Ecosystem Dynamics and Factors

Ecosystems and Environmental Factors

  • Ecosystems vary in water availability; too much or too little water can be catastrophic.
  • Ecology 102, Section 1 focuses on factors causing ecosystem changes, their effects on stability, and the changes within ecosystems.

Defining Ecosystems

  • Ecosystems include all organisms and environmental factors interacting in a specific area.
  • Interactions between organisms, like predator-prey relationships, are part of the ecosystem.
  • Two main categories of ecosystems:
    • Aquatic: Contained within a body of water.
      • Marine: High salt concentration.
      • Freshwater: Low salt concentration.
    • Terrestrial: Not contained by a body of water; located on dry land.

Factors in an Ecosystem

Biotic Factors

  • Biotic factors are living factors (BIO = life).
  • Include all organisms and their interactions within an ecosystem.
  • Example: Clownfish and anemone interaction.

Abiotic Factors

  • Abiotic factors are non-living parts of an ecosystem.
  • Examples: air temperature, soil type, lightning, climate.

Carrying Capacity

  • Carrying capacity is the maximum number of organisms an ecosystem can support.
  • Analogy: A farm that can only feed a limited number of people can be said to have reached its carrying capacity when any more people would result in there not being enough food to go around.
  • Carrying capacity can fluctuate due to resource availability.
    • Example: Rabbit population explosion in a wet year, followed by a decline in a drought year.

Limiting Factors

  • Limiting factors regulate ecosystem growth.
  • Example: Rain limiting grass growth, which in turn limits rabbit population.
  • Example: Food as a limiting factor for human population growth.

Impact of Water on Ecosystems

  • Too much water causes flooding, which can be both beneficial (e.g., Nile River replenishing land with nutrients) and catastrophic.
  • Droughts (too little water) can also be equally catastrophic.

Factors Affecting Ecosystem Stability

  • How biotic and abiotic factors affect ecosystem stability.
  • How organism diversity affects ecosystem stability.
  • How natural disasters (storms, fires) affect ecosystem stability.

Ecology 102, Section 2

  • Focus: Evaluating the effects of different factors on ecosystem stability and describing changes within an ecosystem.

Ecosystem Stability Components

  • Four main components:

    • Food Availability.
    • Water Availability.
    • Shelter Availability.
    • Biodiversity: A healthy ecosystem has high biodiversity; a weak ecosystem has low biodiversity.

  • Availability of these components affects an ecosystem's ability to withstand changes.

Ecosystem Succession

  • Succession: When something takes over after a disturbance.
  • Analogy: A king dying, and someone succeeding him to the throne.

Primary Succession

  • Occurs in areas where there is no soil.
  • Example: Pahoehoe lava in Hawaii. Over time, pioneer species colonize the cooled lava.
  • Pioneer species: The first organisms to inhabit an area without soil. Example: Lichen.
  • Lichens break down rock into small particles, which, along with organic materials, creates soil.
  • Primary succession is a initial process, with minimal initial growth beyond mosses and lichens until enough soil accumulates for diverse organisms.

Secondary Succession

  • Occurs in areas containing soil.
  • Example: Area after a forest fire. Grasses and other small plants start to grow on the soil.
  • Usually due to a natural phenomenon like fire or floods.

Impact of Natural Disasters

  • Hurricanes, tornadoes, fires, and earthquakes can cause serious damage to ecosystems.
  • Ecosystem Recovery: Over time, ecosystems can recover to their original state through succession.

Conclusion:

  • Availability of biotic and abiotic factors creates stability in ecosystems.
  • Changes in resource availability lead to changes in ecosystems.
  • Primary and secondary succession are common types of major ecosystem changes.