Genetic changes that occur within the line of descent of a species. …
The belief that evolution and speciation occur over a long period of time through slow, progressive change. Contrast punctuated equilibrium. …
Relating to evolutionary development. Contrast ontogenetic. …
The study of the relationships between organisms; a branch of systematics. …
The idea that a species is the smallest recognizable group of individual organisms within which there is a parental pattern of ancestry and descent. Contrast biological species concept. …
The evolutionary history and line of descent of a species. …
The second highest category (of seven) in the scientific system of classification for organisms (taxonomy), below kingdom and above class. Each kingdom comprises more than one phylum, and each phylum comprises more than one class. For example, the phylum Mollusca includes slugs, snails, clams, squid. The phylum Chordata includes all of the ?higher? animals (including fish, amphibians, reptiles, bi…
Processes that are used to clean up pollution (including toxic materials in surface and groundwater, oil spills, and hazardous materials on or in the ground) and in large‐scale wastewater treatment facilities. Physical processes may include air stripping or filtration. Chemical treatment includes coagulation, chlorination, or ozonation. …
The inorganic surroundings that are necessary for life, such as air, water, soil, rock, and sunlight. …
Any non‐living (abiotic) factor, such as temperature, light, water, minerals, and climate, that influence an organism. …
The study of the world's oceans, particularly in terms of water masses and their motions. …
A form of land use planning, particularly in urban areas, which seeks to achieve a physically attractive environment by regulating the relationships between structures and their sites and surroundings. …
A measure of economic welfare that is more sophisticated than gross national product, and is based on three variables: percentage of the population which is literate, infant mortality rate, and average life expectancy after the age of one. …
The study of matter and energy, and their interactions. …
External appearance: an old fashioned term to describe the topography and other physical characteristics of a landform and its vegetation. …
An area or region across which elevation, relief, lithology, geological structure and geological history are similar, and different from those in surrounding regions. …
The natural physical features of the land surface. …
A condition caused by high salt levels in the root zone of a soil, in which water in the soil is attracted to the salt, leaving less available for uptake from the soil by plants. This causes similar symptoms of stress in plants to those caused by normal drought. …
A geographically defined population of a species that is physiologically distinct from other populations. …
The study of functions and processes in living things. …
Relating to the chemistry of plants, plant products, and plant processes. …
The use of medicinal products that are based on plants. …
Microscopic floating aquatic plants, such as algae and diatoms. …
Remediation that uses plants to remove contaminants from soils, sediments, and groundwater. See phytotreatment. …
A substance that causes reduced growth in or kills plants. …
The cultivation of specialized plants that absorb particular contaminants from the soil through their roots or foliage. A form of phytoremediation. …
As a prefix (such as phytoplankton), relating to plants. …
A unit for measuring radioactivity, often expressed as picocuries per litre of air. one picocurie = one million millionth of a curie = 0.037 becquerel. …
Planktonic organisms that range in size from 0.2 to 2.0 micrometres. …
An area of gently rolling hills at the base of a mountain or mountain range. …
A type of glaciation in which large valley glaciers converge and coalesce to form an almost stagnant ice sheet. …
An instrument that is used to measure hydraulic pressure. …
The surface of the static water level in a confined aquifer. …
1 The fuel element in a nuclear reactor. 2 A heap of waste. 3 A column of wood, steel, or concrete that is driven into the ground to support a structure. …
Volcanic lava that has solidified under water and resembles heaps of pillows. …
A small meteorological balloon that is filled with helium and tracked as it rises through the atmosphere, in order to determine how wind speed and direction change with altitude.? …
A small study that is carried out prior to a large‐scale study, in order to test the suitability of a technique or procedure. …
A US politician and conservationist ( 1865 ? 1946 ) who served as the first Chief of the US Forest Service ( 1905 ? 10 ), was Republican Governor of Pennsylvania ( 1923 ? 27 and 1931 ? 35 ), and is remembered for coining the term conservation and advocating scientific approaches to the planned use and renewal of US forest reserves. …
A tall peak on a mountain, or an isolated column of rock. …
A distinctive North American woodland vegetation with scattered trees of medium height, often mixed with sagebrush and other scrub, which is common in the dry arid mountain regions in the west. …
