This glossary includes most relevant terms used in this handbook. First version of the glossary was created during the development of the ‘Wildlife and Traffic’ handbook (Action COST 341) and it has been expanded with contributions from partners of the project Horizon 2020 ‘BISON’. Terms definitions are provided by legal texts, reference documents or by agreement between experts from both ecology and infrastructure. The organisations IENEPIARC, UIC, and ISO have also assisted and will contribute in future updates.

Last update: October 2023 – How to cite

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There are currently 264 names in this directory
Accompaniment measure
An intervention intended to be positive for biodiversity and ecosystem services, but not providing measureable gains that can be set against residual impacts. Accompaniment measures may or may not target the BES features significantly impacted by a project. Synonym: 'Addtional Conservation Actions'.
Adapted culverts
Modified pipe or box culvert that allows a watercourse and/or drainage to flow underneath transport infrastructure and includes adaptations to facilitate terrestrial wildlife crossing. These often include dry ledges or shelves to provide dry passage, which are connected to adjacent habitat. The design and landscaping at the entrances is particularly designed for the needs of wildlife, not only erosion control.
Adapted viaduct
Large structure, usually supported by pillars or arches, which carries transport infrastructure and enables the preservation of valuable ecosystems and ecological corridors below the structure. Preservation and restoration of continuous terrestrial, riparian and aquatic habitats below viaducts facilitate movement of multiple vertebrate and invertebrate species. Land uses and activities under the structure must be compatible with fauna movements and preservation of ecological connectivity. Viaducts must not be considered as wildlife passages when human disturbance or infrastructure with high traffic volume is beneath. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. Synonym: 'Landscape underpass'.
Additional Conservation Actions
See 'Accompaniment measure'.
A property of a biodiversity offset, where the conservation outcomes it delivers are demonstrably new and additional and would not have resulted without the offset. See also 'Offset'.
Agricultural (underpass or overpass)
Passageway across transport infrastructure to provide access to agricultural or forestry land, which may also be used by wildlife. See also ‘Forestry road’; ‘Cattle passage’.
Alien species
Animals and plants introduced accidentally or deliberately into a natural environment where they are not normally found. Such species can become invasive in their new environment if they start spreading and causing serious damage to native species and ecosystems. See also ‘Invasive Alien Species’.
Amphibian crossing
See 'Amphibian passage'.
Amphibian fencing
A continuous structure erected alongside infrastructure, designed to prevent amphibians from crossing and directing them to a specific crossing point. See also Amphibian crossing.
Amphibian passage
Small structures built under transport infrastructure designed specifically to provide a safe crossing point for amphibians. Often consisting of multiple underpasses in close proximity to each other. Requires effective opaque fencing to intercept the amphibians and funnel them to the crossing structures. Synonyms: ‘Amphibian crossing’; ‘Amphibian tunnel’.”
Amphibian tunnel
See ‘Amphibian passage’.
Animal Detection System (ADS)
Measure to alert drivers that a large animal is approaching the road. The system involves signs that emit flashing warnings, activated by large animal detection sensors. When an animal is detected, signs are activated warning drivers that animals may be on or near the road at that time.
Animal Vehicle Collision (AVC)
When an animal is hit by a moving vehicle. If the animal is a wildlife species also called ‘Wildlife Vehicle Collision’ (WVC). Synonym: Roadkill.
Generated and maintained, or at least strongly influenced by human activities.
Arboreal crossing structure
See ‘Tree top overpass’.
At Grade Passage
See 'Level crossing'.
Measures taken to anticipate and prevent adverse impacts on biodiversity before actions or decisions are taken that could lead to such impacts. See also: 'Mitigation Hierarchy'.
Avoidance measures
See 'Avoidance'. See also 'Mitigation'.
Balancing pond
Artificial water body fed by storm drains and surface runoff, where pollutants from the road can settle out or filter through reeds before being released into the wider drainage system.
Any structure that restricts or prevents the movement of flora or fauna.
Barrier effect
The extent to which linear infrastructure features prevent, or filter animal movement. It is a combined effect of traffic mortality, physical barriers and avoidance, which together reduce the likelihood and success of species crossing infrastructure.
Before‐After‐Control‐Impact (BACI)
Study concept design in which data is gathered before and after infrastructure or infrastructure mitigation measures are constructed. This data from areas with infrastructure or mitigation measures (impact) is compared with data obtained from areas without infrastructures or mitigation measures (control).
Horizontal ledge in an earth bank or cutting constructed to ensure the stability of a steep slope. See also ‘Earth berm’.
Best practice (BP)
A superior or innovative method, process or technique that contributes to the improved performance of an asset, activity or organization and is usually recognised as ‘best’ by peer organizations. See also ‘Good Practice’.
The richness among living organisms including terrestrial, marine and freshwater ecosystems and the ecological complexes of which they are a part. It includes diversity within and between species and within and between ecosystems as well as the processes linking ecosystems and species. Synonym: ‘Biological diversity’.
Biodiversity baseline
Specific species, habitats or ecosystems, and ecosystem services occurring at a project site, their current condition, and trends before a project commences.
Biodiversity targets
Measurable, actionable, and time-bound objectives, based on the best available science, that allow actors to align with Earth's limits and societal sustainability goals.
Biological diversity
See ‘Biodiversity’.
All organisms in a community or area.
Area which has a characteristic set of environmental conditions and is inhabited by a specific community of living organisms.
