adaptive management (AM) A structured, iterative process for making decisions in the face of uncertainty, with the aim of taking corrective action if monitoring data and models predict a pending problem. Also called adaptive resource management (ARM).

adaptive radiation The evolutionary diversification of a group of organisms into forms that fill different ecological niches in an environment.

adaptive resource management (ARM) See adaptive management.

afforestation The establishment of a forest or stand of trees (forestation) in an area where there was no previous tree cover.

age-based models Population growth models that estimate growth parameters by age classes. Compare with stage-based models.

Agenda 21 One of three non-binding agreements that came out of the 1992 Earth Summit. The agenda outlines a comprehensive set of actions for guiding sustainable development in the twenty-first century, including social, economic, conservation, and political aspects of sustainable development.

agroecological farming Farming practices that integrate farms into a surrounding landscape that conserves and manages biodiversity to enhance ecological processes that support crop production, biological pest control, nutrient cycling, and pollination.

ahimsa Ethical concept of nonviolence and kindness to all living beings, preeminent in the religious traditions of Hinduism, Buddhism, and Jainism.

Aichi Biodiversity Targets Twenty specific goals to slow biodiversity loss and speed international efforts in conservation. Set out in 2010 by the United Nations Convention on Biodiversity’s Strategic Plan for Biodiversity, the goals are built around five themes and specify a target date of 2020 for their achievement.

Aichi Target 11 Sets out the goal of protecting “at least 17 percent of terrestrial and inland water, and 10 percent of coastal and marine areas” in managed and connected areas “integrated into the wider landscapes and seascapes.”

alien species A species, subspecies, or lower taxon occurring outside of its natural range (past or present) and dispersal potential (i.e., outside the range it occupies naturally or could not occupy without direct or indirect introduction or care by humans) [including] any part, gametes or propagule of such species that might survive and subsequently reproduce Also called exotic, foreign, introduced, non-indigenous, and nonnative species. Compare with invasive alien species.

Allee effects A set of phenomena in biology that cause the biological fitness of individuals to be positively correlated with population size (or density). Common examples include mate limitation, cooperative defense, and cooperative feeding.

allele frequency The proportional representation of all of the alleles in a population.

alleles Different forms (i.e., differing DNA sequences) of the same gene—sequences of DNA that are found at the same gene locus (physical, fixed location where a gene sits on a chromosome) but that code for the production of different proteins.

alpha (α) diversity Any measure of biodiversity (e.g., the number of different genes or species) at the scale of a local community or specific location. See also beta diversity, gamma diversity.

animal park See zoo.

Anthropocene Unofficial term for the present geological period in which human beings have come to dominate Earth’s ecosystems and their biophysical processes.

anthropocentrism Worldview that considers human beings to be the primary holders of moral standing and views nature and the environment primarily in terms of their value and benefit to humans. Compare with human exceptionalism, technocentrism.

anthropogenic climate change A general term that refers to a suite of abiotic variables that are changing simultaneously across the planet as a result of human activities that release greenhouse gasses into the atmosphere.

aquarium The aquatic counterpart of a zoo, housing living aquatic animals for public viewing and conservation research.

arboretum A specialized botanical garden dedicated to collections of trees and other woody plants.

artificial incubation Incubation in a device that simulates avian incubation by keeping eggs warm at the correct temperature.

artificial insemination Human assisted introduction of a male’s sperm into a female’s cervix or uterine cavity to try to achieve pregnancy. Often used to increase reproductive output of endangered species.

assisted colonization A conservation strategy that focuses on transplanting threatened species, especially those with poor dispersal abilities, to new sites at higher elevations or closer to the poles in order to help them survive climate change. Also called managed relocation. See introduction.

assurance dilemma A common example from the field of game theory that illustrates why a lack of trust causes two rational individuals to not cooperate with each other even when it is in their best interest to do so. Often presented as a “stag hunt” scenario of two hunters searching for food.

asynchrony See population asynchrony.

autotrophs See primary producers.


beneficiary value See bequest value.

benefit transfer method An economic analysis that estimates the benefit of an ecosystem good or service in a specific situation based on information gathered from a similar place and condition (rather than conducting a unique study of the new situation).

bequest value A subset of existence value. The value that an individual places on ensuring the non-use of certain natural resources so that they will be available for the enjoyment and well-being of future generations. Also known as beneficiary value. Compare with option value.

beta (β) diversity The turnover of biodiversity across local communities in a region, or through time in a local community. See also alpha diversity; gamma diversity.

BIDE parameters Stands for “birth, immigration, death, emigration,” which are key parameters that influence a population’s size and growth through time.

binomial nomenclature The unique two-part Latin name taxonomists bestow on a species, such as Acer rubrum (red maple), Canis lupus (gray wolf) or Homo sapiens (human). The first name is that of the genus, the second name identifies the species (Canis lupus, gray wolf; Canis simensis, Ethiopian wolf).

biocentrism Worldview that extends inherent value and consideration to all living beings, and holds that humans hold no particular moral superiority over other organisms. Compare with anthropocentrism; ecocentrism.

biodiversity hotspot A defined geographic area that has particularly high levels of biodiversity and which is also highly threatened by human activities.

biodiversity The variety of life on Earth, including all of its genes, populations, species, communities, and biomes. Also known as biological diversity.

biological asynchrony See population asynchrony.

biological community A collection of species that occupy and interact in a particular location.

biological diversity See biodiversity.

biological species concept The concept that defines a species as a group of individuals that can potentially breed among themselves in the wild and that do not breed with individuals of other groups. Compare with evolutionary species concept, morphological species concept.

biomagnification Process whereby toxins become more concentrated in the tissues of organisms at higher levels in the food chain.

biophilia The innate tendency by humans to seek connections with nature and other nonhuman forms of life.

biotic homogenization The process by which invasive alien species replace native flora and fauna, in turn causing ecosystems to lose their biological uniqueness.

botanical garden An ex situ facility that is dedicated to the collection, cultivation, and preservation of plants. Compare with arboretum.

Brundtland Commission Common name (from its chairman, Gro Harlem Brundtland) for the UN’s World Commission on Environment and Development (WCED). The Commission’s 1987 report, Our Common Future, launched a global focus on sustainable development.

bushmeat Wildmeat, or game meat obtained from non-domesticated mammals, reptiles, amphibians and birds that are hunted for food.

bycatch Animals, including marine mammals, sea turtles, and fish that are not the target of commercial fishing, but which are caught and killed unintentionally during large-scale fishing operations.


