VCE Environmental Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Trophic level

A feeding position in a food chain, such as producer, primary consumer or secondary consumer. Organisms at the same level occupy similar roles regardless of species identity.

Ecological efficiency

The percentage of energy at one trophic level that is transferred to the next. It is typically about ten percent, with the remainder lost to respiration, egestion and uneaten biomass.

Net primary productivity

The energy or biomass fixed by producers that remains after their own respiration. Calculated as gross primary productivity minus producer respiration, usually expressed per unit area per year.

Nitrogen fixation

Conversion of atmospheric nitrogen gas into ammonia or ammonium compounds. Performed by bacteria such as Rhizobium in root nodules, by free-living soil bacteria, and by lightning-driven reactions.

Nitrification

Oxidation of ammonium to nitrite and then nitrate by soil bacteria. Nitrate is the form most readily taken up by plant roots, but it leaches easily from soil.

Denitrification

Reduction of nitrate to nitrogen gas by bacteria in waterlogged, low-oxygen soils. This returns nitrogen to the atmosphere and removes bioavailable nitrogen from the ecosystem.

Primary succession

Colonisation of a new substrate that lacks soil, such as bare rock, lava flows or retreating glacier deposits. Pioneer species such as lichens begin soil formation.

Carrying capacity

The maximum population size an environment can sustain indefinitely given available food, water, space and other resources. Represented by K in logistic population growth models.

Greenhouse gas

A gas that absorbs and re-emits longwave infrared radiation from Earth. Examples include carbon dioxide, methane, nitrous oxide, water vapour and chlorofluorocarbons.

Global warming potential

A measure of the heat trapped by a gas over a set period relative to carbon dioxide. Methane is roughly thirty times and nitrous oxide roughly three hundred times carbon dioxide over one century.

Ozone depletion

Thinning of the stratospheric ozone layer caused mainly by chlorine and bromine radicals from chlorofluorocarbons and halons. It increases ultraviolet radiation reaching Earth's surface.

Acid deposition

Sulfur dioxide and nitrogen oxides react with water vapour to form sulfuric and nitric acids, which fall as rain, snow or dry particles. It acidifies soils and lakes and damages vegetation.

Eutrophication

Nutrient enrichment of water bodies, usually by nitrogen and phosphorus, causing algal blooms, decomposition and oxygen depletion that can kill aquatic animals.

Biomagnification

Increasing concentration of a persistent, fat-soluble pollutant at each higher trophic level. Top predators such as raptors and large fish accumulate the highest concentrations.

Particulate matter

Suspended solid and liquid particles in air. PM2.5 particles are more harmful than PM10 because they penetrate deep into the lungs and enter the bloodstream.

Indicator species

An organism whose presence, absence or abundance signals environmental conditions. Lichens indicate sulfur dioxide pollution, and certain macroinvertebrates indicate water quality.

Species richness

The number of different species present in a defined area or community. It is a simple count and does not account for how evenly individuals are distributed among species.

Species evenness

The relative abundance of individuals among the species present in a community. High evenness means species are represented by similar numbers of individuals.

Habitat fragmentation

Splitting of continuous habitat into smaller, isolated patches, often by land clearing or roads. It increases edge effects and reduces gene flow between populations.

Edge effect

Altered conditions along the boundary of a habitat patch, such as more light, wind and predators. These changes can favour different species and degrade interior habitat.

In-situ conservation

Protecting species within their natural habitat through reserves, corridors, fire management and pest control. It preserves ecological interactions that off-site approaches cannot maintain.

Ex-situ conservation

Conservation of species outside their natural habitat, including seed banks, botanic gardens, zoos and captive breeding programs. It is often a backup for critically threatened species.

Fire regime

The characteristic pattern of fire in an ecosystem, described by frequency, intensity, season and patchiness. Many Australian species depend on particular regimes for regeneration.

Keystone species

A species whose influence on community structure is disproportionate to its abundance. Removing it can trigger cascading changes affecting many other species.

Ecological footprint

The area of productive land and water required to supply a population's resources and absorb its wastes. Expressed in global hectares and compared with available biocapacity.

Biocapacity

The capacity of a defined area's ecosystems to produce renewable resources and absorb wastes. Comparing it with ecological footprint shows whether a region runs a deficit.

Overshoot

The condition where demand on resources exceeds what ecosystems can regenerate. It is maintained temporarily by depleting natural capital such as forests, soils and fish stocks.

Life cycle assessment

A structured method to quantify environmental impacts of a product across its whole life, from raw material extraction through manufacture, use and disposal.

Mitigation

Actions that reduce the causes of climate change, such as cutting greenhouse gas emissions, improving energy efficiency and enhancing carbon sinks through reforestation.

Adaptation

Actions that reduce vulnerability to climate change impacts, such as sea walls, drought-tolerant crops, changed planting times and early-warning systems for extreme events.

Renewable energy

Energy from sources naturally replenished on human timescales, including solar, wind, hydro, geothermal, tidal and biomass. Their environmental impacts differ in land use and habitat change.

Environmental impact assessment

A formal process predicting the environmental effects of a proposed development before approval. It informs decision-making and often requires public consultation and mitigation measures.