Species of plants, lichens, and micro‐organisms that dominate the vegetation community in the early stages of succession, because they can colonize bare sites. …
A type of insecticide that is used primarily in controlling mites in tree fruit crops. …
The most common ore of uranium, which is mainly composed of the mineral uraninite. See also polonium. …
The extraction of material of value from below the surrounding land surface, by excavation of an open cast mine or a quarry. …
A deposit of a valuable ore (such as mineral‐bearing gravel or sand) that has formed by a concentration of heavy minerals in flowing water, for example by a stream or waves. …
A mass of sand, gravel, or similar alluvial material, that can be extracted through placer mining. …
The extraction of valuable heavy minerals from a placer deposit by washing sand and dirt away with a powerful jet of water, leaving behind the desired mineral (such as gold). Also known as hydraulic mining . …
A form of arrested development where human activities (such as pollution, habitat change, and overgrazing) arrest the natural succession. …
A large body made of rock and metal, or predominantly liquid and gas, which orbits around a star. See also moon. …
The fraction (approximately 30%) of incident solar radiation that is reflected by the Earth?atmosphere system and returned to space, mostly by backscatter from clouds in the atmosphere. See also albedo. …
The lowest level of the atmosphere, where friction is an important force and vertical mixing is common. …
An animal that eats plankton, usually a fish that feeds on zooplankton. …
Aquatic organisms (such as zooplankton and phytoplankton) that are unable to swim because they have no motor power of their own, so they drift around with the tide and ocean currents. contrast nekton. …
Single‐celled protozoanmicro‐organisms that live near the surface of the ocean and have skeletons made of calcium carbonate. See also foraminifera. …
A system of grazing in which two or more grazing units are alternately rested from grazing, in a planned sequence, over a period of years. …
A fire that is started by a deliberate management action. …
The act of drawing up plans and establishing a broad outline for goals, policies, and procedures that will accomplish agreed objectives. See also management. …
The period of time which will be considered in the planning process to which a particular plan relates. …
Any living thing that is not an animal; organisms that belong to the kingdom Plantae. Plants cannot move, lack a nervous system, have cellulose cell walls, and produce food from sunlight and water via photosynthesis. …
In taxonomy, the kingdom of plants. Also known as the plant kingdom. …
An area of forest that has been deliberately sown or planted to produce a cash crop of trees. …
A commercial agricultural system found in tropical countries, in which specialized crops such as bananas, coffee, flowers, and cacao are grown primarily for export to developed countries. …
The deliberate improvement of crops that are grown for food and fibre, based on selecting genes that produce beneficial traits (such as increased production or decreased costs) and transferring them from one plant to another. …
A group of plants (such as broadleavedwoodland) that grows together in a particular area, under given environmental conditions (soil, climate, etc.). …
The taxonomic kingdom (Plantae) that comprises all living or extinct plants. …
The reverse of succession, in which a particular area is successively occupied by less‐developed vegetation. In grassland management, for example, continuous overgrazing of pasture can cause the plant community to change from desirable, highly productive grasses to low quality, unproductive grasses. …
1 A hot, electrically neutral gas of ions and free electrons. 2 The liquid portion of blood, in which cells are suspended. …
An incinerator that operates at extremely high temperatures and destroys highly toxic wastes that do not readily burn. …
A parasiticprotozoan that causes malaria in humans. …
The moisture content at which a soil changes from solid to plastic. …
Durable, flexible, synthetic‐based products that can be shaped by the application of heat or pressure, some of which (such as PVC) are difficult to recycle and pose problems because of their toxic properties. …
The bottom part of the shell of a crustacean, such as a turtle or tortoise. Contrast carapace. …
A zone of seismic and tectonic activity along the edges of crustal plates, which indicate relative motion between plates. …
A widely accepted theory that the Earth's surface is divided into rigid crustal plates, which can move relative to each other (at an average speed of about 70 kilometres per million years; 7 centimetres a year) because of the plastic nature of the underlying upper mantle. Material in the mantle behaves like a plastic, and it is believed that huge slow‐moving convection currents within it can mov…
Soil aggregates that are long and flat, rather than round or spherical. …
A dry, flat‐floored lake bed in a desert, which may flood from time to time, during ephemeral flows after storms. Many playas have a white, crusty layer of salts, formed by salinization. …
