A consumer that feeds on producers and so occupies the second trophic level, such as a herbivore.
101 of the ESS glossary’s terms, each with the part of the syllabus where you first meet it.
The probability of obtaining a result at least as extreme as the one observed if the null hypothesis were true; values below 0.05 are usually taken as significant.
A protected area that exists in law but lacks the funding, staff or enforcement to protect it in practice, so poaching, logging or settlement continue.
A local person, often without a university degree, trained to collect, identify and record specimens and field data so that biodiversity can be surveyed where few professional scientists work.
A relationship in which one organism, the parasite, lives on or in another, the host, and feeds from it, harming the host, usually without killing it quickly.
The underlying rock, or deposited material such as river sediment, wind-blown silt or volcanic ash, whose weathering supplies most of a soil's mineral matter.
The international climate agreement adopted at COP21 in 2015, in which almost every country agreed to keep warming well below 2 °C and to set its own emissions targets.
Tiny solid particles and liquid droplets suspended in the air, such as soot, dust, smoke and sulfate or nitrate particles, classified by diameter as PM10 and PM2.5.
A farming system based on raising livestock, such as cattle, sheep or goats, usually grazing grassland, for meat, milk, wool or hides.
A microorganism or virus that causes disease in its host, such as a bacterium, virus, fungus or protist.
Schemes in which users or beneficiaries of an ecosystem service pay the landowners or communities who manage the land that provides it, in return for protecting or restoring it.
Levelling out the highest peaks in electricity demand, for example by supplying stored energy or shifting demand to other times, so that less generating capacity is needed.
A correlation coefficient, r, measuring how closely two continuous variables follow a straight-line relationship, from −1 to +1.
A waterlogged soil made of partly decomposed plant material that builds up because anaerobic conditions slow decomposition; a large carbon store that becomes a source when drained or burned.
A country's gross domestic product divided by its population, giving average output per person; a rough measure of living standards that ignores inequality.
The size of a change expressed as a percentage of the original value, calculated as (new value − original value) ÷ original value × 100; a negative result shows a decrease.
An estimate of the percentage of the area within a quadrat that is covered by a particular species, seen from above.
The percentage of sampling units, such as squares within a quadrat or whole quadrats, in which a species is present.
The movement of water down through the soil and into the rock below, under the influence of gravity.
A system of agricultural and settlement design that imitates the structure and relationships of natural ecosystems to produce food sustainably with few external inputs.
Ground that remains at or below 0 °C for at least two consecutive years, found beneath tundra and boreal forest, which stores large amounts of organic carbon.
Secondary pollutants (PANs) formed in photochemical smog from volatile organic compounds and nitrogen dioxide, which irritate the eyes and lungs and damage plants.
A carbon-based chemical, such as DDT or PCBs, that resists breakdown, dissolves in fats, travels long distances and builds up in food chains.
The way an individual views and understands a situation, based on a mix of personal and collective assumptions, values and beliefs.
A chemical or biological substance used to kill or control organisms regarded as pests, including insects (insecticides), weeds (herbicides) and fungi (fungicides).
A scale from 0 to 14 that measures how acidic or alkaline a solution or soil is; 7 is neutral, lower values are acidic and higher values alkaline.
A loss of synchrony between the timing of linked life-cycle events, such as a food peak and the demand of its consumers, caused by species responding differently to environmental change.
A negatively charged ion of phosphorus and oxygen (PO₄³⁻); a plant nutrient, often limiting in fresh water, that enters water in sewage, detergents, manure and eroded soil.
An autotroph that uses light energy to make organic compounds by photosynthesis, such as a green plant, alga or cyanobacterium.
A brownish haze of secondary pollutants, mainly tropospheric ozone and peroxyacyl nitrates, formed when sunlight drives reactions between nitrogen oxides and volatile organic compounds.
The process by which producers use light energy to convert carbon dioxide and water into glucose and oxygen, transforming light energy into chemical energy.
A shortage of water caused by the actual amount of freshwater available being too small to meet the demands of a population, typical of arid regions.
Microscopic photosynthetic organisms, such as diatoms and cyanobacteria, that drift in the surface waters of oceans, seas and fresh water and form the base of most aquatic food webs.
