Understanding Biotic and Abiotic Environments

• An environment involves the interrelationship between living (biotic) and non-living (abiotic) components.

Biotic components

• Flora (plants).
• Fauna (animals).
• Fungi & bacteria.

Abiotic components

• Temperature.
• Rainfall.
• Humidity.
• Wind speed & direction.
• Non-living parts of soil (sand, clay, rock).

Types of Environments

• Natural environments occur naturally, for example, forests, deserts, and coral reefs.
• Human environments are built or altered by humans, for example, cities, towns, and farmlands.
• An ecosystem is defined as the living organisms within a community & the non-living components of the environment in which they live, linked through the flow of energy in food chains and food webs.
• Each food chain represents one possible path for energy and nutrients through an ecosystem, consisting of producers and consumers.
• Producers are organisms (plants) that convert the Sun's energy into food via photosynthesis, forming simple sugars.
• Consumers are animals that eat plants or other animals to obtain energy.

Components of an Environment

• Individual: A single member of a species.
• Population: Individuals of the same species in the same area at the same time.
• Community: Multiple populations (different species) living and interacting in the same area.
• Ecosystem: The interaction between a community and the non-living (abiotic) parts of the environment.
• Biome: The largest environmental unit other than Earth, defined by landscapes with similar climates and vegetation types (eight major global biomes).

Australian Biomes & Climate Zones

• Australia has five terrestrial biomes defined by major vegetation type.
• Mountain vegetation.
• Temperate forest (outside tropics).
• Grassland.
• Desert.
• Tropical forest (inside tropics).
• Climate (rainfall, temperature, humidity, sunlight hours) and soil type influence the types of plants that grow in an area, influencing the type of biome.

Processes in the Environment

• Earth has physical processes that help sustain life: hydrological (water) cycle, carbon cycle, and oxygen cycle.

Hydrological Cycle

• The hydrological cycle recycles water between sea, land, and atmosphere via evaporation, condensation, and precipitation.
• Evaporation (and transpiration from plants).
• Condensation.
• Precipitation (rain, hail, snow).
• Collection (run-off on land).
• Evaporation transforms into atmosphere as water vapour, condenses to form clouds, precipitates.

Carbon Cycle

• The geological carbon cycle is a long-term cycle occurring over hundreds to millions of years, resulting in bulk carbon being locked in rocks/sediments as fossil fuels.
• The biological carbon cycle is a short-term cycle over days/weeks/months/years involving cycling of carbon through photosynthesis and cellular metabolism.
• Carbon can cycle through land, oceans, and the atmosphere over short and long terms; stored long-term in trunks/branches of trees.
• When these organisms die, carbon returns to the atmosphere as carbon dioxide; carbon is stored in carbon 'sinks' (e.g. organic matter, rocks, and dissolved carbon dioxide in water).
• Fire consumes biomass and organic matter, producing carbon dioxide, methane, carbon monoxide & smoke.

Increase in Deforestation

• Increases in deforestation and carbon dioxide enhance the greenhouse effect.

Oxygen Cycle

• Oxygen is essential for life on earth
• Oxygen exists in three reservoirs.
• Atmosphere (0.49%) as gases O2 and O3, and in compounds such as H2O and CO2.
• Lithosphere (99.5%).
• Living organisms (0.01%).
• The oxygen cycle is heavily influenced by processes in the biosphere and atmosphere.
• Biosphere: Photosynthesis releases oxygen, and respiration absorbs oxygen.
• Atmosphere: Oxygen is formed when UV light converts water to oxygen + hydrogen through photolysis.
• Oxygen is removed from the atmosphere via cellular respiration, organism decay, and weathering.

Attitudes to the Environment

• Ecosystem services are threatened by degradation caused by humans.
• Clean air, plant pollination, fertile soil, filtering water, providing food, and purifying air.

The Four S's of Ecosystem Services

• Ecosystem services are classified by the products they provide and the functions they perform.
• Sources/Provisioning Services: Natural products used/converted by humans (e.g., mineral deposits like coal → fuel, iron ore → manufacturing, timber etc.).
• Sinks/Regulating Services: Natural processes that absorb waste (e.g., micro-organisms in oceans break down oil spills).
• Services/Supporting Services: Removing impurities from the environment (e.g., wetlands take out sediment, forests take out CO2).
• Spirituality: Deep connection to the land, experience of spending time in nature, and activities like surfing/bushwalking (cultural services).

World Views

• Human-centred:
  • Egocentric: The individual believes they are the most important creature, and everything is important to the extent that it supports their lifestyle.
  • Anthropocentric: Humans are the most important species, in charge of the natural world.
• Earth-centred:
  • Ecocentric: Efforts should minimise impact and preserve biodiversity.
  • Biocentric: The earths resources should be used sustainably, all species have an equal right to exist.

Challenges to Sustainability

• Sustainability: The ongoing capacity of the environment to support the lives of all living things into the future.
• Sustainable use of resources (e.g., fossil fuels, forests, oceans) conserves resources to meet present needs without compromising the future.
• When resources are used sustainably, environmental quality is maintained, and resources continue to provide for future generations.

The Fishing Industry

• Fish provides over 15% of animal protein eaten by 3 billion people.
• ≥ ½ of species have no potential for increased production.
• ≥ ½ are described as being overfished.
• Unsustainable levels of fishing are driven by food demands of an increasing population + modern fishing techniques (e.g. spotter planes, fishing in deeper waters, dragging huge nets across ocean floor).
• Some countries have fisheries management plans (quotas on the number of fish).

Loss of Biodiversity

• Biodiversity: Variety of living organisms on the planet, measured by the number of species present in an ecosystem/region.
• Loss of biodiversity affects the natural environment and human beings, causing a decline in ecosystem services.
• Causes of the Loss of Biodiversity:
• The use of Earth's resources is pushing many species to extinction.
  • Habitat change: E.g., deforestation, removal of vegetation, environments get split by development, pollution from human activities.
  • Over-exploitation of resources (e.g., fresh water), impacting biodiversity (food chains + balances).
  • Pollution of land, water, and air: Water, air, and land pollution interact, and plastic does not break down.
  • Spread of invasive species: Exotic species introduced into the environment (e.g., rabbits, cane toads, Indian mynah, cats, mice).
  • Climate change brought about by human activity: Changes in rainfall and temperature patterns, agricultural regions become drier, pest species become more prevalent, and disease spreads more easily.