Defined area (e.g. habitat corridor or patch) which, due to the presence of linear transport infrastructure or other land use, has become a limiting factor to animal migration or dispersal.
Cuttings of woody vegetation (often left in a pile, or randomly scattered across infrastructure verges).
Buffer zone 
Vegetated strip of land intended to protect sensitive habitats, e.g. protected sites, from impacts such as pollution or disturbance from infrastructure.
Buidling Information Modelling (BIM)
A digital form of construction and asset operations. It brings together technology, process improvements and digital information to radically improve client and project outcomes and asset operations. BIM is a strategic enabler for improving decision-making for both buildings and public infrastructure assets across the whole life-cycle. It applies to new construction projects; and crucially, BIM supports the renovation, refurbishment, maintenance and decommissioning of the built environment – the largest share of the sector.
Business Processing Modelling
Consists in modelling the workflow which have to be managed during the project life-cycle. In particular, these models can describe actor interactions, data life-cycle and interoperability management.
Highway route that passes around a congested town, village or other sensitive/vulnerable area.
Canopy bridge 
See ‘Tree-top overpass’.
One of the two sides of a motorway or other large road, used by traffic moving in the same direction.
Catchment area 
Geographical area from which all precipitation flows to a single stream or set of streams (may also be termed as drainage basin, or watershed). In this handbook this may also refer to the area from which animals come to use a particular fauna passage.
Overhead wires which support the contact wire on overhead line equipment in a railway.
Cattle grid
Ditch transversal to the road covered by metal bars which allows cars to pass over but prevent cattle and also some other species of wildlife to cross it. Usually installed when roads create openings in fences to avoid animal access into the fenced area.
Cattle passage
See ‘Drove road’.
Central reservation
See ‘Median’.
Cuttings from herbaceous vegetation.
Cluster (roadkill cluster)
Road stretches with aggregations of animal vehicle collisions or road kills, stretches with a greater number of occurrences than would be expected by chance. Synonym: ‘Hotspot’. See also ‘Animal vehicle collisions’.
Community (biotic)
Assemblage of interacting species living in a given location at a given time.
In terms of biodiversity, compensation involves measures to recompense, make good or pay damages for loss of biodiversity caused by a project. It differs from offsets in that compensation can involve reparation that falls short of achieving no net loss. See also 'Offsets' and 'Accompaniment measures'.
Compensatory measure
Measure or action taken to compensate for a residual adverse ecological effect which cannot be satisfactorily mitigated. See also 'Mitigation'.
See ‘Ecological connectivity’.
Conservation banking
A market where the credits from actions with beneficial biodiversity outcomes can be
Third phase of the infrastructure life cycle. It is when the infrastructure is physically built. The construction phase is the time when the effects of infrastructure development begin to show a real impact on nature. Strict adherence to all measures set to reduce environmental impacts is therefore a key consideration of this phase. See also 'Strategic Planning','Design','Operation and Maintenance', Decommissioning'.
See ‘Ecological corridor’.
Designated or recognised place for people or fauna to cross from one side of a linear infrastructure to the other. The crossing site could be provided by an structure (overpass or underpass) or take place directly over the carriageway or railway. See also 'Wildlife Crossing' 'Wildlife Passage'.
The intersection of two or more roads. Synonym: ‘Junction’.
Buried pipe, box or channel structure, that allows a watercourse and/or a transport infrastructure drainage feature to pass under infrastructure.
Cumulative effects
The increasing impacts resulting from the combination of effects from several projects or activities over a period of time. Their assessment is called cumulative effect assessment (CEA).
See ‘Kerb’.
Unitary measures of biodiversity lost, gained or exchanged. This varies from very basic measures such as area, to sophisticated quantitative indices of multiple biodiversity components which may be variously weighted.
V-shaped excavation of the land enabling transport infrastructure to be placed below the surrounding land surface.
Dark corridors
En ecological corridor that integrates mitigation of artificial light at night as an additional criterion to calculations of resistances to wildlife movement. See also 'Ecological corridor'.
The final stage in the life cycle of transport infrastructure. Few transport infrastructure projects will reach this stage in its foreseeable future, because most transport infrastructure is continuously maintained or upgraded. When radical changes in economic activities on a whole-territory scale occur, transport infrastructure can lose its importance and could be removed. See also 'Strategic Planning','Design','Construction', Operation and Maintenance'.
Deer fence
See ‘Fencing’.
Actions aimed at recovering or increasing ecological connectivity in territories affected by existing transport infrastructure. It is also used to refer to actions to mitigate any of the effects that cause habitat fragmentation (road mortality, habitats disturbances, etc.).
Second phase of the infrastructure life cycle. It starts after delimitation of the transport corridor is approved and a decision is made that allows construction preparation to start. The first subphase is the route/site selection (alignment), followed by a detailed project, contractor selection and a final building permit. During the design phase, parameters determining the potential impact of the project development on the environment, including effects on biodiversity and habitat fragmentation, are being assessed. See also 'Strategic Planning','Construction','Operation and Maintenance', Decommissioning'.
Digital Twin
A virtual representation that serves as the real-time digital counterpart of a physical object or process in the real world. DT can be deveoped for geographic areas (e.g. in urban spatial planning) or for buidg assets (e.g. in infrastructure development). See also 'Building Information Modelling'.
A wall built to prevent the sea or a river from flooding an area, or a channel dug to take water away from an area. Synonym: ‘Dyke’.