A circular graph divided into sectors whose angles are proportional to the share of each part of a whole, used to show proportions such as land use or energy sources.
The three dimensions on which sustainability rests: environmental, social and economic, each of which must be maintained for a practice or system to be sustainable.
A small-scale trial of an investigation's method, carried out before the main data collection, to test its practicality and identify changes needed.
The first community to become established on a newly exposed or disturbed surface at the start of succession, made up of pioneer species.
A species that is first to colonise bare ground or rock, able to tolerate harsh conditions such as lack of soil, nutrients and water, and often an r-strategist.
A container sunk level with the ground surface so that small animals walking across the ground fall in and can be counted.
A stable community that develops when human activity, such as burning, grazing or mowing, stops or diverts succession before the climatic climax is reached.
A model identifying nine Earth system processes that have kept the planet stable during the Holocene, with a limit to human disturbance of each; crossing a limit raises the risk of abrupt, irreversible change.
A mostly plant-based reference diet published by the EAT-Lancet Commission in 2019, designed to be healthy and to feed about 10 billion people within planetary boundaries.
Organisms that live in water and drift with currents because they cannot swim strongly against them, including photosynthetic phytoplankton and consuming zooplankton.
The practice of designing products with an artificially limited useful life, for example by making them hard to repair or quickly outdated, so that they must be replaced sooner.
A diet made up mostly or entirely of foods from plants, such as grains, vegetables, fruit, legumes and nuts, with little or no animal produce.
A food product made from plant proteins, such as soy, pea or wheat, processed to resemble meat in taste, texture and appearance.
The accumulation of plastic objects and particles in the environment in amounts that harm wildlife, habitats or people.
The final phase of an S-shaped growth curve, in which births roughly equal deaths and the population fluctuates around the carrying capacity.
Fine particulate matter with a diameter of 2.5 micrometres or less, small enough to reach the deepest parts of the lungs and enter the bloodstream.
Particulate matter with a diameter of 10 micrometres or less, which can be inhaled into the nose, throat and upper airways.
The illegal hunting, killing or capture of wild animals, or collection of wild plants, usually for sale, such as killing elephants for ivory or rhinoceroses for their horns.
Pollution released into the environment from a single, clearly identifiable location, such as a discharge pipe, sewage outfall or chimney, which makes it easier to monitor and regulate.
The cell of atmospheric circulation between about 60° latitude and the pole, in which cold, dense air sinks at the pole and flows towards lower latitudes at the surface.
A cloud of ice or nitric acid particles that forms in the polar stratosphere at about −80 °C or colder; reactions on its surfaces release chlorine that destroys ozone when sunlight returns in spring.
A large ring of strong winds that circles a pole in the stratosphere during winter, isolating very cold air inside it and allowing polar stratospheric clouds to form.
An uneven distribution of electric charge across a molecule; in water the oxygen atom is slightly negative and the hydrogen atoms slightly positive.
The identification and counting of pollen grains preserved in layers of peat or lake sediment, used to reconstruct past vegetation and the changes of succession.
A substance or form of energy, such as heat, that harms living things or the environment when it is added faster than it can be dispersed, broken down or stored.
The principle that whoever causes pollution should bear the costs of preventing, managing and cleaning it up, rather than passing them on to society or the environment.
The addition of a substance or form of energy to the environment at a rate faster than it can be made harmless by dispersal, breakdown, recycling or storage, causing harm to living things.
A model matching management strategies to three stages of pollution: changing the human activity that produces a pollutant, controlling its release, and cleaning up and restoring ecosystems.
A group of persistent, fat-soluble industrial chemicals once used in electrical equipment, which biomagnify in food chains and harm the immune and reproductive systems of top predators.
The growing of several crop species together on the same land at the same time, such as intercropping, which increases diversity and ground cover.
A group of organisms of the same species living in the same area at the same time, which are capable of interbreeding.
The number of individuals of a species per unit area or per unit volume.
The changes in the size, density and structure of populations over time, and the birth, death and migration processes that cause them.
The percentage change in the size of a population over a year, combining natural increase and net migration.
The tendency of a population to keep growing for decades after fertility falls to replacement level or below, because a large share of its people are young adults of, or approaching, childbearing age.
