem

• No natural predators

• Can often outcompete native species