Direct effects
See 'Primary effects'.
Direct impacts
See 'Primary effects'.
Ecological process that involves the movement of an individual or multiple individuals away from the population in which they were born to another location, or population, where they will settle and reproduce.
The system of drains, pipes and channels devised to remove excess water (surface or subsurface) from an infrastructure surface.
Drover road
Traditional path for the movement of livestock that form reticular networks across regions. In some countries (i.e., Spain, Italy) they are legally regulated and protected. Synonyms: ‘Stock route’; ‘Drover track’.
Dual carriageway
Road with two lanes of traffic moving in opposite directions on either side of a central reservation (median).
See ‘Dike’.
Earth berm
A constructed mound of earth, usually along a road or railway, to provide a visual screen or absorb sound. See also ‘Berm’.
See ‘Landscape overpass’.
Ecological asset
Items of the infrastructure that have an ecological value. It includes wildlife mitigation measures preventing impacts on wildlife and enhancing traffic safety such as fencing, wildlife passages, screens, adapted illumination and wildlife traffic signs. Drainage systems, road verges and other green areas associated with the infrastructure, managed in a way that supports wildlife conservation are also included.
Ecological connectivity
Parameter of landscape function that describes the processes by which sub-populations or organisms are interconnected into a functional demographic unit. More generally, the Convention on Migratory Species defines it as the unimpeded movement of species and the flow of natural processes that sustain life on Earth which means it can also encompass other processes such as flow of water or nutrients. Synonym: ‘Connectivity’.
Ecological corridor
A geographically defined area which allows species to move between landscapes, ecosystems and habitats, natural or modified, and is intended to ensure the maintenance of biodiversity and ecological and evolutionary processes. Synonym: ‘Corridor’.
Ecological equivalence
In the context of biodiversity offsets, the term is synonymous with the concept of ‘like-for-like’ and refers to areas with highly comparable biodiversity components. This similarity can be observed in terms of species diversity, functional diversity and composition, ecological integrity or condition, landscape context (e.g., connectivity, landscape position, adjacent land uses or condition, patch size, etc.), and ecosystem services (including people’s use and cultural values).
Ecological network
A system of core habitats (protected areas, other conservation areas, and non managed intact natural areas), connected by ecological corridors, specifically designed, implemented and managed to ensure that ecological connectivity is maintained and enhanced where it is present, or restored where it has been lost. See 'Ecological connectivity'.
Ecological trap
Habitats that attract wildlife but pose hidden risks to the survival of animals. For example, attractive herbaceous vegetation near roads and railroads can increase road mortality risk for foraging animals.
Dynamic complex of plant, animal and micro-organism communities and their non-living environment, interacting as a functional unit.
Ecosystem functioning
Involves the ecological and evolutionary processes, including gene flow, disturbance, pollination and nutrient cycling.
Ecosystem services
Benefits provided to society by ecosystems. They are usually classified as provisioning (for example the production of food and water), regulation or maintenance (such as the control of climate, nutrient cycles…), and cultural, which includes the non-material characteristics of ecosystems that affect the physical and mental states of people.
Transitional zone between two habitats.
Distinct area with a recognisable set of characteristics relating to the soil, vegetation or water conditions. The ecotope represents the smallest land unit that makes up the landscape mosaic. See also 'Biotope'.
The portion of an ecosystem near its perimeter, where influences of the surroundings prevent the development of interior environmental conditions.
See 'Impact'.
Effect Zone
Strip of land both sides of an infrastructure where landscape conditions are modified by the effects of the infrastructure. The distance over which disturbances affect nature depends on topography, wind direction, vegetation, and the type of agent. The width of the affected zone is likely a magnitude larger than the physical width of the infrastructure itself. Synonym: 'Road effect zone'.
Effective mesh density
Metrics for quantifying the effective number of meshes per square kilometre, that is the density of the meshes. The effective mesh density value rises when fragmentation increases. See also ‘Effective mesh size’.
Effective mesh size
Metrics for quantifying the degree of landscape fragmentation, based on the probability that two randomly located points (or animals) in an area are connected and are not separated by a barrier (e.g. roads, urban area). The smaller the effective mesh size, the more fragmented the landscape. See also ‘Effective mesh density’.
Effective population size
The number of interbreeding adults in a population (smaller than the total population because it excludes juveniles, non?reproductive and post?reproductive individuals).
Artificial bank (made of packed earth or gravel) such as a mound or dike, constructed above the natural ground surface in a linear form and designed to carry a roadway or railway across a lower lying area.
Emerald Network
A network of areas of special conservation interest (ASCIs), which is to be established in the territory of the contracting parties and observer States to the Bern Convention, including, among others, central and east European countries and the EU Member States. For EU Member States, Emerald network sites are those of the Natura 2000 network. See also 'Natura 2000 Network'.
Endemic species 
A species confined to a particular region and thought to have originated there.
Environmental assessment
Procedure that ensures that the environmental implications of transport infrastructure development are taken into account before the decisions are made. Environmental assessment can be undertaken for public plans or programmes ('Strategic Environmental Assessment', SEA) or for individual projects, such as a motorway, an airport or a channel ('Environmental Impact Assessment' EIA).
