Biodiversity Data Journal : Data Paper (Biosciences)
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Data Paper (Biosciences)
Occurrence data on beetles (Coleoptera) collected in Dutch coastal dunes between 1953 and 1960
expand article infoG.M. Gerrits‡,§, L. Hemerik
‡ Wageningen University and Research, Biometris Mathematical and Statistical Methods Group, Wageningen, Netherlands
§ Netherlands Institute of Ecology (NIOO-KNAW), Department of Terrestrial Ecology, Wageningen, Netherlands
Open Access

Abstract

Background

Historical field data in ecology are exceedingly rare and, therefore, their preservation and publication is of high importance, especially as these data can function as a point of reference for present day biodiversity research. Therefore, we digitised a 65-year-old dataset on ground-dwelling beetles caught with pitfall traps in the coastal dune area "Meijendel", situated in the western part of the Netherlands.

New information

The data presented in this paper has never been published in a systematic way before and has had a long journey from moment of capture to the current digitisation. From 1953 through to 1960, 100 pitfalls were active and catches were collected once a week. A total of 36,400 samples were aggregated with approximately 90,000 occurrences recorded. All captures were identified up to species level and counted and sex determined where possible. The database has been registered in the Global Biodiversity Information Facility (GBIF) and can be found under: https://www.gbif.org/dataset/9d02b439-aa5c-4c22-b1d9-d27fbde9e3ee.

Keywords

ground-dwelling beetles, historical field data, pitfalls, Meijendel, GBIF, carabids, Meijendel Research Project

Introduction

Historical field data, collected using standardised protocols, are rare in ecology. Therefore, conserving and publishing such data by means of digitisation are of high importance (Tingley and Beissinger 2009; Heberling et al. 2021), even more so because some of these datasets are documented only on paper or have been stored in professional archives and are not necessarily publicly available. Moreover, with biodiversity increasingly under pressure due to anthropogenic influences (Hallmann et al. 2017, IPBES, Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services 2019), historical datasets are potentially of much value as they can serve as past baseline for present-day biodiversity research. Therefore, when the opportunity presented itself, we decided to manually digitise a historical dataset and its associated metadata, that was collected in the coastal dune area of "Meijendel" in the Netherlands in the period 1953-1960, in order to make it available for future study.

Around 200 archival folders with specially printed paper sheets containing the data have survived several decades of departmental shuffles and relocations and finally ended up in the attic of one of the original researchers, who then passed them on to us. The species folders contain written records of all beetle species (Coleoptera) that were caught using pitfall traps from March 1953 through to March 1960 in disparate habitats of the dune ecosystem. The folders will be transferred to Naturalis Biodiversity Centre in Leiden, The Netherlands, where already a part of the specimens, upon which this dataset is based, are stored. The use of pitfalls in this study was one of the first examples of this now much used technique and was partly inspired on beetles found trapped in manholes dug by soldiers in the war (de Bruyn, personal communication). A total of 100 of these "catch cans" (vangblikken in Dutch) were specially made from metal sheets and were dug in flush with the soil surface. The dataset has only partly been analysed before (den Boer 1956, den Boer 1958, Bouman and van Hinsberg 1991a, Bouman and van Hinsberg 1991b). Year totals from this dataset were available and have been used for ecological classifications of ground beetles by Turin (Turin et al. 1991).

The pitfalls were installed as part of a large-scale study to assess the effect of water infiltration and extraction for human consumption on the fauna and flora of the area, which itself was part of a larger project that was set up before the Second World War as one of the first standardised ecological research studies designed to collect as much long-term ecological data from one specific area as possible (Schierbeek 1923, Bakker 1974). This early example of the then burgeoning science of ecology, was set up in order to find answers to basic ecological questions regarding community composition and species' interactions with their environment (Schierbeek 1923, den Boer 1956).

The Meijendel dune area, where the pitfall study was installed, is a highly heterogeneous, species-rich landscape with alternating wet dune valleys, wind-swept dune tops above desert-like barren south-facing slopes and moist, shaded north-facing slopes. The landscape forms a finely grained mosaic-like structure with sharply defined gradients. Habitats consist of open, dry, moss- and lichen-dominated vegetations, alternated by dune grasslands with Calamagrostis epigejos, Festuca spp. and Carex arenaria and several kinds of woods, groves and shrub-dominated vegetations (Boerboom 1960, Schaminee 1995).

