Basisrapport Rode Lijst Libellen 2011 volgens Nederlandse en IUCN-criteria

Termaat, T. & V. J. Kalkman, 2012. Odonata Red List Report 2011 using Dutch and IUCN criteria. Brachytron 14(2): 75-187. In this report a proposal is published for a revised Red List for Dragonflies. When the Dutch Ministry of Economic Affairs, Agriculture and Innovation (EL&I) publishes this list in the government gazette, the Red List of 1997 will be replaced. In addition, this report presents a regional Red List following the internationally used criteria of IUCN, so that the situation in The Netherlands can be compared with that in other countries. All 65 species regularly reproducing in The Netherlands were assessed in order to decide whether they should be red-listed according to the criteria of the Dutch government. Red List species are species that became extinct after 1900 and species that are threatened. The threatened species are subdivided in four categories. The results are shown in figure 57. The 2011 Red List includes the following numbers of species per category: -5 Extinct in The Netherlands -4 Critically endangered -6 Endangered -6 Vulnerable -2 Susceptible Thus, the Red List comprises 23 species (35% of the assessed species). The other 42 species are Not threatened at present. In order to make a clean comparison between the new Red List and the 1997 Red List, the latter has been reconstructed using the current improved method and partly with additional data. The reconstructed 1997 Red List comprises 27 species (44% of the assessed species). These are categorised as follows: 8 species Extinct in the Netherlands, 4 Critically endangered, 8 Endangered, 6 Vulnerable en 1 Susceptible. The other 34 species were Not threatened at present. A comparison between both Red Lists shows a fairly positive picture. The 2011 Red List includes three species less than the 1997 list, despite the fact that four species appear on the Red List for the first time (two of which after becoming recently established). Three species previously extinct in The Netherlands have reappeared. And most species of running waters and fens show a positive trend. Species of softwater lakes are increasing too, but alarming exceptions exist. According to the IUCN criteria, which chiefly assess the situation over the past ten years, 19 species feature on the Red List. These are categorized as follows: – 3 Regionally Extinct – 2 Critically Endangered – 4 Endangered – 3 Vulnerable – 7 Near Threatened By IUCN criteria, the other 46 species are assessed as not threatened and belong to Least Concern. The most important causes of decline of dragonflies are habitat destruction due to intensified use of land and environmental problems such as acidification, eutrophication, and desiccation. These threats were strongest in the period 1950-1980. Most habitatspecialised species had their strongest decline during those years. From the 1990s onward many species have reversed their negative trend, due to improvement of the environment and nature restoration measures. The higher number of warm summers has also had a positive influence on some species. Potential negative effects of climate change on northern and northeastern dragonfly species are still insufficiently known. To enable Red List updating, the data collected by volunteers within the framework of distribution research and the Dutch Dragonfly Monitoring Scheme are indispensable.