Environmental Impact Assessment (EIA)
A process, applied mainly at project level, to improve decision making and to ensure that development options under consideration are environmental and socially sound and sustainable. EIA identifies, predicts and evaluates foreseeable impacts, both beneficial and adverse, of public and private development activities, alternatives and mitigating measures, and aims to eliminate or minimise negative impacts and optimise positive impacts. A subset of tools has emerged from EIA, including social impact assessment, cumulative effects assessment, environmental health impact assessment, risk assessment, biodiversity impact assessment and SEA. See also 'Strategic Environmental Assessment'.
Measure installed to prevent animals from becoming trapped by fences along infrastructure, e.g. badger gate, or built in the edge of a canal to enable animals to exit, e.g. escape-ramps. Synonym: ‘Fauna exit’.
A process that critically assesses, test and measure the design, implementation and results of a plan or project, in relation to its objectives. It can be conducted both qualitatively and quantitatively, to determine the difference between actual and desired outcome. In transport ecology, the aim is to check whether a project and the mitigation measures applied have met their objectives in terms of reduction of and compensation for impacts.
FAIR data
Data which are Findable (metadata and data are expected to be asey to fin by a human or machine); Accessible (once the data are found, the user easily know how to access them); Interoperable (metadata is sufficiently detailed to render the data set understandable in order to be integrated with others); Reusable (metadata is rich enough to allow for multiple reutilisation of the data set for various purposes).
Animal species.
Fauna passage
See 'Wildlife passage'.
Fauna underpass
See 'Wildlife underpass'.
See ‘Escape-device’.
A structure made of wire or other materials supported with posts that is put along linear transport infrastructure to keep animals out and eventually guide them to crossing structures. It is also installed on areas of land as a boundary to keep animals in.
Filter effect
Referred to the effect caused by the infrastructure which inhibits the movement of certain species or individuals. The scale of the effect varies between species and may even vary between sexes or age categories.
Fish passage
Modified pipe or box culvert that allows a watercourse and/or drainage to flow underneath transport infrastructure and includes adaptations to provide particular conditions that enable fish to swim through. When possible, adaptations for use by wildlife may also include dry ledges or shelves to provide passage for other terrestrial species, and which are connected to adjacent habitats.
Plant or bacterial life.
Forestry road
(Narrow) road built mainly for forestry purposes which may or may not have public access.
The breaking up of a habitat, ecosystem or landuse unit into smaller parcels.
Functional connectivity
A description or measure of how well genes, gametes, propagules or individuals move through land, freshwater and seascape. It is function of both the landscape structure and the behavioral response of organisms to this structure. Thus, functional connectivity is both specific to the species and the landscape where it occurs. See also 'Structural connectivity'.
Animals hunted for sport and food.
Game fencing
Fencing specifically for game species such as wild boar and deer. See also ‘Fencing’.
Gene flow
The transfer of alleles or genes from one population to another.
Genetic diversity
The level of variability of genetic data within a sample or population, commonly measured through metrics such as heterozygosity and allelic richness.
Geographic Information System
A conceptualised framework that provides the ability to capture and analyse spatial and geographic data. GIS applications (or GIS app) are computer-based tools that allow the user to create interactive queries (user-created searches), store and edit spatial and non-spatial data, analyse spatial information output, and visually share the results of these operations by presenting them as maps.
Good practice
A methodology, process or technique that represents an effective way of achieving a specific objective, one that has been proven to work well and produce expected results, and is therefore recommended as a model or as a useful example. See also ‘Best Practice’.
The (rate of) change of a parameter between one area or region and another.
Green bridge
See 'Landscape overpass'.
Green Infrastructure (GI)
A strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services. It incorporates green spaces (or blue if aquatic ecosystems are concerned) and other physical features in terrestrial (including coastal) and marine areas. It is also defined as ‘an interconnected network of protected land and water that supports native species, maintains natural ecological processes, sustains air and water resources and contributes to the health and quality of life for communities and people’.
Grey infrastructure
Engineered assets that aim to provide one or multiple services required by society, such as road, railways, urban areas, resource extraction, and other infrastructure.
See 'Safety fence'.
Guide fencing
Fencing built to lead wild animals to a dedicated crossing point. See also ‘Fencing’ and ‘Amphibian fencing’.
Paved channel designed to carry runoff from the edge of infrastructure into the drainage system.
The type of site (vegetation, soils, etc.) where an organism or population naturally occurs - including a mosaic of components required for the survival of a species.
Habitat attrition
Habitat destruction due to progressive damage, loss or decline in quality.
Habitat fragmentation 
Dissection and reduction of the habitat area available to a given species - caused directly by habitat loss (e.g. land-take) or indirectly by habitat isolation (e.g. by barriers preventing movement between neighbouring habitat patches).
Habitat translocation
The relocation of a habitat from one place to another usually to avoid destruction of the habitat by infrastructure development.
Habitats related to Transport Infrastructures (HTI)
Green areas associated with transport infrastructure and usually managed by transport authorities and stakeholders. These areas include verges, resting sites, water retention ponds and other drainage elements, as well as fauna passages. These areas are inhabited by many animals, plants and other organisms which find refuge, food or other resources and can potentially have either negative or positive effects on natural ecosystems and landscape surrounding the infrastructure.
Hard shoulder
See 'Shoulder'.
A close row of woody species (bushes or trees) serving as a boundary feature between open areas (often used in combination with or as an alternative to a fence).
A chemical application which kills weeds.
Major road, usually with two or more lanes in each direction. See also ‘Road’.
Hotspot (AVC hotspot/Roadkill hotspot)
See ‘Cluster’.