The first epoch within the Quaternary period, which began about 1.5 million years ago and lasted until about 10?000 years ago. During the Pleistocene climate switched between glacial and interglacial conditions through a number of cycles. Geological evidence from many locations throughout North America supports a four‐phase model of glacial advances (called the Kansan, Nebraskan, Illinoian, and …
A rudimentary form of social symbiosis, which involves the close proximity of nests of different species of social insects (such as ants). …
The final epoch of the Tertiary period, between about 5.2 and 1.6 million years ago, when climate was relatively warm with little glaciation, and more and larger species of mammal evolved. …
A farm tool with one or more heavy blades that break the soil surface, cut a furrow, and turn the soil over in preparation for sowing and growing crops. Spelled plow in North America. …
1 The process of stopping the flow of water, oil, or gas into or out of a rock formation through a borehole or well. 2 The process of filling and abandoning a well. …
A visible or measurable discharge of a contaminant that is released from a particular source into the air, groundwater, or surface water. …
A heavy, radioactive, metallic element (atomic number 94) that is similar to uranium. It undergoes fission when bombarded with neutrons and is used in the production of nuclear energy and the explosion of nuclear weapons. It occurs in nature in trace amounts, but is also produced as a byproduct of the fission reaction in a uranium‐fuelled nuclear reactor, and can be recovered for future use. See…
A period during which the climate is relatively wet. A pluvial period lasts for decades or longer, between interpluvials. …
Particulate material in the air which is less than 10 micrometres in diameter and includes soot, dust, smoke, fumes, and aerosols. The particles small enough to be inhaled by humans and can damage health. PM10 is a criteria air pollutant that can cause reduced visibility. …
A lung disease that is caused by the long‐term inhalation of fine particulates. …
See present net value, potential natural vegetation. …
A swamp or marsh vegetation underlain by poorly drained, mostly organic soil, which is found on the southeastern coastal plain of the USA, particularly North Carolina. …
A shallow, greyish‐white acidic soil with relatively little organic content and few soil organisms, that develops under coniferous or heath vegetation in temperate to cold moist climates. Podsols are usually infertile and unsuitable for agriculture. …
A soil‐forming process by which the upper horizon of a soil becomes acidic through the leaching of bases which are deposited in the lower horizons (for example, in a pedalfer). It usually occurs under forests in areas with cool, moist climates and quite severe winters, where decomposition of organic matter is inhibited and a peaty mat of acidic organic material builds up on the soil surface. Mix…
A cold‐blooded animal (such as fish and amphibians, but excluding birds and mammals) whose body temperature varies with the temperature of its surrounding environment. Contrast homeotherm. …
A low ridge of sand and gravel that is deposited along the inner bank of a meanderingalluvial stream, where flow velocity is relatively low. …
The point at which an individual or population may come into contact with a chemical of concern that originates from a particular site. …
Pollution that originates from a stationary source or a fixed facility, such as a pipeline or a factory. Contrast non‐point source. …
A chemical that adversely affects health by causing injury, illness, or death. …
At, near, or relating to the North or South Pole, or to the ends (poles) of a magnet. …
A cold air mass that forms in a high‐latitude source region. …
A climate zone that has no warm season, receives limited precipitation, and experiences penetrating cold with temperatures below 10?C throughout the year. …
An air mass that develops over large land masses at high latitude, contains cold, dry, and stable air, and brings cool conditions in summer and cold conditions in winter. …
Easterly winds that develop at high latitudes poleward of the subpolar low. …
A belt of low pressure in the atmosphere at about 60? latitude, where the westerlies meet air that flows from the poles towards the equator. …
A strong, generally westerly jet stream wind that is concentrated in a relatively narrow and shallow current in the upper troposphere above the polar front. …
A major wind belt that circles the Earth, in which the strong, dry winds blow from the northeast in the northern hemisphere, and from the southeast in the southern hemisphere. …
An area of permanent ice at high latitudes, beyond the tundra, where average temperature in each month is below freezing point, and annual precipitation is low (usually less than 250 millimetres a year). Antarctica and the interior of Greenland are the only large land masses in this climate zone. …
An air mass that develops over the oceans in higher latitudes, contains cool, moist air, and brings heavy cloud cover and dull conditions in winter and mild fair weather in summer. …
The area around the poles, in which the climate is permanently cold and inhospitable. …
