Ground beetle (Coleoptera:Carabidae) species composition of three forests in the Netherlands

During this research the carabid fauna assemblage of two forests, the Amsterdamse Bos and Purmerendse Bos, was determined. Throughout the forests series (locations within the forests) were chosen to place pitfall traps. Each series consisted of five plastic cups that were dug into the soil in such a way that they were flush with the surface. Each cup was located five meters away from the subsequent one. The cups were filled with formaldehyde (diluted water 1: 10) as conservative and a small amount of soap in order to decrease water tension and thus let the organisms submerge. Afterwards the trap was covered with a wooden plate attached onto the soil with nails to protect it from rain and damage. The plates were covered up with plant material as camouflage. A small opening in between the soil and the plate was left so there was space for soil fauna to crawl into the cup (Picture 1). Because carabids are often dispersed throughout an area in small populations instead of being homologous spread (Raino & Niemelä, 2003) a diversity of locations was chosen. Therefore biotic and abiotic conditions were recorded (soil, light invasion, litter and dominant vegetation) to select the most diverse sites. Nine series in the Amsterdamse Bos and eleven series in the Purmerendse Bos were placed. These forests were sampled for a time span of 63 days. When traps were emptied the formaldehyde was refreshed. After the third time all of the traps were removed and holes filled up with soil. The content of emptied traps was washed with water and afterwards the ground beetles were selected and preserved in 95% ethanol. The ground beetles found were identified by making use of “De Loopkevers van Nederland & Vlaanderen” by Boeken, Desender, Drost, van Gijzen, Koese, Muilwijk, Turin & Vermeulen (2002. For each series the quantity of caught individuals was recorded. From the Eyserbos, data collected by supervisor B. Brugge in the years from 2012 to 2014 was used for analysis; during this research the same catching methods were used but the time scale was different. For four years, five series of pitfall traps were placed for one week halfway of June thus for a total of 28 days. Data of the species composition and the ecological characteristics and classification of the three forests was collected. Following classifications and ecological characters of the species that were used for analysis were documented: the status of the species in the Netherlands, Belgium, Denmark and Luxemburg, the status of the species in the Netherlands, the distribution in the Netherlands, how important the species’ population in the Netherlands is in its distribution in Europe (so called I-species), which type of habitats a species can migrate through to spread to other habitat patches, the classification of the species by Lindroth (1969), the degree of eurytopicity of the species and the flight capabilities of the species. Data obtained can be found in the file: 201703-05_groundbeetle_species_composition_Eyserbos_AmsterdamseBos_and_PurmerendseBos.txt The possible inputs for characteristics can be found in the file 201706_Legenda_data_groundbeetles_species_composition_Amsterdamse_and_Purmerendse_bos.txt