Project description

Title: 

Occurrence data on beetles (Coleoptera) collected in Dutch coastal dunes between 1953 and 1960

Study area description: 

The study area "Meijendel" is a 20 km2 coastal dune complex running 3 kilometres inland and 7 kilometres along the coastline and is lodged between the city of The Hague in the south, the North Sea in the west, the city of Wassenaar in the northeast and adjacent dunes in the north. The water company Dunea Duin & Water manages Meijendel as a water catchment area. It is also a nature reserve enjoying protection as part of the European Natura2000 network. The area is made up of three geomorphological zones running parallel to the coastline; (1) the fore-dune complex with Ammophila arenaria dominated young sand dunes, (2) a zone dominated by parabolic dunes and (3) old dune valleys with a 19th century agricultural history (see Fig. 1). Pitfalls were placed in zone 2 and 3 in different vegetation types.

Figure 1.  

(a) Geographic location of the study area Meijendel in the Netherlands, (b) Location of the 100 pitfalls (green dots) in the Meijendel area situated within four sub-areas: "Zeeduinen" containing pitfalls 1-24; "Bierlap" with pitfalls 25-60; "Natte sprang" with pitfalls 61-75 and "Rozenbos" with pitfalls 76-100. Note that up to 1955, all of the water extraction lakes (blue areas) were absent. The lakes in the Rozenbos and Natte sprang areas were created only after the pitfall research programme was ended in 1960. For a more detailed map, see end of Suppl. material 2.

Funding: 

This project was made possible with grants from:

  1. NLBIF Netherlands Biodiversity Information Facility (grant number nlbif2020.005)
  2. Drinking water company Dunea Duin & Water.

Sampling methods

Description: 

The geographic extent of the digitised dataset (52.14018N to 52.1557N; 4.34517E to 4.36339E) corresponds with a 2 km2 area in the the north-western part of the Meijendel area.

Sampling description: 

Pitfalls were placed in groups of three in four subareas, namely Zeeduinen, Rozenbos, Natte sprang and Bierlap (see Suppl. material 2 for pictures of pitfalls and descriptions of sub-areas), stretching along a gradient from the fore-dune complex 400 metres from the sea to shrub and poplar-dominated old dune valleys 2,250 metres inland (see Fig. 1 and Table 1). A total of 100 pitfalls were placed in different vegetation types; (1) bare sand with low vegetation of lichens and/or mosses, (2) grassy plains with Ammophila, Corynephorus, Festuca and/or Calamagrostis dominated vegetations, (3) low shrubs such as Hippophae rhamnoides, Ligustrum or Salix repens and (4) woodland consisting of stands of Alnus, Betula, Populus and/or Quercus. A total of 33 groups were placed with three pitfalls per group (Pitfall 100 was placed near a group of three others), within the four sub-areas. Sampling sites in the four sub-areas were chosen in similar vegetation types at different distances from the sea, for instance, bare sand or woody vegetations.

Table 1.

List of the taxonomic coverage of the species in the dataset (based on current GBIF backbone, spring 2022).

Kingdom

Phylum

Class

Order

Family

# genera

# species

Animalia

Arthropoda

Insecta

Coleoptera

Apionidae

1

7

Animalia

Arthropoda

Insecta

Coleoptera

Brachyceridae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Byrrhidae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Cantharidae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Carabidae

26

79

Animalia

Arthropoda

Insecta

Coleoptera

Chrysomelidae

2

2

Animalia

Arthropoda

Insecta

Coleoptera

Colydiidae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Curculionidae

18

31

Animalia

Arthropoda

Insecta

Coleoptera

Dryophthoridae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Elateridae

8

11

Animalia

Arthropoda

Insecta

Coleoptera

Geotrupidae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Histeridae

1

3

Animalia

Arthropoda

Insecta

Coleoptera

Leiodidae

4

11

Animalia

Arthropoda

Insecta

Coleoptera

Melolonthidae

2

2

Animalia

Arthropoda

Insecta

Coleoptera

Rutelidae

1

1

Animalia

Arthropoda

Insecta

Coleoptera

Silphidae

2

5

Animalia

Arthropoda

Insecta

Coleoptera

Staphylinidae

35

101

Animalia

Arthropoda

Insecta

Coleoptera

Tenebrionidae

6

6

Animalia

Arthropoda

Insecta

Coleoptera

Zopheridae

1

1

Sampling took place using square metal (galvanised iron) containers measuring 24 cm wide, 24 cm long and 27 cm deep. Pitfalls were dug into the ground, their top flush with the soil surface. A small hole, covered with mesh provided drainage of rain water. After the first year of sampling, protective covers were placed over the pitfalls to avoid rain, sand and debris building up inside the traps. These were made from opaque metal sheets placed a few centimetres above the trap using pins in the sand. No killing preservatives were used.

