WBCHSE HS ENVS flashcards

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

Ecological niche

The functional role of a species in its community, including resource use, tolerance ranges and activity timing. No two species can occupy an identical niche indefinitely without competitive exclusion.

Logistic growth equation

dN/dt = rN(K − N)/K, where N is population size, r the intrinsic growth rate and K the carrying capacity. Growth slows as N approaches K, producing an S-shaped curve.

Ten percent law

Lindeman's rule that only about 10% of energy at one trophic level is transferred to the next. The rest is lost as heat, respiration and unassimilated matter, limiting food chain length.

Carrying capacity

The maximum population size of a species that an environment can sustain indefinitely given available food, water, space and other resources. Symbol K in the logistic growth model.

Renewable versus non-renewable resources

Renewable resources regenerate within a human lifetime (solar, wind, biomass, soil fertility); non-renewable resources form over geological time (coal, petroleum, minerals) and are depleted by use.

Contour ploughing

Ploughing along the contour lines of a slope rather than up and down it. It slows runoff, traps water and reduces sheet and rill erosion on cultivated hillsides.

Rainwater harvesting

Collection and storage of rainwater from roofs or catchments for later use or groundwater recharge. It reduces dependence on groundwater and cuts urban runoff and flooding.

Watershed management

Integrated planning of land, water and vegetation within a drainage basin to conserve soil and water, reduce erosion and sustain yields. Measures include check dams, afforestation and contour bunds.

Net primary productivity

The organic matter produced by plants that remains after their own respiration, equal to gross primary productivity minus respiration. It is the energy available to consumers and decomposers.

Inverted biomass pyramid

A pyramid in which consumer biomass exceeds producer biomass at a given moment, as when many insects feed on one large tree. Energy pyramids are never inverted.

Ecosystem services

Benefits people obtain from ecosystems, grouped as provisioning (food, water), regulating (climate, flood control), cultural (recreation) and supporting (nutrient cycling, soil formation).

Ecological resilience

The capacity of an ecosystem to absorb disturbance and return to its original structure and function. It differs from resistance, which is the ability to remain unchanged during disturbance.

Biodiversity hotspot

A region with exceptional endemic species and severe habitat loss. India contains four: the Himalaya, Indo-Burma, Western Ghats–Sri Lanka and Sundaland (Nicobar Islands).

IUCN Red List categories

A global system ranking extinction risk: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient and Not Evaluated.

Keystone species

A species whose influence on community structure is disproportionately large relative to its abundance. Removing it triggers cascading changes, as with sea otters controlling sea urchins.

In-situ versus ex-situ conservation

In-situ conservation protects species in their natural habitat (national parks, sanctuaries, sacred groves); ex-situ conservation maintains them outside it (zoos, seed banks, botanical gardens).

Biochemical oxygen demand

The oxygen consumed by microorganisms decomposing organic matter in a water sample over five days at 20°C. High BOD signals organic pollution and low dissolved oxygen.

Electrostatic precipitator

An air pollution control device that charges particles and collects them on oppositely charged plates. It removes fine particulate matter with high efficiency and low pressure drop.

Eutrophication

Nutrient enrichment of water, usually by nitrogen and phosphorus, causing algal blooms, oxygen depletion and fish kills. Control requires nutrient removal and buffer strips.

Polluter pays principle

The principle that those who cause pollution should bear the cost of managing it, including prevention, control and clean-up. It underpins environmental taxes and liability rules.

Waste hierarchy

The preferred order of waste management: prevention first, then reuse, recycling, energy recovery, and safe disposal last. It prioritises avoiding waste over treating it after generation.

Extended producer responsibility

A policy making producers responsible for the take-back and end-of-life management of their products and packaging. It shifts disposal costs upstream and encourages recyclable design.

Sanitary landfill

An engineered disposal site with a liner, leachate collection, gas venting and daily soil cover. It isolates waste and prevents groundwater contamination, unlike open dumping.

Circular economy

An economic model that designs out waste and pollution, keeps materials in use and regenerates natural systems, replacing the linear take-make-dispose pattern with closed material loops.

Global warming potential

The heat trapped by a greenhouse gas over a set period relative to carbon dioxide. GWP-100 for methane is about 28, meaning it traps 28 times more heat than CO2.

Montreal Protocol

The 1987 international treaty that phased out ozone-depleting substances such as CFCs and halons. Its Kigali Amendment later added a phase-down of hydrofluorocarbons.

Paris Agreement

The 2015 climate treaty under the UNFCCC in which countries submit nationally determined contributions to hold warming well below 2°C, pursuing efforts to limit it to 1.5°C.

Mitigation versus adaptation

Mitigation reduces greenhouse gas emissions or enhances sinks to slow climate change. Adaptation reduces vulnerability to climate impacts through measures such as embankments and drought-resistant crops.

Brundtland definition

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs, as stated in the 1987 Brundtland Report.

Precautionary principle

Where there is a threat of serious or irreversible environmental harm, lack of full scientific certainty should not delay cost-effective measures to prevent it. It justifies early regulation.

Environmental Impact Assessment

A formal process predicting the environmental effects of a proposed project before approval. Steps include screening, scoping, baseline study, impact prediction, mitigation and public hearing.

Biomagnification

The increase in concentration of a persistent substance, such as DDT or mercury, at successive trophic levels. Top predators accumulate the highest concentrations, harming health.

Minamata disease

A neurological disorder caused by methylmercury poisoning from contaminated fish, first documented in Minamata, Japan. It causes numbness, vision loss, tremors and birth defects.

Disaster risk equation

Disaster risk equals hazard multiplied by vulnerability divided by capacity. Reducing vulnerability or strengthening coping capacity lowers risk from the same hazard.

Sendai Framework

The 2015–2030 global agreement on disaster risk reduction with four priorities, including understanding risk and strengthening governance. It succeeded the Hyogo Framework.

Disaster management cycle

The recurring sequence of mitigation and prevention, preparedness, response and relief, recovery, and rehabilitation, which loops back to mitigation after each disaster.

Quadrat method

A vegetation sampling technique using randomly placed square plots of known area. Frequency is the percentage of quadrats containing a species; density is individuals per unit area.

Bioindicator species

An organism whose presence, abundance or condition reveals environmental quality. Lichens indicate sulphur dioxide levels; diatoms and mayflies indicate water pollution.

Winkler titration

A standard method for measuring dissolved oxygen in water. Reagents fix oxygen, and liberated iodine is titrated with thiosulfate to calculate oxygen concentration.