Canada Nature Fund A Canadian government fund (enhanced with support from nongovernmental sources) formed in 2018 to spearhead the establishment and integration of protected areas into a nationwide protected network.

capture-mark-recapture (CMR) An approach to estimating a species’ abundance that involves capturing individuals and marking them in one timeframe, then capturing individuals and recording the number of previously marked animals in a later timeframe. Abundance is estimated based on the ratio of recaptured animals to total animals captured in the second timeframe.

carrying capacity (K) The maximum number of individuals (or biomass) of a species that an area can support given the limiting resources available.

census A count of the number of individuals in a population; for example, the Audubon Society’s Christmas Bird Count.

charismatic megafauna Large animals like whales, pandas, or elephants that elicit strong emotional responses in people, who may then express a willingness to pay for their preservation despite receiving no direct benefit from their existence.

choice experiments A method of estimating the value of ecosystem goods and services that asks respondents to choose between scenarios with two groups of items, each of which has a different cost. Choice experiments focus on trade-offs among varying characteristics and impacts in the different scenarios.

choice modeling method A method of estimating the value of ecosystem goods and services in terms of trade-offs among hypothetical choices that have multiple possible outcomes.

class Unit of taxonomic classification into which related orders of species are grouped.

climatic envelope models (CEMs) A specialized form of species distribution model in which the main predictors of a species’ distribution are climate-related variables. CEMs describe relationships between a species’ current distribution and climatic variables like temperature and precipitation to describe the species’ climatic niche, which can be compared to that for future climate conditions predicted from a general circulation model.

climatic niche The set of climatic conditions to which a species is adapted.

cloning The process of creating a new multicellular organism through asexual reproduction of cells.

closed population A population in which no individuals are entering or leaving the population through birth, immigration, death, or emigration (the BIDE parameters). Compare with open populations.

co-design The process of including all relevant stakeholders in the discussion and development of coordinated management plans for sustainable use of natural resources. Also called participatory design.

cold-edge expansion Expansion of a species’ range into regions that were once beyond its “cold” limits, but which are now accessible as a result of climate warming. Also called leading-edge expansion.

common-pool resources Natural resources that are owned by national, regional, or local governments as public goods, or by communal groups as common property.

community and ecosystem diversity The different biological communities and their associated ecosystems that make up whole landscapes.

community structure The organization of a community, including (though not limited to) its trophic structure, species composition, and food web complexity.

community-based natural resource management programs (CBNRMs) Programs where governments grant local landowners and communal groups the authority to manage wildlife in their landscapes in ways that help build sustainable economies and improve people’s livelihoods. CBNRMs are particularly common in Africa.

competitive exclusion principle The principle that no two species can coexist when using the same resource, at the same time, in the same location, because one of the competing species will exclude the other.

Conference on Biological Diversity See Earth Summit.

connectance A measure of network complexity that quantifies the proportion of all possible interactions between species in an interaction matrix that are actually realized. Connectance (C) is equal to L/S2, where L is the total number of links in the matrix and S is the total number of species. See also linkage density.

conservation easements A voluntary legal agreement that a landholder enters into with another party, such as a government agency or land trust, that places some restrictions on how the property will be used in the future in order to ensure some value for conservation, but which maintains certain options or activities for the original owner. Easements are typically made in perpetuity, and may have legal and/or tax benefits for the original owner.

conservation refugees A term applied to people who are displaced from their lands and homes by the establishment of protected areas. A continuing and serious problem, since as much as 20 percent of the world’s population live in hotspots of biodiversity that some conservationists argue need urgent protection.

consumer surplus The difference between the total amount that consumers are willing to pay for a product or service (indicated by the demand curve) and the total amount they actually do pay (the market price). Compare with economic surplus.

consumptive use value Direct use value assigned to goods that are collected and consumed locally. Compare with productive use value.

contingent valuation A method of estimating the value of ecosystem goods and services that asks respondents to state their willingness to pay for (or to accept compensation for doing without) an ecosystem service, based on a hypothetical scenario and description of the service.

continuous-time model Mathematical model for population growth where reproduction occurs continuously, without regard to seasons or other discrete time periods. Compare with discrete-time model.

Convention on Biological Diversity (CBD) A legally binding, multilateral treaty that came into force at the end of 1993 and has 196 Parties (countries) that are obligated to implement its provisions. The CBD has three main goals: (1) conservation of biodiversity, (2) sustainable use of biodiversity, and (3) fair and equitable sharing of the benefits arising from the use of genetic resources. See also Aichi Biodiversity Targets; Earth Summit.

conventional farming High-production farming based on monoculture crops (often genetically modified crops, GMOs) that are managed with heavy machinery and external inputs like synthetic fertilizers and pesticides.

cooperative defense When aggregations of animals defend each other against shared predators.

cooperative feeding Foraging or hunting in which groups of animals work together and share the food they acquire.

coral bleaching Effect when warming water causes corals to expel the symbiotic algae living in their tissues, so that the corals turn white and lose their biological functioning.

core habitat See interior habitat.

cost-based techniques A set of economic valuation methods that are based on estimating the cost of avoiding damages due to lost services (damage cost avoided), the cost of replacing environmental assets after they are lost (replacement cost), or the cost of providing substitute services (substitute cost).

covenants Similar to conservation easements, but usually are not permanent and are void if a protected property changes ownership.

crisis discipline Refers to a field like conservation biology (or cancer research or foreign policy) in which urgent issues require practitioners to take action even in the absence of complete information.

cryosphere The frozen-water portion of Earth’s ecosystems.

cryptic biodiversity The existence of undescribed but genetically distinct species that look similar to, and consequently have been wrongly classified as, a described species.

cultural services Nonmaterial benefits people obtain from ecosystems.


de-extinction The process of using cloning to create an organism that is a member of, or resembles, an extinct species. Also called resurrection biology or species revivalism.

debt-for-nature swap Agreement in which a developing country agrees to fund conservation activities in exchange for the cancellation of some of its debt owed to a developed nation.

decomposers Organisms that obtain their nutrients and energy from the waste products (detritus) and dead tissues of other organisms. Also called detritivores.

deep ecology An environmental movement based on the premise that the living world as a whole should be regarded as having the inalienable right to live and flourish, independent of its instrumental values for human use. The movement’s philosophy emphasizes biodiversity protection, personal lifestyle changes, and working toward political change.

demographic stochastisity Random fluctuations in population size that occur because the birth and death of each individual in a population is a discrete and probabilistic event. Small populations are particularly susceptible to declines in population size caused by stochasticity. Also called demographic variation. Compare with environmental stochasticity.

demographic transition The historical shift in demographics from a population characterized by high birth rates and high infant death rates in societies with minimal technology, education (especially of women), and economic development, to population demographics characterized by low birth rates and low death rates in societies with advanced technology, higher education, and economic development.

density-dependent growth A pattern of population growth in which the growth rate at any given time is dependent on the current size of the population.

desertification The process by which once fertile land becomes a desert, usually due to drought, deforestation, or poor land management practices (e.g., intensive agriculture) that alter the water budget.

deterministic model A population model in which parameters such as birth and death rates are fixed, leading to only one possible outcome for population size. Compare with stochastic model.

detritivores See decomposers.

dilution effect A biological mechanism that reduces the risk of infection by zoonotic pathogens (pathogens transmitted from animals to human) by reducing the prevalence of the pathogen among the animal hosts that transmit the disease.

direct use value The economic or social value of ecosystem goods or services that are used directly by individuals. These include consumptive uses (e.g., harvesting goods) and non-consumptive uses (e.g., recreation).

discounting An economic tool used to estimate the present value of costs or benefits that might be incurred in the future. It determines the discounted value, or present value.

discrete-time model Population growth model that treats time in discrete packets, whether years, seasons, or some other time unit, with population growth (reproduction) occurring only once in each period. Compare with continuous-time model.

dispersal limitation Limits to the dispersal ability of an organism, which constrains a species population growth and geographic distribution.

diversified farming Farming practices that integrate several crops and/or animals in the production system to promote agrobiodiversity, ecosystem services, and reduced need for external inputs.

double clutching The technique of removing the first clutch of eggs from a rare female bird so that she will lay and raise an additional clutch while her first clutch is raised by another bird of a related species. Two clutches of the rare species’ eggs are therefore produced each season.

dynamic vegetation models (DVMs) Models that use time series of climate data (e.g., temperature, precipitation, number of days with sunshine) to explain the current distribution of plant functional types, and those relationships are subsequently used to project shifts in entire vegetation zones and biomes at a regional or global scale.


