AbstractDebbieDebbie212008-01-03T23:12:00Z2008-01-03T23:12:00Z16433539WBBS298417411.5604AbstractThe Effects of Climate Change on the Phenology of Carabid Beetles in DrentheThe Netherlands are home to the longest continuous observation programme on carabid beetles in the world. Weekly catches, done with pitfall traps, have started in 1959 in the Kraloer Heath and in 1963 in the Hullenzand. Both heath land areas in the Province of Drenthe (the north of the Netherlands). The observation programme is still active and was part of a study on the population dynamics of carabid beetles. A study started by the chairman of Foundation WBBS, Piet den Boer. Researchers from Foundation WBBS and Wageningen University have analyzed this long-term dataset on the consequences of recent changes in weather and climate on both the population size as the phenology of carabid beetles.Main conclusionsThe average temperature has increased with 1°C in the last few decades in the research areas. The total amount of precipitation has not changed significantly, the amount of hours of sunshine has however obviously increased. The change in temperature has partly occurred in different times of the year than the change in sunshine. Temperature, precipitation and sunshine, in the current and preceding year, have a great influence on the total amount of caught carabid beetles and on the start and end of the active season. There was a significant increase in the amount of beetle catches early 1990’s. A combination of soil removing and an obvious rise in temperature from the late 80’s, that lead to an increase in xerotherm species, was probably the cause of this. Almost all species show an obvious decline in numbers in recent years. Only 4 species show an increase in the amount of caught individuals as a result of increase in temperature and amount of sunshine. The other species seem to benefit most from soil removing once every 10-15 years to keep the population size on a high level. The changing climate seems to provide difficulties for northern species. Carabid species that have the Netherlands as centre of their distribution seem to maintain. Some southern species are moving up this way. Some northern species can however maintain in the same areas if the maintenance of the area is beneficial to the species. Wet, warm winters have obvious negative effects on several carabid species that are in their period of rest or are in the ground. One of these species is the severely threatened Agonum ericeti (which is a prioritized species for the Province of Drenthe). The survival changes of the carabid beetles can improve with more hours of sunshine while in the resting or ground period. The active season of only 4, out of 20 species we researched, has started significantly earlier in the period after 1988 than in the period before 1988. Carabid beetles seem to have less phenological reactions on the rise in temperature than species of plants. The role of climate variables from the preceding year is possibly partly responsible for this. Climate change seems to primarily start the active period earlier of day active species such as Carabus arvensis, Poecilus lepidus and Poecilus versicolor. A slow start of the active season can be caused by high temperatures during the winter months of the preceding year. It is possible that the carabid beetles do not get their required needs for a certain amount of cold fulfilled. The speed of development of adults seems to be increased during an active season with high temperatures and more sunshine, leading to a quicker end of the active period. Consequences for existing ecological relationships and dependences between animal- and plant species are yet unclear and have to be examined further. It is of great importance to continue the observation programme of carabid beetles in Drenthe so the effects of future climate change on nature can be monitored and explained. It is also important to continue these catching sites to research how maintenance can have a positive impact on (and on which) carabid species. In order to become a full report deposit € 12,50 into our Postbank account 8165357, Stichting WBBS, Kanaaldijk 36, 9409 TV Assen, Don't forget to mention name and adress.