The effect of an external factor on an organism, species or community which may result in wider consequences at the population level. Synonym: ‘Effect’.
Measures of simple environmental variables used to denote some aspect of the state of the environment, e.g. the degree of habitat fragmentation.
Indicator species
Species indicative of (a) some current or historical environmental or historical influence (e.g. lichens can be atmospheric pollution indicators, and woodland ground-flora can be indicative of ancient woodland), or (b) a community or habitat type (e.g. some species can be used to classify invertebrate communities, or are indicative of particular habitats).
Indirect effects
See 'Secondary effects'.
Indirect impacts
See 'Secondary effects'.
The basic systems and services that allow humans to fulfil the need for transport (e.g.,roads, railways, water channels, airports and ports), energy (e.g., coal, wind, gas, solar, hydropower, waves, power lines, oil and gas pipelines), water (e.g., canals, dams), and telecommunications (e.g., internet cables).
Infrastructure life cycle
The stages that an infrastructure asset passes through during its life cycle. These phases are: 1) Strategic Planning, including Transport Policy; Strategic Transport Plan and Project Plan (Transport Area or Corridor Delimitation); 2) Design, including Area or Route Selection, Concept Design; Procurement and Detailed design (also called Constructive Project); 3) Construction; 4) Operation and Maintenance incluing adaptation and mitigation measures and; 5) Decommissioning.
Invasive Alien Species (IAS)
Animals and plants that are introduced accidentally or deliberately into a natural environment where they are not normally found, with serious negative consequences for their new environment. These species are subject to common action at a European Union level under the European regulation and included on the ‘List of invasive alien species of Union concern’. See also ‘Alien Species’.
See 'Crossroads'.
Edging (usually concrete) built along linear transport infrastructure to form part of the gutter. Synonym: ‘Curb’.
Keystone species
A species that plays a pivotal role in an ecosystem and upon which a large part of the community depends for survival.
Land cover
Combination of landuse and vegetation cover.
Land unit 
The smallest functional element of the landscape.
Land use planning
Activity aimed at predetermining the future spatial usage of land and water by society. Synonym: ‘Spatial planning’.
Natural feature on the surface of the earth.
The total spatial and visual entity of human living space integrating the geological, biological and human-made environment. It is an heterogeneous land area composed of a cluster of interacting ecosystems that create a specific, recognisable pattern. According to the European Landscape Convention, a landscape is perceived differently by local people or visitors, and evolves through time as a result of being acted upon by natural forces and humans.
Landscape diversity
The variation and richness of landscapes in a region.
Landscape element 
Each of the relatively homogeneous units, or spatial elements, recognised at the scale of a landscape mosaic.
Landscape overpass
Large structure over transport infrastructure to provide continuity of habitats from both sides. Due to their width, a diversity of habitat types (e.g. vegetation or soil types, stone rows or piles, ponds, etc.) could be included. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance by traffic when required. The main difference to wildlife overpasses is their width and possibilities for vegetation cover and diversity of habitats being created which facilitate better ecosystem connection. Landscape overpasses can also be constructed over cut-and-cover or excavated tunnels. Synonyms: ‘Ecoduct’; 'Green bridge'. See also ‘Wildlife overpass’.
Landscape underpass
See 'Adapted viaduct'.
To modify the original landscape by altering the topography and/or plant cover. This may include building earthworks to form new landscape structures.
Level crossing
A place designated for large mammals to cross a road at the same level than traffic combining fences to guide fauna to an open section equipped whith Animal Detection Systems which detect the fauna and trigger driver warnings'. Synonym 'At Grade Passage'.
Conservation (through the biodiversity offset) of the same type of biodiversity as that affected by the project. Sometimes referred to as in-kind. Several biodiversity offset policies are based on a principle either of ‘like-for-like’ or of ‘like-for-like or better’. ‘Like-for-like’ requires conservation (through the biodiversity offset) of the same type of biodiversity as that affected by the project. This is sometimes modified to ‘like-for-like or better’, in which the offset conserves components of biodiversity that are a higher conservation priority (for example because they are more irreplaceable and vulnerable) than those affected by the development project for which the offset is envisaged. This is also known as ‘trading up’.
Linear transport infrastructure
Road, railway or navigable inland waterway. Powerlines and pipelines are also included as they are designed for the transport of materials.
Major road
Road which is assigned permanent traffic priority over other roads.
In landscape ecology, the background habitat or land use type in a mosaic, characterised by extensive cover and high connectivity. See also ‘Mosaic’.
The strip of land separating the lanes of a dual carriegeway road or a motorway, which separates traffic flowing in opposite directions. Often vegetated with grass, shrubs and/or trees. Synonym: 'Central reservation'.
A set of local populations within an area, where typically migration from one local population to at least some others is necessary to sustain local population numbers. The metapopulation may have a higher persistence than the single local populations.
A set of measurements that quantifies results.
Small?scale differences in habitat.
The regular, usually seasonal, movement of all or part of an animal population to and from a given area. Usually undertaken by some species in response to changing seasons or climatic events, such as rainfall.
See 'Reduction'.
Action to reduce the severity of, or eliminate, an adverse impact.
Mitigation hierarchy
A framework for managing risks and potential impacts related to biodiversity and ecosystem services. It includes the following hierarchical but iterative actions to manage impacts: Avoid, Reduce or Minimise, Restore, and Compensate. These are often described as the four steps on the mitigation hierarchy which can also be summarised in 3 steps: Avoid, Reduce, and Compensate, when restoration actions are included as part of reduction or compensation measures.