Earth Summit Formally called the United Nations Conference on Environment and Development, or UNCED. Held in Rio de Janeiro in 1992, the Earth Summit brought together representatives from over 170 countries, including heads of state, leaders of the UN, and individuals from major conservation organizations, specialized agencies and intergovernmental organizations, and from groups representing religions and indigenous peoples to discuss combining increased protection of the environment with sustainable economic development.

ecocentrism Wholistic worldview that considers the Earth as a biophysical system that includes humans, nonhuman life, and the sum of all the physical and biological processes that are required to sustain life. Compare with anthropocentrism; biocentrism.

ecological economics A subdiscipline of the field of economics, which quantifies the instrumental value of nature and its biodiversity.

ecological efficiency The percentage of energy captured at one trophic level that is transferred to the next highest trophic level in a food web. As a “rule of thumb,” about 10% of the energy produced by a lower trophic level tends to become available in the next trophic level; efficiency varies, however, among ecosystems and organism types.

ecological niche models See species distribution models.

ecological traps Areas of low-quality habitat that reduce survival and reproduction.

ecologically (functionally) extinct Refers to a species that has been so reduced in numbers that it no longer has a significant ecological impact on the biological community or ecosystem in which it resides.

economic surplus The net economic benefit of a good or service—that is, the sum of consumer surplus and producer surplus.

ecosystem disservice An ecological process (e.g., supporting service of ecosystems) that has a negative impact on something that humans value (e.g., primary productivity by algae that overgrows and kills a coral reef).

ecosystem engineers Species that create new physical habitat or that extensively modify existing environments through their biological activities.

ecosystem management See ecosystem-based management.

ecosystem services Nature’s contributions to people; the plethora of benefits that humans receive from both natural and managed ecosystems, including things like the production of consumable goods (e.g., production of fish from oceans, or wood from forests), nonconsumable services (e.g., protection from natural disasters like floods, or biological control of pests and disease), and cultural services (e.g., recreation, or ecotourism).

ecosystem-based management An environmental management approach, usually applied to management of natural resources at the scale of whole landscapes or ecoregions, that recognizes the full array of interactions within an ecosystem, including humans, rather than considering single issues, species, or ecosystem services in isolation.

ecosystem A biological community together with its associated physical and chemical environment.

ecotones See edge habitats.

ecotourism A type of recreational tourism that involves people visiting places and spending money wholly or in part to experience and enjoy natural ecosystems and their biodiversity (such as rain forests, African savannas, coral reefs, deserts, the Galápagos Islands, and the Everglades), or to view particular “flagship” species (such as elephants, on safari trips).

edge effects A suite of physical and biological changes that tend to occur at patch edges. Many of these changes, such as altered microclimates and increased prevalence of parasitism or disease, can be detrimental to biodiversity.

edge habitats Areas of transition between different habitat types. Also known as ecotones, edge regions are often disturbed habitat whose area increases with habitat fragmentation. See also ecotones.

effective population size (Ne) The number of breeding individuals in a population (or the number of individuals that contribute genes to the next generation).

empty niche hypothesis Proposes that the primary way alien species become established in a new community is by exploiting a vacant niche—either by using biological resources in a new way, or by performing a completely new role that was previously unfilled by a native species.

endemic Organisms that are native to and occur only in a given location.

enemies release hypothesis Proposes that while populations of alien species tend to be controlled by natural enemies, such as pathogens, predators, and parasitoids, in their native ranges, when a small number of individuals of an alien species are introduced to a new location, their natural enemies may not be transported with them.

environmental ethics A branch of philosophy that studies the foundation of environmental values as well as societal attitudes, actions, and policies to protect and sustain biodiversity and ecological systems.

environmental justice The fair treatment of all people regardless of race, color, national origin, or income in respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. The environmental justice social movement seeks to empower poor and politically marginalized people, who are often members of minority groups, to protect their own environments and well-being.

environmental stochastisity Unpredictable spatial or temporal fluctuation in a population’s demographic rates (birth and death) that are caused by varying environmental conditions. Compare with demographic stochasticity.

eutrophication When a body of water becomes overly enriched with nutrients like nitrogen and phosphorus, frequently due to runoff from the land, and subsequently causes a dense growth of plant life and death of animal life from lack of oxygen.

evapotranspiration Sum total transfer of liquid water to atmospheric water vapor via (1) evaporation of water from terrestrial and aquatic surfaces and (2) plant transpiration. In plant transpiration, the water plants take up from the soil travels through the plant and is released into the atmosphere as vapor through stomata in the leaves.

evolutionary species concept The concept that defines a species as a group of individuals that share similarities of their DNA (e.g., 95% overlap in nucleotide sequence), and hence their evolutionary past. This is the most recent of several approaches to recognizing and classifying species. Compare with biological species concept, morphological species concept.

evolutionary-ecological land ethic One of three environmental philosophies that shaped conservation policies in the United States and elsewhere. This conservation ethic, promulgated by Aldo Leopold, is based on the belief that the most important goal of conservation is to maintain the health of natural ecosystems and the ecological processes they perform. Espouses a middle ground between exploitation and total human control over nature on the one hand, and complete preservation of wilderness with no human presence or activity on the other. See also preservationist ethic, and resource conservation ethic.

ex situ conservation Off-site conservation. Preservation of living individuals in artificial, human-built environments like zoos, aquariums, and botanical gardens. Also applies to captive-breeding programs and to the collection and preservation of genetic materials (see frozen zoos; seed banks).

existence value the benefit people receive from knowing that a particular environmental resource, endangered species, or any other organism or thing exists (e.g., a species, wilderness area, or ecosystem such as tropical rainforest). Quantified by the amount people are willing to pay to protect or preserve species, habitats, and other natural resources from being irreparably harmed or completely lost. Compare with intrinsic value.

exotic species See alien species.

exponential growth model A continuous-time mathematical model for population growth based on the instantaneous rate of increase (r). Compare with geometric growth model; logistic growth model.

externalities Side effects or consequences of an industrial or commercial activity that affect other parties without those effects being reflected in the cost of the goods or services involved. Externalities lead to market failures where the profits of a transaction benefit the business, but certain costs of the transaction are paid by individuals or groups of individuals that were not involved in the transaction.

extinct in the wild Occurs when a species is no longer found in the wild, although individuals may remain alive in ex situ facilities like zoos, botanical gardens, or other artificial environments.

extinction The loss of a species that occurs with the death of the last individual of the species, resulting in the loss of that species’ genetic diversity and ending its evolutionary history. See also ecologically extinct; extinct in the wild; extirpated; globally extinct.

extinction cascade A series of linked extinctions whereby the extinction of a key species triggers the extinction of other species.

extinction debt The future extinction of species due to events that have occurred in the past. The extinction debt occurs because of time delays between impacts on a species, such as destruction of habitat, and the species’ ultimate disappearance.

extinction thresholds Thresholds of habitat size that are required for species to persist and complete their life cycles.

extinction vortex The tendency of small populations to spiral toward extinction at an ever-increasing rate as it becomes more and more vulnerable to the effects of demographic and environmental variation and reduced heterozygosity.

extirpation The local extinction of a species population from a biological community, even as populations of the species still exist elsewhere in other local communities.


family Unit of taxonomic classification into which related genera are grouped.

fences-and-fines An approach to conservation that involves delimited separation of protected areas from people (“fences”) and the implementation and enforcement of protective regulations (“fines”).

finite rate of increase (λ) The geometric rate of increase + 1; (= R + 1).

