They will never see Trigance like before! For several days, residents have been crossing the village paying more attention to their strange neighbors: the little animals. Spiders, bats, aquatic insects, bees and other wild pollinators were put under the microscope of dozens of experts, volunteers and curious people for almost a year, in order to paint a portrait of the town.
The municipality had requested the Verdon Regional Natural Park (PNRV) to carry out an Atlas of municipal biodiversity. The long-awaited results were revealed to the population in mid-December. Here’s what you need to remember in particular.
The Riu, abundant source of life
Dominique Chavy is responsible for the natural heritage division for the PNRV. He has coordinated the work carried out in the village since March. The observations made it possible to identify areas rich in biodiversity: watercourses. “Until now, we had no data on aquatic insects. We were able to carry out surveys. The species are rather alpine in the streams flowing into the Jabron. The problem is that most of the streams are dry in summer. As a result, some insects have difficulty surviving. Fortunately, we have the Riu, which flows all year round. If we didn’t have it, the town would lose a lot of its uniqueness!
Several protected animals have been seen around it, including the amphibious vole and the water shrew. A little-known larva in the Var (oxycera finished) was also discovered in her bed. The fly has the particularity of having only been mentioned in three places in France for two hundred years, before its discovery in Trigance!
Jabron, epicenter of an exacerbated climate
Almost all of the municipalities adhering to the PNRV have a Mediterranean and Alpine climate. “Nevertheless, this trait is exacerbated in Trigance, to the point that Mediterranean plants are found a few hundred meters from mountain species.”
The epicenter of the phenomenon is found during the Jabron. “Its right bank is colder than its left bank.” Budding researchers have got their hands on the martagon lily (alpine)… and the pomponne lily (southern). The contrast extends to the nature of the soils (acidic, sandy, siliceous) and the diversity of landscapes, between forests and moors.
Beautiful density of large trees
Let’s talk about the forests. They amazed Dominique Chavy. “There is a nice density of large trees in different places. They may have been spared from logging. Otherwise, only the lower branches were removed in the past? This is worth digging!”
Conversely, the Scots pine (dominant in the area) suffers more in the Siounet, Chastillon and Breis massifs. “It dies back in low-lying environments due to repeated drought and heat.” The holm oak could gain surface area in the future in its place. “Still, the Scots pine is also colonizing areas again. We have seen a lot of terraces in young forests!”
Nocturnal sightings in the village
Impossible to ignore the heart of the village! Located between meadows and forests, it is therefore permeable to fauna and flora. “A harmless snake, the gerund coronella, has been seen several times near houses. The gecko is also present. Either because of global warming, or because it may have been imported during construction. It can lay eggs in concrete blocks.”
Other neighbors are invisible during the day, but noticeable at night: bats. The emblematic species of Verdon, the Lesser horseshoe bat, sometimes nests in houses. Problem: she flees the light. “The municipality turns off its street lights at 11 p.m. The ideal would be to do it earlier. The peak of activity of these animals is between 9:30 p.m. and midnight.”
Will it do so to further protect its exceptional natural heritage?
Know+
A notebook on the biodiversity of Trigance has been published by the Verdon Regional Natural Park. It is available at the town hall.
Nearly 1,900 plants, animals and insects inventoried
Since March, nine outings dedicated to the public have been organized in the town (wild salads, spiders, orchids, nocturnal insects, bees and hoverflies, aquatic insects, bats, mushrooms, etc.). Around twenty people participated on average in each workshop, also led by Nicolas Martinez, ornithologist at the PNRV. In total, 11,049 observations were carried out (a large part of which was carried out by a network of experienced volunteers). And no less than 1,877 inventoried species (1) (fauna and flora combined).
“Among them, 1,141 are new”rejoices Dominique Chavy, head of the natural heritage center for the PNRV and leader of the park’s scientific council. It is impossible to transcribe the entire list here. This can nevertheless be found in the biodiversity notebook, available at the town hall. The Biodiversity Atlas has existed since 2012. Trigance is the ninth municipality to benefit from it within the Verdon Regional Natural Park (2). In 2025, it will be Castellane’s turn.
“At the time, we were talking about a citizen inventory of biodiversity”explains Dominique Chavy. The approach is supported by the French Biodiversity Office. The objective is in particular to improve knowledge with residents.
“We often have the impression of knowing a commune. But we always discover new ones! The idea is also to raise awareness of common species. They have things to say about the environment.” The data collected is transmitted to the Natural Heritage Inventory Information System (SINP). This is also consulted by state services. “Project leaders must also take this into account when they apply for a building permit.”
1. Including 180 species of wild bees, 167 dipterans, 53 hoverflies, 134 spiders and 102 aquatic invertebrates.
2. The Municipal Biodiversity Atlas (ABC) concerns all municipalities and intermunicipalities in France. It is supported by the French Biodiversity Office (OFB). More than 3,500 cities have established an ABC to date.
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