Mobile Remote Sensing (MRS)
Any kind of sensor mounted on a mobile vector. Mobile vectors can therefore be satellites, vehicles, aeroplanes, UAVs, etc. In practice, MRS is generally deployed for specific reasons and with a specific purpose.
Mode (of transport)
“Different ways of transporting people and goods (e.g. air, road, rail, maritime, inland waters, cycling, walking, etc.).”
A process driven by the evaluation goals that combines repeated observations and measurements taken over time, usually to assess the temporal change in a parameter or in response to a disturbance/intervention or to quantify the performance of a plan/project, measure or action against a set of predetermined indicators, criteria or objectives. In the framework of transport ecology, monitoring is a key tool which begins with the design of the monitoring programme.
The pattern of patches and corridors embedded in a matrix (in this case, within a landscape). See also ‘Matrix’.
Road with dual carriageways and at least two lanes each way separated by a central reservation called ‘median’. All entrances and exits are signposted and all interchanges are grade separated.”
Pertaining to more than one 'mode' of transport.
Multiuse overpass
Structure built over transport infrastructure with multiple functions including the movement of fauna. It combines wildlife and human uses such as small forestry roads, cattle passages or pedestrian paths. Modifications are included to encourage use by wildlife such as addition of strips covered by natural materials and vegetation, and screens to reduce traffic disturbance when required. Combined with perimeter fencing that funnels the animals to the structure.
Multiuse underpass
Structure built under transport infrastructure with multiple functions including the movement of fauna. It combines wildlife and human uses such as small forestry roads, cattle or pedestrian passages. A drainage function including streams or other small waterways inside the structure is also compatible and may even lead fauna through the passage. These underpasses may include modifications to increase wildlife use such as fencing to funnel the animals, adaptation of vegetation at the entrances and measures to avoid excessive pooling of water. Combined with perimeter fencing that funnels the animals to the structure and with screens to reduce light and noise disturbance from traffic when required.
Natura 2000 network
Network of sites esignated by Member States considered to have Community importance under the Habitats Directive 92/43/EEC or classified as special protection areas (SPAs) under the Birds Directive 79/409/EEC. Together, the SPAs make up the European network of protected sites, Natura 2000. See also 'Emerald network'.
Nature-based Solutions (NbS)
Actions to protect, sustainably manage, and restore natural or modified ecosystems, that address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits.
Net Gain (NG)
The point at which project-related impacts on biodiversity and ecosystem services are outweighed by measures taken according to the mitigation hierarchy, so that a net gain results. May also be referred to as net positive impact. See 'Biodiversity' and 'Ecosystem Services'.
No Net Loss (NNL)
A goal for a development project, policy, plan or activity in which the impacts on biodiversity it causes are balanced or outweighed by measures taken to avoid and minimise the impacts, to restore affected areas and finally to offset the residual impacts, so that no loss remains. NNL must be defined relative to an appropriate reference scenario. See also 'Net Gain'.
Noise barrier
Measure installed to reduce the dispersal of traffic noise in a certain sensitive area (e.g. wall, fence, screen).
Measurable conservation outcomes resulting from actions designed to compensate for significant residual adverse biodiversity impacts arising from development plans or projects after appropriate prevention and mitigation measures have been taken. The goal of biodiversity offsets is to achieve no net loss and preferably a net gain of biodiversity on the ground with respect to species composition, habitat structure, ecosystem function and people’s use and cultural values associated with biodiversity.
Operation and Maintenance
Fourth phase of the infrastructure life cycle. It is the next stage after the process of preparation and construction. It usually lasts for decades. During this phase, the infrastructure affects its surroundings with noise and light and pollution from traffic and maintenance, and it creates barriers to movement and splits species populations. See also 'Strategic Planning', 'Design', 'Construction', 'Decommissioning'.
Structure, mainly roads or railways or other type of linear transport infrastrcuture (including its accesses) which allows vehicles, people or fauna, to cross above another transport infrastructure. See also 'Wildlife overpass'.
Paved road
A road which surface is made with asphalt, bitumen, concrete or tarmac. See also ‘Unpaved road’.
Pedestrian underpass
Structure under an infrastructure designed for use by pedestrians.
Any chemical application used to kill insects, rodents, weeds, fungi or other living organisms, which are harmful to plants, animals or foodstuffs.
Cylindrical water tight structure sunk into the ground to provide a passage (from one side of the infrastructure to another).
A forward looking strategy or design, often with co-ordinated priorities, targets, options and measures that elaborate and implement policy. Synonym: 'Plan'.
A general course of action/ direction guiding ongoing decision making towards a desired goal or outcome.
Functional group of individuals that interbreed within a given, often arbitrarily chosen, area.
Precautionary principle
A principle to guide decision?making in the absence of scientific certainty which states that precautionary measures should be taken when an activity may harm human health or the environment and that the proponent for an activity must prove that the action will not cause harm.
Primary effects
An outcome directly attributable to a defined action or project activity. They are produced by the physical presence of infrastructure, its structural design, maintenance, and use. Synonyms: 'Direct impacts', 'Direct effects'. See also: 'Secondary effects'.
A coherent, organised agenda or commitments that implements policy. Could encapsulate many projects.
Protected Areas
See 'Protection Zone'.
Protection Zone
An area of land and / or sea especially dedicated to the protection and maintenance of biological diversity, and of natural and associated cultural resources, and managed through legal or other effective means.
