IENE 2016

Background: The role of linear transportation infrastructures (roads, railways, oil and gas pipelines, power lines, rivers and canals) in fragmenting natural habitats has been demonstrated. Yet, the potential of habitat or corridor of their verges (road and railway embankments, strips of grass under power lines or above buried pipelines, or waterway banks) for biodiversity remains controversial. In a context of decreasing natural habitats, the potential of anthropogenic areas for contributing to wildlife conservation should be considered. Here, we will present a systematic review on the potential of linear transportation infrastructure verges as corridor and/or habitat for insects in temperate landscapes. A systematic review is a methodology of evidence synthesis, which consists in collecting, screening, appraising and synthesizing all available evidence on a subject.

Methods: Searches for literature were made using an online publication database, a search engine and by sending a call for literature to subject experts. Search terms were developed in English. Identified articles were screened for relevance based on titles, abstracts and full texts using inclusion criteria detailed in an a priori protocol. Included articles were subject to critical appraisal of susceptibility to bias. A narrative synthesis of studies with low or medium susceptibility to bias was finally made.

Results: Our searches identified over 45,000 articles about all biodiversity. During the successive screening stages, articles about non-insect species were put aside in order to comply with the time frame of the project.  At the end of the screening stages, 165 articles about insect species remained relating to four specific synthesis questions. 140 of these articles relating to the two first synthesis questions are still being critically appraised. Of the 25 articles left relating to the two other synthesis questions, 11 were excluded during critical appraisal, leaving 14 included articles. This low number of articles did not allow to conduct a meta-analysis but a narrative synthesis was made.

Conclusions: A knowledge gap was identified regarding the role of corridor of linear transportation infrastructure verges for insects. The effect of the surrounding landscape on insect diversity of verges seems to depend on the type of landscape and on the taxa considered. On these two specific synthesis questions more studies are hence needed, in order to allow for making meta-analysis and drawing more robust conclusions.