Ecosystems and Environmental Change

Dr chase lecture 12/09/25

Ecosystem Components

  • Ecosystems consist of:

    • Abiotic components: Non-living elements

    • Examples include:

      • Sunlight

      • Inorganic nutrients

      • Soil type

      • Water

      • Temperature

      • Wind

    • Biotic components: Living organisms

    • Include various populations of species forming a community

Classification of Organisms in Ecosystems

  • Organisms in ecosystems can be categorized based on their food sources:

    • Autotrophs (self eaters):

    • Require energy source and inorganic nutrients to produce organic nutrients

    • Makeup the ecosystem’s producers

    • Examples: Green plants and algae

      • Carry out photosynthesis, creating organic nutrients

    • Heterotrophs (other feeders):

    • Acquire organic nutrients from external sources

    • Include:

      • Herbivores: Primary consumers feeding on plants/algae

      • Carnivores: Secondary consumers that feed on herbivores

      • Omnivores: Consumers that feed on both plants and animals

    • Decomposers:

    • Break down nonliving organic matter

    • Examples include bacteria and fungi, which recycle nutrients back into the ecosystem

    • Detritivores: Organisms feeding on detritus (partially decomposed matter)

Energy Flow in Ecosystems

  • Every ecosystem is characterized by:

    • Energy flow:

    • Energy enters when producers absorb solar energy

    • Ecosystems need a continual supply of solar energy for plants to thrive

    • Chemical cycling:

    • Producers utilize inorganic nutrients from the environment

    • After consumption, decomposers return inorganic nutrients back to the soil

Energy Transfer and Food Webs

  • Energy transfer is not 100% efficient; energy loses include:

    • Heat loss

    • Cellular respiration fuels and waste

  • Energy flow across ecosystem components is commonly illustrated as:

    • Food Webs

    • Grazing Food Webs: Characterized by herbivores feeding on leaves and fruit

    • Detrital Food Webs: Begins with detritus feeding organisms

    • Food Chains: Simplistic linear representation of energy flow

    • Each feeding level is referred to as a Trophic Level

      • Primary producers: First trophic level

      • Primary consumers: Second trophic level

      • Secondary and higher level consumers for carnivores

Ecological Pyramid

  • Represents the number of organisms at each trophic level multiplied by their weight; termed biomass

  • Biomass example:

    • A few large oaks may have a greater biomass than numerous small herbivores

    • Exception: In certain aquatic ecosystems, herbivores can surpass producers in biomass

Global Biogeochemical Cycles

  • Pathways through which chemical elements move between biotic and abiotic components

  • Reservoirs: Sources like fossilized remains and rocks, inaccessible to producers

  • Exchange Pools: Source from which organisms derive chemicals (e.g., atmosphere, soil)

  • Biotic Community: Path where chemicals flow along food chains

  • Types of biogeochemical cycles:

    • Gaseous Cycles: Elements exchanged with atmosphere

    • Sedimentary Cycles: Elements cycled through soil (excluding water)

The Water Cycle

  • Describes how water transitions between states:

    • Evaporation: Liquid to gas

    • Condensation: Gas to liquid

    • Precipitation brings water back to the surface

  • Water travels through:

    • Rain falling into various bodies (oceans, lakes, soil)

    • Recycles back through evaporation, transpiration, and groundwater

  • Aquifers: Underlying rock layers store groundwater, recharge through rainfall

Carbon Cycle

  • Cycle that demonstrates how carbon moves through photosynthesis and respiration:

    • Plants absorb CO2 from the air and incorporate it into organic matter

    • Cellular respiration in heterotrophs recycles carbon dioxide back to the atmosphere

    • Fossil fuels formed from decayed organic matter act as carbon reservoirs

Climate Change and its Implications

  • Human activity has accelerated climate change through:

    • Increased carbon emissions from burning fossil fuels

    • Deforestation

  • Resulting environmental impacts:

    • Rising temperatures, altered weather patterns leading to severe weather events

    • Rising sea levels affecting coastal cities

Discussion on Genetic Principles pedigree inheritance chart rules

  • Overview of pedigrees and Punnett squares relevant to trait inheritance:

    • Dominant vs. Recessive Traits: Observing if traits skip generations helps determine inheritance patterns

    • Autosomal vs. Sex-linked Traits: Differences in inheritance between genders based on sex chromosomes

Conclusions and Further Studies

  • Understanding ecosystems, energy flow, chemical cycles, and genetic principles are vital for comprehending environmental dynamics and challenges.