A deliberate government measure intended to change the size, growth rate, age structure or distribution of a population, directly through births or migration or indirectly through social and economic policy.
A calculation of the future size and age structure of a population based on stated assumptions about future fertility, mortality and migration; a scenario rather than a prediction.
A feedback loop in which a disturbance leads to amplification of that disturbance, destabilising a system and driving it away from its equilibrium.
An approach to decisions under uncertainty: where an activity threatens serious or irreversible harm, lack of full scientific certainty is not a reason to postpone preventive action.
The slow change in the direction in which the Earth’s axis points, which shifts the season in which the Earth is closest to the Sun over a cycle of roughly 21,000–26,000 years.
The transfer of water from the atmosphere to the Earth's surface as rain, snow, sleet, hail or drizzle.
The closeness of repeated measurements to one another, and the smallest division that a measuring instrument can resolve.
An interaction in which one animal, the predator, kills and eats another, the prey.
Regular, linked rises and falls in the populations of a predator and its prey, with the predator lagging behind the prey; an emergent property of their interaction.
A waste management strategy that stops waste being produced or released into the environment, by altering behaviour (such as reducing consumption) or by controlling release (such as safe disposal).
A consumer that feeds on producers and so occupies the second trophic level, such as a herbivore.
Data collected first-hand by the investigator for the investigation, for example by fieldwork, laboratory measurement or a survey.
Energy in the form in which it is found in nature before any human conversion, such as the chemical energy in coal, oil, gas and wood, or the energy in sunlight and wind.
A pollutant that is harmful in the form in which it is emitted directly from its source, such as carbon monoxide, sulfur dioxide or soot.
The rate of production of biomass by autotrophs using an external energy source and inorganic carbon, per unit area per unit time, such as kg C m⁻² yr⁻¹.
Succession on a newly formed surface with no soil and no previous community, such as new volcanic rock, a glacial moraine, wind-blown sand or freshly deposited silt.
The first, physical stage of sewage treatment, in which screens and settling tanks remove large objects, grit and settleable solids.
A population policy intended to raise the birth rate, for example through child benefits, tax incentives, paid parental leave, childcare or restrictions on contraception and abortion.
An organism, such as a plant, alga or photosynthetic bacterium, that makes its own organic compounds from inorganic substances and forms the first trophic level.
The sequence of stages a product passes through, from raw material extraction, through manufacture, distribution and use, to its end of life as waste or as recovered material.
An approach in which responsibility for reducing a product's environmental impact over its whole life cycle is shared by the manufacturer, the retailer and the user.
The rate at which biomass or energy is gained by an organism, trophic level or ecosystem, per unit area per unit time.
The legal or customary rights to own, use, exclude others from, and sell or transfer a resource.
A clearly defined area of land or sea that is legally recognised and managed for the long-term conservation of nature, such as a national park or nature reserve.
A later international agreement attached to a convention that adds specific, often quantified, commitments and becomes legally binding only on the states that ratify it, such as the Kyoto Protocol.
The quantity of a fossil fuel or mineral that geological and engineering data show, with reasonable certainty, can be extracted from known deposits under existing economic and technological conditions.
Ecosystem services that supply material products people obtain from ecosystems, such as food, freshwater, timber, fibre, fuel and medicines.
Indirect evidence of past climate preserved in natural records, such as ice cores, tree rings, pollen and sediments, used to reconstruct conditions from before instrumental measurements began.
A method of storing energy in which surplus electricity pumps water to a higher reservoir, and the water is later released through turbines to generate electricity at times of high demand.
Deliberately choosing respondents because they have particular knowledge or roles relevant to the research question, such as park managers or farmers.
The conditions that encourage people to leave a place (push factors, such as poverty or lack of services) and the real or perceived advantages that attract them elsewhere (pull factors, such as jobs).
An ecological pyramid showing the standing crop of biomass at each trophic level per unit area at one time, usually in g m⁻² of dry mass.
An ecological pyramid showing the energy flowing into each trophic level per unit area per unit time, usually in kJ m⁻² yr⁻¹; it is never inverted.
An ecological pyramid showing the number of individual organisms at each trophic level per unit area at one time.