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 7 names in this directory beginning with the letter T.
Target species
A species or group of species that is the subject of a conservation or mitigation action or the focus of a study.
Taxon
Category in the Linnean classification of living organisms, e.g. species. The plural from is 'Taxa'.
Terrestrial
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'.