fixed effort (proportional harvest) model A mathematical model for determining maximum sustainable yield when the number of individuals harvested from a population is directly proportional to the size of the population.

fixed quota (constant harvest) model A mathematical model for determining maximum sustainable yield when the number of individuals harvested from a population is a constant—both independent of the population size and independent of the amount of effort put into harvesting.

flagship species A species used to attract the attention and concern of the public, often invoked to raise awareness of the plight of a given ecosystem or region. Flagship species are usually appealing and charismatic to humans (e.g., elephants, jaguars, giant pandas).

food web A network of feeding relationships among species interacting as a community.

founder effect A specific type of genetic bottleneck that occurs when a small number of individuals breaks away and becomes isolated from a larger population, thus founding a colony that has less genetic diversity than the original population. This can occur when a population becomes fragmented by human activities.

frozen zoos Gene banks that collect and store tissues, cells, gametes (sperm and egg cells), and DNA of endangered animals in cryogenic freezers.

functionally extinct See ecologically extinct.


game theory The study of mathematical models of strategic interaction in between rational decision-makers. See assurance dilemma; prisoner’s dilemma.

gamma (γ) diversity Any measure of biodiversity (e.g., the number of different genes or species) at the scale of a whole geographical region (landscape). See also alpha diversity; beta diversity.

gap analysis An assessment of how close an existing network of protected areas comes to meeting a set of defined conservation and social goals, followed by a process of identifying “gaps” and prioritizing additional protected areas that are required to achieve those goals.

gene A sequence of nucleotides (DNA sequence) that are located at a specific point on a chromosome (the locus), and which code for a specific protein. The gene is the unit of heredity that is transferred from a parent to offspring, and which determines some characteristic of the offspring.

gene pool The total array of genes and alleles present in a population or subpopulation.

general circulation models (GCMs) Models that forecast the mean, range, and variation for future climatic variables like temperature and precipitation based on predictions of variables like radiative forcing and greenhouse gas levels. Also called global climate models.

Genesys An online data portal that contains records of germplasm accessions from institutions around the world to facilitate the access to, and use of, accessions in ex situ gene banks.

genetic bottleneck An extreme reduction in a population’s genetic diversity that occurs when a population’s size is extremely reduced, for example following a natural disaster or outbreak of disease. Compare with founder effect.

genetic diversity The genetic variation found within species, both among individuals within single populations and among geographically distinct populations. See also heterozygosity and polymorphism.

genetic drift The change in allele frequencies from one generation to the next, resulting from random chance rather than being driven by natural selection or other evolutionary constraints. Can have significant effects on small populations, in which an allele that occurs at a low frequency has a significant probability of being lost in each generation.

genetic variability See heterozygosity.

genotype The particular combination of alleles that an individual possesses.

genus (plural, genera) Unit of taxonomic classification that includes one or more species. In binomial nomenclature, the first term identifies the genus.

Geodatabase A GIS file format recommended by the Environmental Systems Research Institute (ESRI) for use in its popular GIS software ArcGIS.

geoengineering The deliberate large-scale manipulation of Earth’s land, atmosphere, and oceans in an attempt to counteract climate change and maintain a habitable climate for humans (e.g., cloud seeding, orbiting “sunshades,” enhanced carbon sequestration).

geometric growth model A discrete time mathematical model for population growth based on the geometric rate of increase (R). Compare with exponential growth model; logistic growth model.

geometric rate of increase (R) Population growth rate measured as (b – d), or the rate of birth (per individual) minus the rate of death (per individual) during a given timeframe (often 1 year). Compare with instantaneous rate of increase (r).

global climate models (GCMs) See general circulation models.

Global Environment Facility (GEF) Created at the 1992 Earth Summit, the GEF is an international partnership of 183 countries, international institutions, civil society organizations, and private sector enterprises, and provides funding for environmental projects, many of which link to the United Nations Sustainable Development Goals.

globally extinct When, after a thorough search and investigation, it is determined that no individuals of a species are alive anywhere in the world.

green infrastructure See natural infrastructure.

gross primary production (GPP) Total biomass production by autotrophs. It is controlled by the rate of photosynthesis, which dictates the mass of inorganic CO2 that is captured from the air and water and converted into organic carbon in tissues of the primary producers. Compare with net primary production.


habitat conversion See habitat loss.

habitat corridor A continuous strip of protected habitat that runs between and connects two protected areas to facilitate dispersal. Compare with stepping stones.

habitat degradation Refers to a suite of human activities that make the habitats in a landscape less conducive to life, in turn eroding biodiversity. These activities include many forms of pollution (pesticides, heavy metals, nutrients, plastics, personal care products), as well as activities that lead to desertification, erosion, and sedimentation, all of which make habitats less hospitable.

habitat destruction See habitat degradation.

habitat fragmentation The process by which a larger expanse of habitat is subdivided into smaller pieces, or patches, within a landscape. Fragmentation leads to an overall reduction of habitat area as well as changes in patch shape, size, interior-to-edge ratios, connectivity, microclimates, and other factors that can alter biodiversity in a myriad of ways.

habitat loss Complete elimination of habitats, along with their biological communities and ecological functions, due to the conversion of natural or semi-natural habitat (e.g., a managed forest) into human-dominated habitat (e.g., a village or parking lot).

Half-Earth Project An ambitious initiative to protect one-half of Earth’s lands and seas in order to manage sufficient habitat to reverse the rate of species extinctions and ensure the long-term health of the planet.

hedonic pricing method An economic analysis that uses variation in the pricing of homes or other real estate to determine how people value certain attributes of the property and its surrounding characteristics. For example, variation in housing or other real estate prices can be used to estimate the value of local environmental attributes that surround the properties.

herbivores Organisms that eat plants or other photosynthetic organisms. Also called primary consumers.

heterozygosity The presence of more than one allele of the same gene in an individual or population. Heterozygosity is quantifiable as the proportion H of gene loci at which the average individual in the population has two or more alleles. Also called genetic variability.

heterozygous Condition of an individual having two different forms (i.e., two alleles) of a gene on homologous chromosomes.

higher consumers (2°, 3°) Predators that kill and eat other animals. Secondary consumers (carnivores) feed on herbivores, and tertiary consumers feed on other carnivores. See also omnivores.

homozygous Condition of an individual having two identical alleles of the same gene on homologous chromosomes.

horizon scanning A procedure for gathering information to identify potential threats from invasive species before they are introduced to a novel ecosystem. Usually the first step in forming a management plan for invasive species.

human exceptionalism An extreme form of anthropocentrism, especially as promulgated by certain Christian groups who assert the complete moral and biological superiority and rights of humans (whom they believe to be made in God’s image) over all other life forms. Compare with biocentrism; ecocentrism; technocentrism. Also called human supremacism.

human supremacism See human exceptionalism.

hybrid Intermediate offspring resulting from mating between individuals of two different species.


immobilization The process within nutrient cycles by which biologically essential elements (e.g., nitrogen, phosphorus, and potassium) in their soluble inorganic forms are taken up and reused by plants and microbes for new growth. Compare with mineralization.

in situ conservation On-site conservation. Preservation of natural communities, ecosystems, landscapes, and populations of endangered species in their natural habitats, such as with management of protected areas.

in vitro fertilization Fertilization of an egg by sperm outside the body, followed by implantation of the embryo into the uterus of an animal.

inbreeding Nonrandom mating between relatives (i.e., two individuals that are more similar in their genotypes than a random mating pair would be). Results in a loss of heterozygosity.

inbreeding depression The loss of heterozygosity from inbreeding. Often results in reduced biological fitness, characterized by higher mortality of offspring, fewer offspring, or offspring that are weak or sterile.

