Een actualisatie van de verspreiding van de Nederlandse libellen
Brachytron , Volume 11 - Issue 2 p. 103- 198
Bouwman, J.H., V.J. Kalkman, G. Abbingh, E.P. de Boer, R.P.G. Geraeds, D. Groenendijk, R. Ketelaar, R. Manger & T. Termaat, 2008. An update of the distribution of dragonflies in The Netherlands. Brachytron 11(2): 103-198. Dutch dragonflies are winners, the number of observers and the number of records keep increasing and in addition many of the species are also showing an increase. The latter is largely due to the improved water quality and the climate change which is favoring many southern species. As a result the distribution patterns shown in the book ‘The Dutch Dragonflies' (NVL, 2002) are already out-dated. The 10 year anniversary of the Dutch Society for Dragonfly research (NVL), the 25 year anniversary of the Dutch Butterfly Conservation and the 33 1/3 anniversary of the European Invertebrate Survey Netherlands was used as an nice excuse to make a new overview of the Dutch dragonfly fauna. This review deals with 67 species. Four species known only from records prior to 1990 are not discussed (Coenagrion mercuriale, Nehalennia speciosa, Epitheca bimaculata and Oxygastra curtisii). The distribution of the species is presented for two periods: 1990-1997 and 1998-2007. The first period is the same as in the book ‘The Dutch Dragonflies’ (NVL, 2002). About three times the number of records was available for the second period (308.000) compared to the first (101.000). The increase shown by many species can partly be explained by the increase in records. However many species now occur in areas where they were absent in the first period although these areas were well investigated during that period. This shows that the increase of these species is genuine and not merely a artifact of the increased research activity. Besides maps also a histogram of the flight-period for the period 1998-2007 is given. The histogram is based on unique records (a species, on one day in a square kilometer). The recorded numbers have therefore no influence on the histogram. The text of each species discusses the distribution, habitat and flight-period but the latter two only when new information became available since the publication of the former atlas (NVL, 2002). The Dutch Butterfly Conservation and Dutch Statistics Netherland (CBS) are organizing the Dutch Dragonfly Monitoring Scheme since 1998. In this project dragonflies are counted largely by volunteers using a standardized method. This has made it possible to calculate trends for 33 of the 67 species. For these species also a trend graphic is presented.
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Jaap H. Bouwman, Vincent J. Kalkman, Gerard Abbingh, E. Peter de Boer, Rob P.G. Geraeds, Dick Groenendijk, … Tim Termaat. (2008). Een actualisatie van de verspreiding van de Nederlandse libellen. Brachytron, 11(2), 103–198.
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