Environmental Factors in Ecosystems

Environmental Limiting Factors

• Abiotic factors are non-living components of an environment that can limit population growth

  • Terrestrial factors include:
    • Climate: Temperature, humidity, wind, cloud cover, sunlight
    • Soil: Thickness, structure, porosity, pH, nutrient content, salinity
    • Area size: Space available
  • Aquatic factors include:
    • Salinity: Salt concentration
    • Turbidity: Water clarity
    • Depth: Distance from the water surface
    • Light: Availability of sunlight
    • Temperature: Water temperature
    • Oxygen: Dissolved oxygen levels
    • Currents: Water movement
    • pH: Acidity or alkalinity of water

• Biotic factors are living components of an environment that can limit population growth

  • Predator-Prey Interactions:
    • Predators consume prey, influencing prey population size
    • Typically, more prey than predators exist due to energy transfer limitations
  • Competition: Organisms compete for resources such as food, nesting sites, and water
    • Competition can restrict organisms to their realized niche, which is smaller than their potential fundamental niche.
  • Symbiosis: Relationships where at least one species benefits
    • Mutualism: Both species benefit
    • Commensalism: One species benefits, the other is unaffected
    • Parasitism: One species benefits at the expense of the other
  • Disease: Pathogens (disease-causing agents) can damage or kill their hosts, impacting population size

Biodiversity Measurements

• Species Richness: Number of different species present in an ecosystem

  • Standard species richness is the number of species per unit area.
  • Frequency tables can be used to quickly assess species richness in a particular area.
  • Limitations include not identifying the species or indicating ecosystem health.

• Relative Species Abundance: Proportion of one species compared to the total number of all species in an area

  • Can be hard to use if species are difficult to distinguish
  • Only provides information about a single target species

• Percentage Cover: Estimate of the proportion of an area covered by an organism

  • Measures the contribution and influence of each species in an area
  • Types of percentage cover include basal, ground, leaf, and canopy cover

• Species Evenness: Relative abundance of species compared to the total number of all species, indicating how evenly distributed species are

  • Can be measured using percentage cover or the Shannon-Wiener Index.
  • The Shannon-Wiener Index incorporates species richness and the relative abundance of each species into a single value.

Explore the various abiotic and biotic limiting factors that affect population growth in ecosystems. From climate and soil composition to predator-prey dynamics, this quiz covers essential concepts that influence living organisms in both terrestrial and aquatic environments.