Indigenous Protected and Conserved Areas (IPCAs) Lands where Indigenous peoples and their legally recognized governments play the primary role in managing, protecting and conserving their ecosystems while building sustainable local economies. IPCAs aim to safeguard Indigenous peoples’ rights and secure a space where communities can practice their traditional ways of life, while also maintaining biodiversity.

indirect use value The economic or social value of ecosystem goods or services that people derive from nature without the need to harvest, consume, or destroy the resource (e.g., flood control).

Industrial Revolution The period in the eighteenth and nineteenth centuries during which technology proliferated and predominantly agrarian, rural societies in Europe and America shifted and became industrial and urban.

instantaneous (intrinsic) rate of increase (r) Population growth rate measured as (b – d), or the rate of birth (per individual) minus the rate of death (per individual), but calculated for growth that is constant and continuous through time rather than for growth in discrete time units. Compare with geometric rate of increase (R).

instrumental value The value that a thing has in helping us get something else we want. Something has instrumental value if it serves as a means to an end (e.g., currency has intrinsic value because it allows us to purchase things we want). Nature and its biodiversity have instrumental value in the form of the goods and services they provide to humanity. Also called utilitarian value. Compare with instrinsic value.

insurance value See option value.

integrated conservation and development projects (ICDPs) A conservation strategy that seeks to meet the goals of biodiversity conservation while dealing with the social and economic needs of communities who might otherwise threaten biodiversity.

intergenerational sustainability A Chinese philosophy, dating to around the eleventh century ce, of maintaining sacred landscapes and natural systems so that they are preserved for future generations. See also seventh generation principle.

interior habitat The habitat of a patch minus its edge habitat. The proportion of interior habitat decreases as patch size declines. Also called core habitat.

intraspecific competition Competition among individuals of the same species.

intrinsic value The inherent value that a thing (e.g., a species or ecosystem) possesses simply because of its existence, and which is independent of its instrumental value to human society. See also instrumental value, relational value.

introduction A program that moves individuals into an area outside their historical range because their original range is no longer suitable. Also called assisted colonization or translocation. Compare with reinforcement; reintroduction.

invasive alien species (IAS) An alien species which becomes established in natural or seminatural ecosystems or habitat, is an agent of change, and threatens native biological diversity Also called alien invasive species.

IUCN Red List A comprehensive and standardized listing of the global conservation status of more than 90,000 threatened and endangered species. Compiled by the International Union for the Conservation of Nature (IUCN).


keystone species A species that has a disproportionate impact (relative to its numbers or biomass) on the organization of a biological community. Loss of a keystone species can lead to a broader loss of biodiversity.

kingdom Large unit of taxonomic classification; for example, the kingdom Animalia includes all animals, while Plantae contains all green plants.

KML A GIS file format that uses Keyhole Markup Language to view spatial information in Google Earth.


land conservancy See land trust.

land trust A private, nonprofit conservation organization that, as part of its mission, assists in land acquisitions through conservation easements and covenants, and then stewards those lands as part of their own portfolio of protected areas.

land-use change The conversion of one habitat type to another, usually human-engendered such as when a natural forest is converted to a suburban housing development, or a natural grassland is converted to agricultural production. The single greatest cause of habitat loss.

landrace A variety of food crop that has unique genetic characteristics and is cultivated in a very small area of the world. Usually refers to a variety (or its wild relative) that gave rise to the hybrids that dominate modern monocultures. Landrace genomes harbor variability that is crucial to maintaining the high productivity of today’s agriculture in the face of climate change and the evolution of new and/or resistant strains of pests and diseases.

landscape A large geographic region that spans multiple biological communities and ecosystems and includes different habitat types.

landscape mosaics Heterogeneous landscapes that are patchy and subdivided, where some habitats have been lost and converted to human uses, others have been heavily degraded, and those that remain intact are small, fragmented, and disconnected from one another. Also called patch mosaics.

law of demand A rule that states that if all other factors remain equal, people’s demand for a good or service will decrease as the price of the good or service increases.

leading-edge expansion See cold-edge expansion.

Leslie matrix A discrete-time, age-based matrix model for estimating the growth of populations with age or stage classes.

linkage density A measure of network complexity that quantifies the number of interactions each species has in a food web. Linkage density (D) represents the average number of interactions between species as D = L/S, where S is the total number of species in an interaction matrix, and L is the total number of links in the matrix. See also connectance.

Living Planet Index (LPI) An indicator of the state of global biodiversity, based on trends in 16,700 vertebrate populations of species from around the world. These population trends are maintained in the Living Planet Database and published in the Living Planet Report by the Zoological Society of London.

Living Planet Report A comprehensive report on global biodiversity, including the Living Planet Index, published every two years by the World Wildlife Federation (WWF).

locally extinct See extirpated.

locus Plural, loci. See gene.

logistic growth model Mathematical model for density-dependent population growth that builds on the geometric growth model and exponential growth model by adding a term that accounts for the constraint of carrying capacity.

love it to death syndrome A danger of ecotourism whereby overly abundant and assertive tourists themselves become the source of environmental destruction to the site they are visiting.


mainland–island model A modification of the classic metapopulation model in which a large mainland population with a low probability of extinction serves as a source population, providing immigrants to nearby small populations. Also called the propagule rain model.

managed relocation See assisted colonization.

manifest destiny In the U.S. in the nineteenth century, the widely held belief that it was destined and inevitable for Americans to move west and occupy North America from coast to coast, and to become prosperous as they did so.

market failure A situation where the profits of a business transaction benefit the business, but certain costs of the transaction are paid by individuals or groups of individuals that were not involved in the transaction. Most commonly occur when externalities cause resources to be misallocated, allowing a few individuals or businesses to benefit at the expense of the larger society.

market pricing method An economic analysis that gives the value of either the quantity or quality of an ecosystem good or service that is bought and sold in a commercial market. Determined by the laws of supply and demand.

Marxan A widely used software program for designing protected area networks.

mass mortality event (MME) A rapid, catastrophic die-off of organisms that kills more than 90% of a population in a short time.

mate limitation When sexual reproduction becomes limited because population density gets sufficiently low to reduce the chance of finding a mate.

matrix model An array of numerical data arranged in columns and rows.

maximum sustainable yield (MSY) The maximum level at which a natural resource can be routinely harvested or exploited without long-term depletion. MSY calculations are widely used in managing fisheries, timber forests, and game species.

meta-analysis Synthesis of information from a large number of studies whose data and results are collated and subjected to collective statistical analysis.

metapopulation A collection of local populations that are spatially separated from each other in the individual patches of a landscape, but are connected to each other by the dispersal and exchange of individuals.

Millennium Development Goals (MDGs) A set of 8 goals for sustainable development that arose out of the United Nation’s Millennium Summit of 2000. Has been superseded by the 2030 Agenda for Sustainable Development and its Sustainable Development Goals.

mineralization The process within nutrient cycles by which biologically essential elements (e.g., nitrogen, phosphorus, and potassium) from organic tissue are returned to their soluble inorganic forms, which can subsequently be used by plants and microbes. Compare with immobilization.

minimum dynamic area (MDA) The area of habitat required to maintain a minimum viable population of a species.

minimum viable population (MVP) The smallest population size predicted to have a very high chance (e.g., 95%) of persisting for the foreseeable future (e.g., 100 years).

morphological species concept The concept that a group of individuals is recognized as a species because they are morphologically, physiologically, or biochemically distinct from other groups. Compare with biological species concept, evolutionary species concept.

morphospecies A group of individuals that, based on the level of similarity of their morphological characteristics, are probably a distinct species.

mutational meltdown The accumulation of harmful mutations in a small population, which leads to loss of fitness and decline of the population size, which then leads to further accumulation of deleterious mutations.


