Lecture 8

• Biosphere: the total area on Earth where living things are found
• Biome: a portion of the biosphere characterised by a distinct climate and particular assemblage of plants and animals adapted to it
• Ecosystem: a specific portion of a biome consisting of the biotic and abiotic environmental components that interact
• Community: all the populations living and interacting in an area. Represent the 'living' portion of the ecosystem
• Population: a group of individuals of the same species living and interacting in the same region
• Individual: a single member of the population
• Ecosystem functions:

  • how species interact
  • the flow of energy and nutrients
  • how species use resources
  • how many trophic levels exist
• Ecosystem Services:

  • Provisioning - providing food, water, fuel
  • Regulating - flood control, climate regulation
  • Supporting - carbon storage, nutrient cycling
  • Cultural - recreation, cultural benefits
• Example - Marine Ecosystem Services:

  • Climate and Atmosphere regulation
  • Commercial fishing
  • Threatened and Endangered species
  • Recreational activities
  • Subsistence harvest
  • Marine and coastal habitats
• Solar radiation is the principal source of energy that drives ecological productivity

  • Autotrophs: capable of photosynthesis
  • Heterotrophs: must feed on biomass produced by others
• Trophic levels:

  • Primary producers (autotrophs) - plants and photosynthetic bacteria
  • Secondary producers - feed on plants
  • Tertiary producers - feed on herbivores
  • Quaternary producers - feed at the apex of the food web
• Apex predator: top-level predator with no natural predator of their own; reside at the top of the food chain
• Habitat: the physical environment where a species typically lives
• Niche: the role a species plays in its ecosystem

  • not only habitat requirements but also how it acquires energy and nutrients
  • how it interacts with other species and non-biotic parts of the ecosystem
• Habitat and niche are important parts of biosphere integrity
• Keystone species: a species that has a disproportionally large effect on its environment compared to its relative abundance e.g. Pacific Salmon

  • when a keystone species is removed from a system, the ecosystem may change drastically even if it was a small part - e.g. Wolves in Yellowstone National Park - Trophic cascade
• Trophic Cascade: when the impact of a predator on its prey affects one or more trophic levels

  • when the apex predator is removed - there is a lack of pop. control at the next trophic level - affects the pops. at the level below
  • must occur across a min. of 3 trophic levels
  • can also happen from bottom up
• Every piece of an ecosystem is interdependent - these connections create ecosystem complexity
• How does biodiversity enhance ecosystem resilience?

  • genetic diversity
  • affects ecosystem functions and services
• Control variables:

  • Genetic diversity (extinction rate) - 100-1000 E/MSY
  • Functional diversity (biological intactness index BII) - 84%
• Planetary boundary:

  • Genetic diversity - <10 extinctions per million species per year (E/MSY) but with a goal of 1 E/MSY
  • Functional diversity - Maintain BII at 90% or above
• Are we in the 6th mass extinction?

  • increased % of extinction for mammals and amphibians
  • habitats destroyed, climate change, highest atmospheric CO2 concentration in 800,000 years
  • invasive species
  • invertebrates have declined by 45%
• What is driving Biodiversity loss?

  1. Changes in land and sea use
  2. Climate change
  3. Pollution
  4. Exploitation of natural resources
  5. Invasive species
• Kunming-Montreal Global Biodiversity Framework (2022-):

  • one major target of the new agreement is to ensure at least 30% of terrestrial, inland water, and of coastal and marine areas are effectively conserved and managed by 2030 - the 30 * 30 goal
  • critical that Indigenous land rights, stewardship and leadership in conservation is included