Public-Private Partnership (PPP)
A cooperative system made up of two or more public and private organizations, typically involved in a long-term agreement.
Red list
The IUCN Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been evaluated using a system designed to determine the relative risk of extinction. The main purpose of the IUCN Red List is to catalogue and highlight those taxa that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable). Red lists of species also exist at the national level.
Measures taken to reduce the duration, intensity, significance and/or extent of impacts (including direct, indirect and cumulative effects, as appropriate) that cannot be completely avoided, as far as is practically feasible. Synonym: 'Minimise'. See also: 'Mitigation hierarchy'.
Re-establishment of forest by the planting of trees (may have commercial or ecological functions).
A geographical area (usually larger than 100 km2) embracing several landscapes or ecosystems that share some features, e.g. topography, fauna, vegetation, climate, etc. Examples include bio-geographic and socio-economic regions.
The process of converting an existing landscape surface into a designed form by undertaking earthworks, e.g. cutting, filling or smoothing operations.
See 'Restore'.
Remote Sensing
Methods for gathering data from a distance. In environmental studies and in monitoring, it usually refers to the use of satellite or airborne sensors to examine conditions and changes over large regions or landscapescale
The ability of an ecosystem to respond to a perturbation or disturbance by resisting damage and recovering quickly.
Process of actively or passively assisting the recovery of an ecosystem towards or to good condition, of a habitat type to the highest level of condition attainable and to its favourable reference area, of a habitat of a species to a sufficient quality and quantity, or of species populations to satisfactory levels, as a means of conserving or enhancing biodiversity and ecosystem resilience.
In the context of ecological corridors, the recovery of ecological connectivity that has been diminished, impaired or destroyed. For a generic definition of restoration as an action within the Mitigation Hierarchy see 'Restoration'.
The process of rebuilding, following major human disturbance, a natural ecosystem by restoring natural processes and the complete or near complete food web at all trophic levels, as a self-sustaining and resilient ecosystem with biota that would have been present had the disturbance not occurred. The ultimate goal of rewilding is the restoration of functioning native ecosystems containing the full range of species at all trophic levels whiles reducing human control and pressures.
Right of Way (ROW)
“Strip of land over which is built a public road, rail or other infrastructure where the infrastructure operators have legal rights. Often used to refer road sides. See also ‘Habitats related to transport infrastructure (HTI)’, ‘Roadside’ and 'Road verge’.
Riparian forest
Forest situated by a riverbank or other body of water.
Concrete or tarmac public way for vehicles, humans and animals.
Road corridor
Linear surface used by vehicles plus any associated verges (usually vegetated). Includes the area of land immediately influenced by the road in terms of noise, visual, hydrological and atmospheric impact (normally within 50 to 100 m of the edge of the infrastructure).
Road ecology
See ‘Transport Ecology’.
Road network
The interconnected system of roads serving an area.
Road verge
Area adjacent to roads generally located outside the road shoulder and vegetated
Animals that have died as a result of collisions with vehicles on roads. See also ‘Animal vehicle collision’.
Area adjacent to the carriageway, generally includes the road shoulder and the road verge.
Junction where three or more roads join and traffic flows in one direction around a central island of land which is often vegetated.
Safety barrier
A vehicle-resistant barrier installed alongside or on the central reserve of infrastructure, intended to prevent errant vehicles from leaving the designated corridor and thus limit consequential damage. See also 'Safety fence' and 'Guard-rail'.
Safety fence
Continuous structure (of varied material) erected alongside infrastructure designed to prevent errant vehicles from leaving the designated corridor and limit consequential damage. Synonym: 'Guard-rail'.
In landscape ecology, the spatial and temporal dimensions of patterns and processes.
Process for identifying content and extent of the information to be submitted to the competent authority under the EIA process. Scoping is mandatory for the SEA process. See also 'Strategic Environmental Assessment'.
Secondary effects
Impacts triggered in response to the presence of the project, rather than being directly caused by the project’s own operations. They are derived from interactions among primary effects, and the interplay with environmental conditions and other driving factors at a landscape or regional level Synonyms: 'Indirect effects', 'Indirect impacts'. See also 'Primary effects'.
Service road
Subsidiary road connecting a more major road with adjacent buildings or facing properties. Normally not a thoroughfare.
Sheet piling
Waterway bank erosion protection (wooden, iron or concrete planks sunk vertically between the edge of the water and the embankment).
The linear paved strip at the side of a motorway which vehicles are allowed to use during emergencies, and which is used by maintenance vehicles to access works. Synonym: ‘Hard shoulder’.
Single carriageway
Road in which a single lane of traffic is flowing in each direction, with no barrier or median strip dividing them.
Single track road
Road that is only as wide as a single vehicle, and thus does not permit the flow of two-way traffic.
A defined place, point or locality in the landscape.
Slope protection
Activity or measure aimed at preventing soil erosion on slopes (e.g. by covering the ground with vegetation, stones, concrete or asphalt).
Small fauna underpass
Structure built under transport infrastructure designed specifically to provide a safe crossing point for small fauna such as reptiles, small mammals or invertebrates which are used to dark, humid habitats. Construction types are predominantly box or vault structures. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. Depending on underpass size, these are also suitable for larger animals. Note: to be suitable for amphibians in migration, these structures may require specific fencing. See also 'Amphibian passages'.