Nagoya Protocol A supplementary agreement to the 1992 UN Convention on Biological Diversity (CBD) that sought to establish an international protocol for the fair and equitable sharing of benefits that arise from the access and use of genetic resources.

national biodiversity strategy and action plans (NBSAPs) Plans that describe how each of the 196 nations that are parties to the United Nations Convention on Biodiversity (CBD) will accomplish goals in the CBD’s Strategic Plan for Biodiversity 2011–2020, which includes the 20 Aichi Biodiversity targets.

National Environmental Funds (NEFs) Conservation trust funds or foundations in which a board of trustees—composed of representatives of the host government, conservation organizations, and donor agencies—allocates the annual income from an endowment to support inadequately funded government departments and nongovernment conservation organizations and activities.

native species A species, subspecies, or lower taxon occurring within its natural range (past or present) and dispersal potential (i.e., within the range it occupies naturally or could occupy without direct or indirect introduction or care by humans). Also called indigenous species.

natural infrastructure The collection of genes, species, and biological communities that comprise the natural and managed ecosystems on which people depend, and which provide goods and services to society. Also called green infrastructure.

Nature Needs Half Project An international coalition of scientists, conservationists, nonprofits, and public officials working together to protect at least half of all nature on Earth—land and water—by 2030 in order to support the existence of nature and the services it provides.

neoendemic A species that occupies a small area because it has only recently evolved from a closely related species.

net primary production (NPP) The difference between gross primary production (GPP) and the organic carbon lost as heat during respiration (R) by autotrophs; NPP = GPP – R.

niche differentiation Different species either use different resources or use the same resource differently in space or time, thus reducing competition for resources among different species. Also called niche partitioning, or niche complementarity.

niche partitioning See niche differentiation.

noble savages The romanticized ideal of prehistoric and/or primitive cultures living in harmony with nature, managing their natural resources sustainably, and being free from the corrupting influence of modern civilization and technology.

non-use value The value that people and governments assign to ecosystem goods and services even if they never have and never will use them. See bequest value; existence value.

nonconsumptive use value Value assigned to an ecosystem service that is not extracted but still used and valued, such as scenic beauty or the use of a river for transportation.

nongovernment organizations (NGOs) A nonprofit organization that operates independently of any government, whose purpose is to address a social or political issue. Among the major NGOs involved in conservation and sustainable development activities are the World Wildlife Fund, the Nature Conservancy, and Conservation International..

novel environments hypothesis Proposes that successful invasive species are particularly well adapted for, and successful in, habitats that have been directly modified or disturbed by human activities.

novel weapons hypothesis Proposes that alien plant species gain advantage over native plants by expressing allelopathic chemicals that can kill the native vegetation.


omnivores Animals that eat food from more than one trophic level, for example, eating both plants and other animals.

ontogenetic niche shifts Changes in species’ habitat requirements as they complete the different parts of their life cycles (e.g., a tadpole’s need for an aquatic environment while the adult frog can live on land).

open populations A population whose size potentially changes through time as individuals a leave or enter the population. Compare with closed population.

open-access resources Natural resources (such as water and air) that are collectively owned by society at large and available for everyone to use. Compare with common-pool resources.

OpenStreetMap A crowdsourcing GIS data project that uses either XML-based file formats or smaller, more efficient formats called Protocol Buffer Binary Formats.

option value The value placed on an individual’s willingness to pay for maintaining or preserving an ecosystem service so that it can be used for benefit at some time in the future. Also called insurance value.

order Unit of taxonomic classification; an order includes one or more related families.

organic farming Farming practices that generally prohibit the use of genetically modified organisms (GMOs) and synthetic inputs (chemical fertilizations and pesticides) while allowing organic fertilizers and pesticides.

overexploitation The harvesting of a natural resource at a rate faster than it can be regenerated, resulting in decline or loss of the resource. The term applies to resources like populations of wild plants and animals (medicinal plants, game animals, fish), whole ecosystems (e.g., grazing pastures), and resources that are required to sustain life (e.g., aquifers). Also called overharvesting.

overharvesting See overexploitation.


PADDD (protected areas downgrading, downsizing, and degazettement) “ Unprotecting” conservation and other protected areas in response to social pressure from local communities that are angry they had not been fairly compensated for the loss of their lands and livelihoods, or from those that argue greater access to and use of natural resources is needed for economic development.

paleoendemic An ancient species that has a narrow geographical range and is not closely related to extant species.

parasites Organisms that live in or on a host organism, feeding on its tissues or body fluids but without necessarily killing it (e.g., ticks, tapeworms).

participatory design See co-design.

patch mosaics See landscape mosaics.

patch occupancy The proportion of habitat patches in a landscape that are occupied by a species at a given time. Metapopulation models are used to predict changes in patch occupancy across a landscape.

pathogens Organisms that attack and significantly damage the cells of another organism, often resulting in the death of the host organism (e.g., rusts, which are fungi that damage many crop plants; and Plasmodium, the protist responsible for malaria in humans.)

Pathway to Canada Target 1 Canada’s nation-wide initiative to develop a plan to achieve its international biodiversity commitment to conserve at least 17 percent of its land and freshwater by 2020 through a coordinated network of protected areas.

phenogram Diagram depicting relationships among species based on their overall similarity or dissimilarity in functional traits, without regard to the evolutionary history of the species. Compare with phylogenetic tree.

phenology Life-cycle events (e.g., reproduction, migration) that plants and animals exhibit seasonally, annually, or interannually. Climate change can impact the fitness of species by altering the timing of phenological events.

phenotype The morphological, physiological, anatomical, and biochemical characteristics of an individual that result from the expression of its genotype in a particular environment.

phenotypic plasticity The ability of one genotype to produce more than one phenotype when exposed to different environments.

phenotypic variation The different morphological, physiological, and biochemical characteristics of individuals in a population. Phenotypic variation is the result both of genetic diversity and the environmental conditions under which an individual’s genotype is expressed.

phylogenetic diversity A measure of biodiversity that incorporates phylogenetic differences among species—that is, that considers the amount of genetic differentiation between two or more species that has occurred since their divergence from a common ancestor.

phylogenetic tree A branching diagram showing the evolutionary relationships among species based on similarities and differences in their genetic characteristics. Species on the same branch of a tree have a common ancestor, and species that are closer together have a more recent common ancestor than those that are farther apart on the tree.

phylum (plural, phyla) Large unit of taxonomic classification containing related classes of species.

polymorphism A common measure of genetic diversity in a population. It is often quantified as the fraction of gene loci in which alternative alleles of a gene occur (i.e., that are polymorphic).

population A geographically defined group of individuals of the same species that mate and otherwise interact with one another. Compare with metapopulation.

population asynchrony Occurs when populations fluctuate through time in a manner that is out-of-phase. Asynchrony can maintain the temporal stability of an ecosystems service by ensuring that decreases in one population and the services it provides are compensated by increases in another population that can maintain those services.

population bottleneck Occurs when a population is greatly reduced in size due to stochastic or anthropogenic events. The loss of rare alleles and general reduction in heterozygosity usually reduces overall fitness of the population. Compare with founder effect.

population decay A chronic decline in a species’ populations size and geographic range that increase its risk of extinction.

