This glossary provides definitions for key terms used throughout the Biodiversity & Infrastructure Handbook, supporting consistent understanding across disciplines such as ecology, engineering, transport planning and policy.
Definitions are based on legal texts, reference documents and expert agreement, and cover essential concepts related to wildlife and traffic, habitat fragmentation, ecological connectivity, mitigation measures, monitoring, green infrastructure and nature-based solutions. The glossary helps practitioners interpret technical guidance and supports clear communication between stakeholders involved in infrastructure projects.
If you are new to transport ecology or working in a multi-disciplinary team, the glossary can serve as a quick reference before exploring detailed handbook chapters. Terms will continue to evolve as the handbook is updated through expert collaboration and user feedback.
Last update: October 2023 – How to cite
There are currently 26 names in this directory beginning with the letter E.
Earth berm
A constructed mound of earth, usually along a road or railway, to provide a visual screen or absorb sound. See also ‘Berm’.
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'.
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.
Ecotope
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'.
Edge
The portion of an ecosystem near its perimeter, where influences of the surroundings prevent the development of interior environmental conditions.
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).
Embankment
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'.
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'.
Escape-device
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’.
Evaluation
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.