The natural long‐term cycle of movement of the Earth's magnetic field. Evidence of polar wandering is preserved in the pattern of magnetic changes (palaeomagnetism) in submarine rocks adjacent to mid‐ocean ridges and created by sea‐floor spreading. These show that the Earth's magnetic field has changed as the poles have moved due to continental drift at roughly half‐million‐year interval…
A low‐lying area of land that has been reclaimed from the sea by being artificially drained and protected from flooding by building dykes, and is kept dry by continuous pumping. …
1 A point on the Earth where the axis of rotation intersects the surface or a magnetic pole. See also north pole, south pole. 2 A young tree. See also sapling. …
A written plan of action that is adopted by an individual or group in order to accomplish some particular social or economic goal. …
The process by which problems are identified and acted upon in the public arena, for example by local and national government. …
An umbrella term for a variety of projects that involve politics and the environment, including attempts to study politics using the language and methods of ecology, the study of political struggles for control over natural resources, and research on biodiversity and natural resource exploitation that is intended to inform public policy. …
Social relations that involve authority or power; the science and methods of government. See also environmental politics. …
A traditional form of woodland management in which mature trees are felled at about two metres above ground level in order to promote the regrowth of a crown of poles above the reach of grazing animals. See also coppice. …
Tiny, powdery grains derived from seed plants that contain the male reproductive cells. The pollen of each plant has a distinctive size and shape, which helps in pollen analysis …
A technique that is used to reconstruct past climate. Variations in the frequency of pollen grains at different layers within a soil, sediment, or deposit can be analysed and the results plotted on a pollen diagram. Also known as palynology . …
Part of the back (posterior) legs of the honeybee, in which it stores pollen. …
A graph of the results of a pollen analysis for a particular site, which shows changes in the relative proportions of the pollen of different plants over a period of time, and indicates changes in vegetation and climate. …
The transfer of pollen from the male part of a flower (stamen) to the female part of a flower (the style and stigma), by a pollinator. See also monolectic, oligolectic, polylectic. …
An agent that carries pollen to the female part of a flower, including beetles (cantharophily), flies (myophily), wasps (specophily), ants (myrmecophily), bees (melittophily), butterflies (psychophily), and moths (phalaenophily). …
A substance that pollutes or causes pollution. See also air pollutant, water pollutant. …
The route along which a particular pollutant is distributed, for example within a building or through an environmental system. …
To make impure or dirty with harmful or poisonous substances. …
A person or organization that causes pollution of the environment. …
The principle that the polluter should pay the costs of controlling the pollution they generate, and of cleaning up any environmental damage that is caused by that pollution. …
The process of contaminating or polluting. See also air pollution, noise pollution, water pollution. …
The fee or charge that is levied per unit of pollution, based on the polluter pays principle. …
Any activities that are carried out in order to reduce or eliminate pollution. …
A serious air pollution or water pollution incident in a particular area at a point in time. Also known as an episode . …
Any indicator that is used to show the presence of specific environmental conditions or pollutants. …
An approach to the control of pollution emissions in which polluters can bid for a permit that allows them to create a given amount of pollution. Permits can be resold, and the government can gradually reduce the number of permits that are available so that total pollution emissions can be controlled. …
An approach to the control of pollution in the UK, introduced under the EU Integrated Pollution Prevention and Control Directive (IPPC Directive), that requires any operator of a factory or plant to obtain a permit from the environmental regulator and comply with the conditions in that permit. This replaced integrated pollution control in 2000 . …
An approach to environmental management that is based on preventing pollution (by elimination, reduction, or substitution) rather than dealing with it once it has occurred. …
A system developed by the US Environmental Protection Agency for measuring pollution levels for the major air pollutants that are regulated under the Clean Air Act, based on the health effects of several pollutants. It ranges from 0 (healthy) to 500 (extremely unhealthy). In 1999 the PSI was replaced by the Air Quality Index (AQI). …
A radioactive element that occurs in pitchblende and other ores that contain uranium. …