population viability analysis (PVA) A risk-assessment process aimed at determining the minimum viable population (MVP) and minimum dynamic area (MDA) required to conserve a threatened species.

portfolio effect Occurs when each species responds differently to changing conditions through time, allowing the total amount of an ecosystem service delivered by the community to remain stable through time.

positive interactions Interactions among species that allow diverse communities to be more efficient and productive.

predators See higher consumers.

preservationist ethic One of three environmental philosophies that shaped conservation policies in the United States and elsewhere. This conservation ethic is based on a belief that large, unmodified areas of wilderness should be conserved for their intrinsic value. Its most prominent proponent was John Muir, who was instrumental in designating several national parks in the U.S. See also resource conservation ethic, and evolutionary-ecological land ethic.

primary (1°) consumers See herbivores.

primary (1°) producers Green plants, algae (including seaweed), cyanobacteria, and photosynthetic protists that can produce their own food (energy) directly from the sun via photosynthesis. Also known as autotrophs.

primary productivity The production of biomass by autotrophs (primary producers), such as green plants, algae, and cyanobacteria, which obtain their energy directly from the sun via photosynthesis.

prisoner’s dilemma A common example of a social dilemma from the field of game theory that illustrates why imperfect information causes two rational individuals to not cooperate with each other even when it is in their best interest to do so.

producer surplus The difference between the total amount earned from a product or service (price × quantity sold) and the cost of production. Compare with economic surplus.

production function method An economic analysis that estimates the value of an ecosystem good or service by modeling the values of the good or service as a function of the inputs that control it (e.g., the contribution of a mangrove wetland ecosystem to a shrimping industry).

productive use value Direct use value assigned to products that are sold in markets. Compare with consumptive use value.

propagule pressure The number of colonizing individuals of a species arriving to a new location.

propagule rain model See mainland–island model.

protected area A clearly defined geographical space that is recognized, dedicated, and managed to achieve long-term conservation of nature, including biodiversity and the many goods and services associates with the world’s different ecosystems. Protected areas include a variety of nature reserves, wilderness areas, national parks and monuments, habitat/species management areas, protected landscape and seascapes, and mixed use habitats that promote sustainable use of natural resources. Protected areas are established and maintained by governments, indigenous societies, private individuals, conservation organizations, and research institutions.

protected area network A collection of protected areas that represent all scales in the biological hierarchy (genes, species, communities, and ecosystems), and which are connected within a landscape and managed collectively. Also called a reserve network.

provisioning services Products people obtain from ecosystems.


radiative forcing The difference between sunlight absorbed by the Earth and energy radiated back to space.

rapid evolution Changes in allele frequencies that lead to adaptive responses of organisms, or even formation of new species, on short time-scale of one, or just a few generations.

Red Data Books Compilations of lists of endangered species (Red Lists) by taxonomic group and country prepared by the IUCN and other conservation organizations.

Red List Index An indicator of the changing state of global biodiversity. It defines the conservation status of major species groups, and measures trends in extinction risk over time.

Red List of Ecosystems A listing of ecosystems that are at increasing risk of collapse, from vulnerable, to endangered, to critically endangered. Being developed by the IUCN, which plans to have a comprehensive evaluation of all the world’s ecosystems by 2025.

refugia Term used to describe the equatorward areas to which some boreal species were able to retreat and thus survive the climate changes associated with the Last Glacial Maximum. Now being applied to poleward shifts that may enable species to survive the current warming climate.

regulating services Benefits people obtain from the regulation of ecosystem processes, which helps reduce harmful variation and provide a form of insurance to human well-being.

reinforcement Release of individuals into an existing population to increase its size and genetic diversity. Compare with introduction; reintroduction.

reintroduction The release of captive-bred or wild-caught individuals into ecologically and historically suitable sites where the species no longer occurs. Compare with introduction; reinforcement.

relational values Value of relationships among people, between people and nonhuman organisms, and between people and the land that enhance one’s personal or cultural identity, social responsibility, and emotional well-being. Rooted in psychology and philosophy, these values are an important aspect of preserving ecosystems and biodiversity.

representative concentration pathways (RCPs) A greenhouse gas concentration trajectory adopted by the IPCC for its fifth Assessment Report in 2014. Four scenarios of future levels of radiative forcing and greenhouse gases are based on different predictions of societal and government action on controlling greenhouse gas levels and are then used to produce general circulation models.

rescue effect The rescue of a local population from extinction by the influx of immigrants from another location that has a positive population growth rate.

reserve network See protected area network.

resource conservation ethic One of three environmental philosophies that shaped conservation policies in the United States and elsewhere. This conservation ethic is based on the belief that natural resources should be used for the greatest good of the largest number of people for the longest time. Gifford Pinchot codified its three principles: (1) fair distribution of resources between present and future generations; (2) efficient use of limited resources; and (3) scientific management of resources based on the best available data. See also preservationist ethic, and evolutionary-ecological land ethic.

resurrection biology See de-extinction.

revealed preference methods A set of economic analyses that estimate the value of ecosystem goods or services by using direct observations of the amount people are willing to pay for them. Compare with stated preference methods.

Rio Declaration on Environment and Development One of three non-legally binding agreements arising from the 1992 Earth Summit, this document included 27 principles to guide the actions of both wealthy and poor nations on issues of the environment and development.

Rio Forest Principles One of three non-legally binding agreements arising from the 1992 Earth Summit, this document recognized the value of forests and provided a set of 15 principles for sustainable forest management.

risk assessment The formal process for determining the probability that an event will occur and the consequences or impact if it does occur. Compare with risk management.

risk management The suite of tools, techniques, and policies that can be used to mitigate the risks identified in a risk assessment.

romantic transcendentalism Philosophy that arose in North America, notably with Ralph Waldo Emerson and Henry David Thoreau, viewing nature as imbued with the divine and thus a temple that provides spiritual nourishment as well as material needs. Importantly, these philosophers believed that nature required protection from the impacts of industrialism and other manifestations of human greed.

royal menageries Large collections of exotic animals historically kept by aristocrats or royal courts within palace gardens for the purpose of entertainment and as a display of wealth and power.


secondary extinction An extinction linked to the prior extinction of another species. A series of such extinctions triggered by the loss of a keystone species is an extinction cascade.

seed bank An ex situ storage facility for seeds collected from wild and cultivated plants, for use in conservation and agricultural programs.

selection effect A biological mechanism that can improve ecosystem services. When a community consists of a larger variety of species, one or a select few species are likely to be extremely efficient and come to dominate the ecological processes that generate ecosystem services.

seventh generation principle A philosophy, attributed to the Iroquois Confederacy of North America, that the decisions we make today should guarantee a sustainable world seven generations into the future. See also intergenerational sustainability.

Shapefile A GIS file format used by the Environmental Systems Research Institute (ESRI) ArcView software. The Shapefile format is made up of files with the same name but different extensions.

shifting cultivation Farming method in which farmers clear land by cutting down and/or burning trees, plant crops for a few years, and then abandon the site when soil fertility declines. Also called slash-and-burn agriculture.

sink population A local population in a low-quality habitat that has a negative population growth rate, and which would go extinct if not for immigration from a source population.

slash-and-burn agriculture See shifting cultivation.

social dilemmas Situations in which individuals make decisions in their own self-interest that have inferior outcomes compared to what they would have achieved by cooperating with others. See assurance dilemma, game theory, prisoner’s dilemma, tragedy of the commons.

source population A local population in a high-quality habitat that has a positive population growth rate, and which serves as a source of colonists to other local populations.

source–sink dynamics Term used to describe the immigration and emigration of individuals across a landscape with source and sink populations.

spatial turnover The change in biodiversity among different communities or ecosystems across a geographical landscape. See also temporal turnover.

species The base unit of classification and taxonomic rank of an organism. Species represent fundamental units of evolution, and are the primary targets of much conservation legislation. Recognizing and defining a species can be approached in several ways. See biological species concept, evolutionary species concept, morphological species concept.

