Glossary of Key Terms

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

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There are currently 8 names in this directory beginning with the letter I.
Impact
The effect of an external factor on an organism, species or community which may result in wider consequences at the population level. Synonym: ‘Effect’.
Indicator
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'.
Infrastructure
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’.