A synthetic, organic chemical that was once widely used in electrical equipment, specialized hydraulic systems, heat transfer systems, and other industrial products. It is highly toxic and a potent carcinogen, and the management of PCB wastes is tightly regulated. …
Crop cultivation in which a variety of different plants are grown together in the same field. Contrast monoculture. …
A class of organic compounds that contains hydrogen and carbon, and which are found in products such as petroleum and creosote. Some are carcinogens. Also known as polynuclear aromatics (PNAs) or polycyclic aromatics (PCAs). …
A broad class of compounds that are formed primarily from combustion. POM is present in the air in particulate form, and comes from diverse sources including vehicle exhaust, fires, and hazardous waste sites. …
Caused by multiple processes, or created in a number of phases during which different processes were dominant. …
Relating to brackish water which has a salinity between 18 and 30 parts per thousand. …
A pollinator which collects pollen from many species of plant. Contrast monolectic, oligolectic. …
A substance that is made of many repeating chemical units or molecules. Natural polymers include proteins (polymers of amino acids) and synthetic polymers include PVC (a polymer of vinyl chloride). …
A freshwater lake that mixes completely from time to time. …
Something (like a species) that has more than two distinct forms. …
The occurrence of more than one distinct form of individual in a population. …
A small tube‐like marine animal which lives in warm, clear seas and grows with one end attached to the sea‐bed, to rocks, or to other polyps. On the other end is a mouth surrounded by finger‐like, stirging tentacles. Live coral is made of polyps. …
The process by which some stony corals release themselves from their skeleton and drift to a new location, usually induced by stress. …
Feeding on or using many kinds of plant or animal, usually plant species from several families. Contrast monophagous. …
The occurrence of several phenotypes in a population that may be caused by environmental influences but is not due to different genetic types. …
A group of species that do not have one common ancestor species. …
An organism that contains two or more sets of genes or chromosomes. …
A tough polymer plastic that has many everyday uses (including footwear, electrical cable, packaging, and toys), is not biodegradable, and releases hydrochloric acid when burned. …
A pool of still water, often artificially created. A type of freshwater wetland. …
A common sequence of bedforms in alluvial channels, which tend to have narrow, deep sections (the pools) with fine sediment on the bed, alternating with wider, shallower sections with gravel beds (the riffles). This pool and riffle sequence appears to play an important role in the development of meandering. …
1 A group of individuals of the same species who are living in the same area at the same time and share a common gene pool, which makes it possible for them to interbreed. 2 In statistics, the complete set of individuals, alive or not. Contrast sample. …
A subgroup of a population, which is more likely to be exposed to a particular agent, or is more sensitive to that agent, than is the general population. …
An influential book by Paul and Anne Ehrlich ( 1968 ), in which they predicted imminent famine and disaster on a scale unprecedented in world history. …
A campaigning organization in the USA, originally called Zero Population Growth, which was founded by Paul Ehrlich in 1968 and adopted its new name in 2002 . Its main focus is on the relationships between population, environment, and society. …
A sudden sharp reduction in the size of a population that can be caused by disease, environmental stress (such as pollution), or when its numbers exceed the carrying capacity of its habitat. Also known as dieback . Contrast population explosion. See also Malthusian growth. …
The number of individuals of a species that is found in a particular area at a given point in time. …
The total dose of radiation that is received by individuals in a population that is exposed to a particular source or event. …
The study of the factors that affect the growth, stability, and decline of populations, and of the interactions between those factors. …
A sudden rapid rise in the number of individuals in a population in which the birth rate exceeds mortality rate. It generally brings increased environmental damage, through increased resource use, waste production, pollution, and land use change. A population explosion is also widely associated with social impacts such as low living standards, low education standards, unemployment and poverty, mal…
The study of the patterns and causes of variation in genes among a group of individuals within a population. …
The tendency for population growth to continue beyond replacement level, because of a relatively large number of individuals of child‐bearing age. …
A policy or set of policies, usually agreed at national level, designed to manage population growth and improve the quality of life of individuals. See also International Conference on Population and Development. …
