This web application is associated with the project "POLLUM: Création d'un outil d'aide à la définition de la trame noire à partir d'images satellites nocturnes à très haute résolution" (POLLUM: Tool for the definition of a dark infrastructure from very high-resolution night-time satellite images) funded by the Occitanie region and led by La Telescop and INRAE Montpellier, and to the article "Planning sustainable lighting for biodiversity and society" ([1]). The objective is to develop and evaluate a methodology for identifying the "Trame noire" (Dark infrastructure). To this end, three analysis were carried out: analysis of (i) light pollution and (ii) ecological stakes, led by La Telescop supported by three naturalist associations (OPIE, LPO and Groupe de Chiroptère du Languedoc Roussillon), and (iii) an analysis of social acceptability of mitigation measures coordinated by INRAE Montpellier (UMR TETIS). The report ([2]) (in french) is available here.

The web app is complementary to the project report, enabling easier, more flexible and user-friendly visualization of the results. It is composed of four tabs:

• The first tab, "Light pollution indicator", includes different indicators of light pollution estimated from satellite remote sensing, using very high-resolution RGD images acquired from the Jilin-1 satellite of the Montpellier Metropolitan Area in the year 2022 on cloud-free nights. You can visualize two indicators, detailed in section II.B.3 of [2] and 2.1. of [1]: (i) the level of upward emission on a 1 metre grid, and (ii) the estimated number of visible light sources within a radius of 500m and 100m (used for assessing the impact of light pollution on dispersion for insects and bats respectively).

• In the second tab, "Ecological Indicators", you can visualize maps of ecological stakes related to light pollution in the Montpellier Metropolitan Area (MMA) (section 2.2 of [1]). Six groups of species particularly sensitive to light pollution are represented: nightjars, amphibians, insects living in wetlands, lampyridae and two bats genera: Myotis spp and Rhinolophus spp. For each groups of species, you can view (i) the predicted impact of light pollution on dispersion according to ecological stakes (evaluated in the absence of light pollution) (Section V.A.1 of [2]), and (ii) on biodiversity reservoirs (Section III.B of [2]). The application does not allow visualization of the impact of light pollution on dispersion of amphibians due to the few number of impacted zones. It does not allow neither visualization of biodiversity reservoirs for bats (Rhinolophus spp and Myotis spp) due to the confidentiality of the data. Additionally, this tab provides global indicators of ecological stakes. The "overall score" is derived from the combination of ecological stakes without light pollution (high or moderate), functionality loss of potential in reservoirs and dispersion areas (high, moderate, or low), and the number of affected species groups (from 1 to 2 or from 3 to 6). "Priority areas for light pollution mitigation policies" corresponds to the same indicator allocated to the relevant light-emitting point (Section V.C.1 of [2]).

• The third tab, "Socio-economic indicators", corresponds to the social acceptability indicators of public lighting extinction (Section IV.D of [2]) (based on two publications, [3] and [4]). The indicators correspond to an average "acceptability score" per IRIS (i.e., an infra-municipal level) for two policies: light extinction from 1 a.m. to 5 a.m. and from 11 p.m. to 6 a.m. (Table 1)

• The last tab "Summary map", allows visualization of a synthesis map of ecological and social acceptability of light pollution mitigation measures. It displays bivariate maps of the social acceptability score (either for extinction from 1 a.m. to 5 a.m. or for extinction from 11 p.m. to 6 a.m.) and the previously described overall ecological indicators "Priority areas for light pollution mitigation policies", either for high or moderate ecological stakes without light pollution (Figure 1).

Sarah Potin & Julie Chaurand (La Telescop)

Léa Tardieu (INRAE, TETIS and CIRED), Chloé Beaudet, Maia David (AgroParisTech, PSAE) & Léa Mariton (CESCO, MNHN)

[1] Tardieu L, Beaudet C, Potin S, Chaurand J, Mariton L, David M (submitted). Planning sustainable lighting for biodiversity and society.

[2] Potin S, Chaurand J, Beaudet C, Tardieu L. POLLUM : Création d'un outil d'aide à la définition de la trame noire à partir d'images satellites nocturnes à très haute résolution : Rapport Final. La TeleScop; INRAE. 2024, 66 p.

[3] Beaudet C, Tardieu L, David M (2022). Are citizens willing to accept changes in public lighting for biodiversity conservation? Ecological Economics 200, 107527, https://doi.org/10.1016/j.ecolecon.2022.107527

[4] Beaudet C, Tardieu L, Crastes Dit Sourd R, David M (submitted). Mapping preferences derived from a choice experiment: a comparison of two methods.