Species360 An international nonprofit organization that maintains an online database of wild animals that are under human care.

species distribution models (SDMs) Predictive habitat distribution models, and range mapping that use computer algorithms to predict the distribution of a species across geographic space and time using environmental data. SDMs are often used to predict how species (including alien species) shift their range distributions in response to some form of environmental change (e.g., global warming). When the predictor variables of these correlations are climatic, the models are called climate envelope models. Also called ecological niche models.

species diversity The variety of species that comprise a biological community; the collection of species that occupy and interact in a particular location.

species revivalism See de-extinction.

species richness (S) The number of unique species observed in an ecological community or other sampling space such as an ecosystem.

Species Survival Plan (SSP) A plan that establishes breeding goals and management recommendations to achieve the maximum genetic diversity and demographic stability for a species managed in ex situ facilities.

stage-based models Population growth models that estimate growth parameters by a meaningful life-stage, which may or may not be associated with age (e.g., insect developmental stages like larva vs. adult, or small- vs. large-sized trees). Compare with age-based models.

stated preference methods A set of economic analyses that are used to estimate the value of ecosystem goods and services by directly surveying consumers to ask about their willingness to pay (WTP) for the good or service, or about their willingness to accept compensation (WTAC) for doing without them.

stepping stones Discontinuous pieces of habitat that fill in gaps between two protected areas and help facilitate dispersal. Compare with habitat corridor.

stochastic model A population model that accounts for variation in parameters such as birth and death rates by randomly drawing values from probability distributions. Compare with deterministic model.

Strategic Plan for Biodiversity (SPD) A 10-year plan adopted in 2010 by parties to the United Nations Convention on Biological Diversity (CBD) giving a framework for action by all countries and stakeholders to safeguard biodiversity and the benefits it provides to people. The SPD contains 20 goals called the Aichi Biodiversity Targets.

structured decision making (SDM) An approach for systematic and organized analysis of natural resource management decisions that integrates objective evidence-based views with subjective value-based views.

supporting services Ecological processes that control the functioning of ecosystems and production of all other services.

surrogate market techniques A set of economic analyses that are used to estimate the value of ecosystem goods and services that do not have a real-market value, but which can be estimated from “surrogates”—products or services, such as travel and housing costs, that are quantified in real markets. See travel cost method; hedonic pricing method.

surrogate species Species that provide a means for achieving broader conservation goals. The two main types of surrogate species are flagship species and umbrella species.

sustainable development Development, economic or otherwise, that meets the needs of the present generation without compromising the ability of future generations to meet their own needs. To qualify as sustainable development, projects must balance three pillars of development: economic, social, and environmental.

Sustainable Development Goals (SDGs) Seventeen broad social, humanitarian, and ecological goals that expand on the eight Millennium Development Goals and aim to complete what they did not achieve The SDGs encompass goals for improving health and education; reducing poverty, hunger and inequality; tackling climate change; and working to preserve life on land and in the sea. Each SDG includes a set of specific targets, for which progress can be measured by monitoring a set of indicators.

sustainable forest management The management of forests so that they provide for present timber needs while being maintained at population levels that will sustain their use by future generations.

sustainably intensified farming Farming that uses practices from agroforestry, conservation agriculture, and biological pest control to promote favorable ecological interactions that produce a low-input, resource-conserving agroecosystems.


2030 Agenda for Sustainable Development A United Nations blueprint, formulated in 2015, for achieving human well-being and equality while transitioning to sustainable use of the planet’s natural resources. Articulates 17 Sustainable Development Goals.

taxonomists Scientists involved in the identification and classification of species.

taxonomy The science of identifying and classifying living things.

technocentrism An extreme form of anthropocentrism holding that humans should aspire to dominate nature through technology, with the goal of controlling the global environment to suit human needs and maximize human prosperity.

temporal turnover The change in biodiversity in a community or across a landscape between any two points in time.

theory of island biogeography A theory proposing that the number of species on any island is determined by a balance between the rate at which new species colonize the island, and the rate at which populations of species that are already established become extinct. The theory is often used in conservation to predict how habitat destruction will influence species diversity, and to design protected area networks.

tragedy of the commons A social dilemma where individuals who use a shared resource act independently and according to their own self-interests, yet the collective action of many individuals pursuing their own self-interests causes them to deplete or spoil the resource, to the detriment of all.

Ftrailing-edge contraction See warm-edge contraction.

trait-based risk assessment Assessments of potential alien species that use measurable life history traits and other biological characteristics (genetic, morphological, etc.) to try to predict their introduction, establishment, and spread.

translocation See introduction.

transport vector The means by which an alien species is either intentionally or accidentally transported to a new location. Humans are the transport vector for most invasive species.

travel cost method An economic analysis that quantifies the ecosystem services of visited sites, based on the travel and time costs that individuals incur to visit the sites.

traveling menageries Touring groups of showmen and animal handlers who historically visited towns and cities with collections of common and exotic animals for the purpose of public entertainment.

trophic cascade An ecological phenomenon triggered by the addition or removal of top predators to a food web, which then leads to reciprocal changes in the relative populations of predators and their prey. Trophic cascades can produce powerful indirect interactions that can alter the properties of entire ecosystems.

trophic pyramid A graphical depiction of the amount of biomass in, or energy available to, each trophic level in a community. The amount of energy available for reproduction and growth usually declines with each successive trophic level, so the effect looks like that of a pyramid with primary producers forming a large base that supports sequentially smaller levels of consumers.


umbrella species A species whose existence benefits other species living under its protective “umbrella.” Protecting an umbrella species (such as wildebeest in East Africa) benefits many other, interconnected species.

United Nations (UN) An international, intergovernmental organization of 193 countries founded in 1945 to help maintain international peace, foster friendly relations among nations, and achieve international cooperation.

urban ecology The scientific study of the relation of living organisms with each other and their surroundings in the context of an urban environment.

utilitarian value See instrumental value.


voluntary transaction A monetary transaction that takes place only when it is considered beneficial by both parties involved.


warm-edge contraction Contraction of a species’ historic geographic range because regions that were once within that range have become too warm. Also called trailing-edge contraction.

wild meat See bushmeat.

willingness to accept compensation (WTAC) Response elicited in stated preference methods of estimating the value of ecosystem goods and services, as participants are asked how much they would be willing to accept as compensation for doing without a service.

willingness to pay (WTP) Response elicited in stated preference methods of estimating the value of ecosystem services, as participants are asked how much they would be willing to pay for a service or suite of services.

World Bank An international financial institution that provides loans and grants to the governments of poorer countries for the purpose of pursuing capital projects. Among other activities, the World Bank finances certain types of global development projects that are intended to be congruent with the UN’s Sustainable Development Goals.

World Commission on Environment and Development (WCED) See Brundtland Commission.

World Ocean Assessment (WOA) A regular process set up in 2004 by the United Nations General Assembly to review the environmental, economic, and social aspects of the world’s oceans and seas.


zoo A facility in which animals are housed in human-built enclosures and displayed to the public and in which they may also breed. Also called animal park or zoological park.

zoological park See zoo.

zoonotic diseases Infectious diseases transmitted to humans by animals.

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