A projection of the likely rate and pattern of growth of a population under particular conditions, particularly assumptions about future levels of fertility, mortality, and migration. Every two years the United Nations Population Division produces a set of population projections for every country, based on updated population data and revisions in projection methodology. The 1998 projections, for…
A special type of bar chart that shows the distribution of the population (within a country, region, or the world) by gender and age, usually with the younger ages at the bottom and with males on the left and females on the right. Slowly growing populations (such as the USA) typically have a relatively large elderly population, so they have a population pyramid of reasonably uniform width from bot…
An analysis that estimates the minimum numbers that are required for a population to be viable or self‐sustaining. …
A measure of the amount of pore space within a soil, sediment, or rock, which determines its capacity for holding water, and is expressed as the amount of pore space compared to the total volume of soil or rock, as a percentage. …
igneous rock that contains relatively large crystals set within a finer grained matrix. …
An electrical charge that is created by having fewer electrons than protons. …
Feedback that amplifies the response of the system. Contrast negative feedback. …
A species which is known only from historical evidence, but for which there are hopes that it may be rediscovered. …
A pole or timber stake that is set up to mark something, or to support other structures for fencing. …
1 A basic principle. 2 To make an assumption that is used as the basis for reasoning or hypothesizing. …
The period of time after a waste management or manufacturing facility has been closed, which for monitoring purposes is often taken to be 30 years. …
The reuse of waste materials that have been generated from residential and consumer waste, such as converting wastepaper from offices into corrugated boxes or newsprint. …
Waste materials (such as office paper and aluminium cans) that have been used by consumers and recovered from the waste stream, which are then used as raw materials to make new products. …
After the ice age, or after a glacier has melted from a particular area. …
A modern economy that is dominated by services and information, rather than by industry. …
A philosophy or worldview that emphasizes quality of life over the acquisition of material goods. …
A late 20th‐century view (in art, thought, and society) that what we take to be reality is in effect a human (social) construction rather than a physical entity, which promotes a distrust of objectivity, authority, universality, and moral and ideological absolutes. …
A belief that individuals are constructs of social forces, and that there is no absolute transcendent truth that can be known. …
Water that safe to drink. Also known as drinking water . …
A silver‐white, soft, light, low‐melting metallic element of the alkali metal group that occurs abundantly in nature and accounts for 2.59% of the Earth's crust. It is a macronutrient, one of three main fertilizers (with nitrogen and phosphorus) that are essential for plant growth, and is generally not considered toxic. …
Energy which is possessed by a body because of its position or state, such as water stored behind a dam which can be used to produce hydroelectricity. …
The amount of water that could be evaporated if it was available, which depends on air temperature, insolation, and wind speed. Contrast actual evaporation. …
The amount of water that could be evaporated or transpired if it was available. Contrast actual evapotranspiration. …
An individual or company that is potentially responsible for, or contributing to, contamination at a Superfund site, and therefore potentially liable for cleanup costs. …
The biotic community that would become established on a site if all stages in the succession were completed without interference from humans, under the present environmental conditions. …
The plant community that would develop on a site if all stages in the succession were completed without interference from humans, under the present environmental conditions. …
The maximum possible distribution of a species in the environment. Contrast realized niche. …
Any organism or environmental medium that is in the pathway of a particular contamination from a discharge. …
Any part of the natural or human environment that is currently not thought to have value, but which one day may become valuable as a result of developments in technology and know‐how, and/or changes in market conditions. …
The maximum annual yield of a renewable resource (such as timber from a forest or fish from the sea) that can be obtained on a sustainable basis by using intensive management practices. …
The ability of one chemical to increase the effect of another chemical. …
An imaginary surface that represents the level to which water rises in wells in a confined aquifer: similar to the water table of an unconfined aquifer. …
1 A small, rounded depression in the bedrock of a stream bed, formed by abrasion of small pebbles and cobbles in a strong current. 2 A system of caves and underground rivers formed by water over a prolonged period of time. …