Ecology & Ecosystems

Ecology

• a branch of the biological science that studies the interaction’s between an organism & its environment

  • Layers of organization

    • Organisms>Population>Communities>Ecosystems>Biomes>Biosphere

Biosphere

• The Lithosphere

• The Atmosphere

• The Hydrosphere

  • A terrarium (sealed/closed system)

    • Reason:

      1. The plants & the soil in the terrarium release water vapour - essentially recycling water

      2. The vapour is then collected unto the walls of the vessel & flows down to the soil

         → Terrariums are self-nourishing, which is why they require little maintenance if sealed

         • one input: the sun & it’s sunlight

Biomes

• Terrestrial part of the biosphere

  • Diff. Biomes are distinguished by their climates & the soils & species they support (moisture & temp. defines most biomes)

Aquatic Life Zones

• Like a biome but in the ocean

  • Defined by temp., nutrients, & light

    • Richest regions are estuaries (where river dumps into the ocean, shallow areas)

      • Lots of penetration & nutrients

      • Most productive area; good for fisheries

Ecosystems

• 2 parts of ecosystem: living - biotic & nonliving - abiotic

  • Abiotic Factors:

    • Physical - rock

    • Chemical - minerals

    • Range of Tolerance - taking in physical and chemical energy

  • Biotic Factors:

    • Other species in ecosystem

    • food supply

    • preparation

    • competition

    • has a range of tolerance

Habitat & Ecological Niche

• Habitat: where a species is found

• Niche: where it is found & what it does

  • Deer lives in Assiniboine forest - Habitat

  • Deer lives on Assiniboine forest, eats grass, & feeds coyotes - Niche

    • Now TWO have the same niche (one will always outperform the other)

    • Deer & Elk, Owl & Hawk (although similar they hare clear differences that separates them)

Food Chains & Webs

• Producers (basic system;base of all food)

  • organism that can take sunlight & turn it into carbohydrates

    • algae, etc.

• Consumers

  • consumes producers

• Decomposers

  • trapped nutrients; when you die it gets released back into the ecosystem

• Other terms -

  • Omnivore - multiple levels of feed

  • Herbivore - only eats plants

    • Ex:

  • Carnivore - only eats meat

    • ex:

      • energy flows in 1 way -

• ex: Cod is a stable food system - when it breaks down, cant be rebuild but losing a single factor wouldn’t

Energy

• Energy: capacity to do work

  • Two Types of Energy:

    • Potential energy: stored in the object

      • Ex: Ball on top of hill or chemical bond

    • Kinetic Energy: energy of motion

  • 1st Law of Thermodynamics:

    • Energy can be neither created or destroyed, but only charged from one form to another

  • 2nd Law of Thermodynamics:

    • In any energy conversion, there will be some loss as heat (from one type of energy to another)

Efficiency in the Food Chain

Nutrient Cycles

• Nutrients unlike energy are recyclable

• Cycles that moves chemicals around the biosphere are called biogeochemical

  • driven by life process

Carbon Cycle

Balance & Imbalance in Ecosystems

• Ex: Lake Victoria & Nile perch

  • Lake Victoria have been for a long time; Nile perch

    • British: added Nile Perch and it ate all of the Cichlids

      • Nile Perch (oily fish) preserved

        • resulted in a disruption of ecosystem

• Ex: Water hyacinth in Florida

  • around 1920s, Florida Everglades now becomes closed because there was no competitor

• Stable Ecosystem: things changed a little from day to day, or month to month, or in annual cycles, but generally stay the same

• Dynamic equilibrium: doesn’t stay exactly the same but oscilates around a central point

Ecosystem Stability

• Total # of living species is constant (or almost) year after year

• The same species are present every year; &

• The population (P) of each species is roughly the same every year

Population Growth in Ecosystems

• Populations of various species are controlled by many factors, some of them are biological or biotic, & some of them not or abiotic

• Biotic Growth Factors:

  • Reproductive rate

    • Ex: High Reproductive Rate: Rats & Bunnies & Dandelions & Mosquitoes

  • Adaptability:

  • Ability to migrate:

    • Ex: Dandelions; mobile seeds

  • Competitiveness

    • Ex: Nile Perch & Water Hyacinth

  • Food Supply:

    • Ability to eat & survive

      • Ex: Pandas & Koalas

  • Abitic Growth Factors:

    • Favourable Light: Plants under Water Hyacinth

    • Favourable Temp. or moisture

    • Etc

  • Biotic Reduction Factors:

    • Predators

      • Ex: Nile Perch

    • Parasites

      • Presence or absence of parasites

        • Ex: Moose population is decreasing in Quebec due to Ticks

    • Food Shortage

      • Not enough grass-decrease in pop.

    • Loss of Habitat

      • Ex: Less sea ice in Manitoba = decrease in Polar Bears

  • Abiotic Reduction Factors

    • Bad Weather

      • Mosquitoes

    • Water Shortage

      • Ex: A pond has lessened water = affects frog pop.

    • Pollution

Resisting Change

• If an ecosystem is stable. it resists change, & the system is said to have inertia

• If it changes significantly,& then bounces back to something like its original state, it is said to have resilience

  • Ex: Singapore’s cold weather is 24 and the hottest is 31

Human Impact on Ecosystems

• Introducing new species

  • Ex. Nile perch, (human introduction)

  • Africanized killer bees

  • Rabbits, displacing natural herbivores in Australia

    • ate all the food sources

      • Rabbits that did survive had a resistance to virus (bred like rabbits)

• Removing a species

  • Kaibab Plateau in Arizona (modification of an ecosystem)

• Introducing parasites

  • Bacillus thuringiensis (BT)

    • natural pesticide