Biodiversity indicators or bioindicators: useful examples for transmission grid operators

These indicators can be descriptive, performance-related, efficient or effective. However, the most important thing is that they enable us to monitor, learn, decide and act successfully.

This article will present three studies on the development of biodiversity indicators and bioindicators for high-voltage power lines in operation and under construction. These studies will add to the knowledge that is still fragmentary in this field. Furthermore, they engage towards positive contribution.

The first case study focuses on an indicator called Flor'Elec, to report on the state of plant biodiversity potential under power lines and its response to vegetation management practices.

RTE is responsible for managing the vegetation under high-voltage lines in forested areas in

France. This is usually done by clearing undergrowth and felling trees to avoid power cuts and to limit the risk of fire, thus creating open trenches in these forest habitats. Since 2012, RTE has also been developing alternative management practices (mowing, grazing and installation of tiered edges) in partnership with different stakeholders (farmers, foresters, managers of natural areas). The qualitative biodiversity indicator Flor’Elec has been developed to be easily used by non-expert agents to monitor changes in biodiversity potential in these linear elements, and thus guide development of a better vegetation management policy.

The second case study called Bat'lignes focuses on the development of a method for quantifying the effects of vegetation management methods for forest rights-of-way on biodiversity. This study is based on the relative abundance of two taxa: bats and enserial orthopterans

(bushcrickets). This method is founded on a national repository of bat activity, thanks to the development of a standardised protocol (Vigie-Chiro, natural History Museum of Paris).

Another work in progress is looking at bat activity in electrical substations that have been programmed to stop using herbicides. Here, the activity and abundance of these flying mammals are being measured before and after the electrical substations are switched to zero use of phytosanitary products.

The final case study looks at the effects of the construction and operation of undersea electricity connections. As part of the development of marine renewable energy (MRE) projects, the number of submarine power cables is increasing, with their potential impact on marine biodiversity. The OASICE project involved developing and testing a bio-indicator based on the biological knowledge of the scallop, Pecten maximus. The study focused on its ability to assess disturbances linked to turbidity and noise produced during and after the installation of submarine power cables on the seabed.

These three case studies provide an overview of the indicators that are becoming increasingly important for energy transmission operators.