Source - sink habitats and populations
Source habitats are areas where populations of a given species can reach a positive balance between births and deaths and thus act as a source of emigrating individuals. Sink habitats, on the other hand, have a non-sustaining birth-death ratio and are dependent on immigration from source populations.
Spatial planning
See 'Land use planning'.
Stepping stone
Ecologically suitable habitat patch where an organism temporarily stops while moving along a heterogeneous route.
Stock route
See ‘Drover route’.
Strategic Environmental Assessment (SEA)
A range of analytical and participatory approaches that aim to integrate environmental considerations into policies, plans and programmes and evaluate the inter linkages with economic and social considerations. See also ‘Environmental Impact Assessment.
Strategic Planning
First phase of the infrastructure life cycle. It starts with the definition of general goals and vision for transport corridors, identifying the needs for transport infrastructure in a region or country, and providing specifications about priorities, location and planned schedule. This phase is divided in two subphases: i) Transport policy and, ii) Transport Strategy and delimitation of areas and corridors. See also 'Design','Construction','Operation and Maintenance', Decommissioning'.
See 'Plan'.
Structural connectivity
A description or measure of habitat permeability (how well a given habitat allows movement) based on the physical features and arrangements of habitat patches, disturbances and other land, freshwater or seascape elements presumed to be important for organisms to move through their environment. Structural connectivity is used in efforts to restore or estimate functional connectivity where measures of it are lacking. See also 'Functional connectivity'.
Surface-water drainage 
System devised to remove water from the surface of the ground (or infrastructure). See also 'Drainage'.
Target species
A species or group of species that is the subject of a conservation or mitigation action or the focus of a study.
Category in the Linnean classification of living organisms, e.g. species. The plural from is 'Taxa'.
Pertaining to land or earth.
Top soil 
The top layer of soil that supports vegetation.
Transport corridor
Areas which concentrate linear transport infrastructure, such as roads, railways, waterways or powerlines, and which may impede or facilitate movement across the landscape. See also ‘Ecological corridor’.
Transport ecology
Science that seeks an understanding of the interactions between roads/railways/utility easements etc. and the natural environment, including wildlife, natural resources, land use and climate change. Synonym: ‘Road Ecology’.
Tree-top overpass 
Rope, net or pole suspended above transport infrastructure from vertical poles or trees, for arboreal and scansorial species. While fencing would improve rates of use, fence designs are yet to be developed due to the climbing ability of the target species. Similar structures have been proposed for bats, the success of which has yet to be demonstrated. Synonyms: 'Canopy bridge'; 'Arboreal crossing structure'.
Structure (including its access points) which allows one linear transport infrastructure to pass under another. See also 'Wildlife underpass'.
Unpaved road
A road not covered by any artificial material such as asphalt or concrete. See also 'Paved road'.
Structure, mainly roads or railways or other type of linear transport infrastrcuture (including its accesses) which allows vehicles, people or fauna, to cross under another transport infrastructure. See also 'Wildlife underpass'.
The strip of land (often vegetated) beyond the infrastructure surface itself, but within the infrastructure corridor.
Long elevated bridge, typically supported on pillars, which carries a transport infrastructure over a valley or other similar low-level landscape area. The landscape below these structures can be designed to conserve or maintain continuous riparian and aquatic habitats, thereby facilitating wildlife movement. See also ‘Adapted viaduct’.
A navigable body of water.
Construction in a river or canal designed to hold the water upstream at a certain level.
Land or area containing high levels of soil moisture or completely submerged in water for either part or the whole of the year.
All wild animals, plants, fungi and bacteria collectively.
Wildlife corridor
Linear-shaped area or feature of value in facilitating wildlife movement across a landscape. See also ‘Ecological corridor’.
Wildlife crossing structure
See ‘Wildlife passage’.
Wildlife fencing
Fencing designed and erected specifically to prevent animals from gaining access onto infrastructure and to lead them to safe crossing points.
Wildlife overpass
Structure built over transport infrastructure specifically to provide a safe crossing point for wildlife and to connect habitats from both sides. The surface is covered with natural materials and soil allowing the growth of different species of vegetation. Other refuges for fauna such as stone or wood rows can also be installed. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. While similar to landscape overpasses, they are narrower, limiting the extent to which different habitats and vegetation can be included on the structure. Synonym: 'Fauna overpass'. See also 'Landscape overpass'.
Wildlife passage
Structure designed to facilitate the safe movement of wildlife across linear transport infrastructure, located over or under the infrastructure. It can be specifically designed for wildlife use or modified to combine wildlife crossing with other uses such as drainage and other. Synonyms: ‘Wildlife crossing structure’, ‘Fauna passage’.
Wildlife underpass
Structure built under transport infrastructure specifically to provide a safe crossing point for wildlife, typically large and medium-sized mammals, such as ungulates and large carnivores, but also for other vertebrates and invertebrates. Construction types are predominantly box, vault or beam platform structures. The substrate is covered with natural materials and soil allowing different species of vegetation growth where there is enough light and humidity. Elements such as stone rows may provide wildlife refuges inside. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. Synonym: 'Fauna underpass'.
Wildlife Vehicle Collisions (WVC)
See ‘Animal Vehicle Collision’.
Willingness-to-pay (WTP)
A term used in economics to quantify the maximum amount of consumption possibilities that an individual is prepared to sacrifice in order to consume a particular good. In many research projects, such as valuation of various environmental assets, the purpose is to estimate WTP in terms of money.