MATSEC SEC Environmental Studies flashcards

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

Ecosystem

A functional unit in which a community of organisms interacts with its non-living environment, exchanging energy and cycling nutrients through connected food webs.

Trophic level

A feeding position in a food chain, such as producer, primary consumer or decomposer. Energy is lost as heat at each transfer between levels.

Ten percent rule

The ecological principle that only about ten percent of energy at one trophic level is transferred to the next, the rest being lost mainly as heat through respiration.

Carrying capacity (K)

The maximum population size of a species that a given habitat can sustain indefinitely, given available food, water, space and other limiting resources.

Limiting factor

Any resource or condition, such as light, water, nutrients or predation, that restricts the growth, abundance or distribution of a population.

Biotic potential

The maximum rate at which a population could grow under ideal conditions, with unlimited resources and no environmental resistance or predation pressure.

Habitat

The physical place where an organism lives, defined by its particular combination of climate, substrate, shelter and food resources needed for survival.

Ecological niche

The full role and position of a species in its ecosystem, including its habitat, food sources, activity timing and interactions with other species.

Biodiversity

The variety of life at three levels: genetic variation within species, the number of species, and the range of ecosystems and habitats present.

Endemic species

A species found naturally in one restricted area and nowhere else, making it especially vulnerable to local habitat loss, invasive species and climate change.

Keystone species

A species whose removal causes disproportionate change to the whole ecosystem, for example a predator controlling herbivore numbers or a beaver creating wetlands.

Succession

The gradual, directional change in species composition of a community over time, from pioneer species on bare ground towards a relatively stable climax community.

Nitrogen fixation

Conversion of atmospheric nitrogen gas into ammonia compounds by bacteria such as Rhizobium in root nodules, making nitrogen available to plants.

Eutrophication

Nutrient enrichment of water, usually by nitrates and phosphates, causing algal blooms, oxygen depletion and death of fish and other aquatic organisms.

Bioaccumulation

The build-up of a persistent substance, such as a heavy metal or pesticide, within an individual organism over its lifetime through uptake from food and environment.

Biomagnification

The increase in concentration of a persistent pollutant at each successive trophic level, so top predators carry the highest body burdens and greatest toxic risk.

Point source pollution

Pollution entering the environment from a single identifiable outlet, such as a factory pipe or sewage outfall, making it easier to monitor and regulate.

Non-point source pollution

Pollution from diffuse, unidentifiable origins such as agricultural runoff or urban stormwater, which is harder to measure and control than a single outlet.

Sustainable development

Development that meets present needs without compromising the ability of future generations to meet theirs, balancing economic, social and environmental objectives.

Renewable resource

A natural resource replenished by natural processes at a rate comparable to its use, such as solar energy, wind, timber and fish stocks under sustainable management.

Non-renewable resource

A resource formed over geological timescales, such as coal, oil, natural gas or mineral ores, whose stock is effectively fixed and depleted by extraction.

Ecological footprint

An estimate of the land and water area needed to supply a population's resources and absorb its wastes, expressed in global hectares.

Carbon sink

A reservoir, such as a forest, soil or ocean, that absorbs and stores more carbon than it releases, helping to slow the rise of atmospheric carbon dioxide.

Greenhouse effect

Warming of the lower atmosphere as gases such as carbon dioxide, methane and water vapour absorb outgoing infrared radiation and re-emit it towards the surface.

Acid rain

Rainfall made acidic by sulphur dioxide and nitrogen oxides from fossil fuel burning, which damages soils, freshwater life, forests and stone buildings.

Ozone depletion

Thinning of the stratospheric ozone layer by chlorine and bromine compounds such as CFCs, allowing more ultraviolet radiation to reach the Earth's surface.

EIA

Environmental Impact Assessment: a structured process predicting the environmental effects of a proposed project before approval, and proposing mitigation and monitoring measures.

Mitigation hierarchy

The ordered approach to impacts: avoid first, then minimise, then restore or rehabilitate, and only finally offset any residual unavoidable environmental damage.

Precautionary principle

The rule that lack of full scientific certainty should not delay cost-effective measures to prevent serious or irreversible environmental harm.

Polluter pays principle

The principle that those who cause pollution should bear the cost of managing it and preventing damage, rather than passing that cost to society.

Environmental indicator

A measurable variable, such as air quality index, water pH or species counts, used to summarise and track the state of an environmental system over time.

Habitat fragmentation

The breaking up of a continuous habitat into smaller, isolated patches, reducing gene flow, raising edge effects and increasing extinction risk for sensitive species.

Invasive species

A non-native species introduced outside its natural range that spreads rapidly, outcompetes native organisms and disrupts ecosystem function and local biodiversity.