Captures were collected several times a week and aggregated into 7-day interval samples, with some exceptions where the pitfalls were aggregated either after six or eight days; for details, see the data as published on GBIF. All animals caught were identified up to species level and counted. For a sub-selection of species, sex was established. Specimens were stored in glass tubes filled with ethanol (70%). In total, 36,400 samples (100 pitfalls, 52 sampling events per year and 7 years) were collected and recorded.

Species were identified and recorded by staff from the Department of Animal Ecology of Leiden University, as well as from the Natural History Museum in Leiden, assisted by students and a number of voluntary amateur entomologists (Bouman and van Hinsberg 1991a, Bouman and van Hinsberg 1991b). Amongst them, J.T. Wiebes, W.C. Boelens, K. Bakker, A. Spoek-Haanappel, Th. van Egmond, R.E. Kooi and P.J. den Boer are mentioned by name in the metadata.

Quality control: 

Taxonomic nomenclature was updated following the GBIF backbone as well as Nederlands Soortenregister (see Suppl. material 1). These are both dynamic, so this was the current state at the time of checking (spring 2022). Name lists were checked by experts from Naturalis Biodiversity Center and EIS-Kenniscentrum insecten. It should be noted, however, that species have not been re-identified using modern identification keys.

Geographic coordinates were available in the metadata as "Amersfoort coordinates". Although the metadata do not specifically mention how these coordinates were established, we presume that the water company and Leiden University had the necessary skills to measure them with high accuracy. Coordinates were plotted using GIS and transformed into decimal coordinates.

Step description: 

Data were manually recorded from species' paper files into excel files. Excel files were set up with pitfalls in columns and three rows per sample date: male, female or unknown. After transferring data from a species, we checked entries in the excel files using row and column totals available in the paper files. Differences were then traced to their individual cells and adjusted when necessary. After finishing all files, we looked over all files once more thereby checking row and column totals. After digitisation, R scripts were built to transfer CSV data files into GBIF-compatible format (R scripts are available upon request). Finally, the data were published on GBIF by Hemerik and Creuwels (2022) at https://www.gbif.org/dataset/9d02b439-aa5c-4c22-b1d9-d27fbde9e3ee .

Geographic coverage

Description: 

Pitfalls were placed inside an area stretching 1,000 metres from west to east and 1,500 metres from north to south.

Coordinates: 

52.14018N and 52.1557N Latitude; 4.34517E and 4.36339E Longitude.

Taxonomic coverage

Description: 

Taxonomic coverage of the dataset consists of all captures belonging to the order Coleoptera. In total, 267 species were recorded belonging to 110 genera from 18 families. See Table 1 for a list of families and genera caught. See also the table in Suppl. material 1 for a list of all species caught.

As with all historic data, nomenclaturial developments have given rise to alterations in species names. After comparing the historical Dutch Coleoptera catalogue (Brakman 1966) with the most recent edition (Vorst 2010), the following species must be considered.

- Cantharis obscura can refer to both C. obscura L. 1758 and Cantharis paradoxa Hicker, 1960

- Amara aulica might refer to both A. aulica (Panzer, 1796) and Amara gebleri Dejean, 1831

- Calathus mollis can mean C. mollis (Marsham, 1802) and Calathus cinctus Motschulsky, 1850

- Pterostichus nigrita can refer to both P. nigrita (Paykull, 1790) and Pterostichus rhaeticus Heer, 1837

- Phyllobius pyri might refer to both P. pyri (L., 1758) and Phyllobius vespertinus (F., 1793)

- Conosoma testaceus can mean Sepedophilus testaceus (F, 1793) and Sepedophilus marshami (Stephens, 1832)

- Cryptobium fractocorne can refer to both Ochthephilum fracticorne (Paykull, 1800) and Ochthephilum collare (Reitter, 1884)

- Tachyporus chrysomelinus might refer to both Tachyporus chrysomelinus (L., 1758) and Tachyporus dispar (Paykull, 1789)

In addition, the following historic identifications might be wrongly interpreted and should be considered for adjustment in case these data are used:

- Tychius flavicollis Stephens, 1831 is now considered a synonym of Tychius junceus (Reich, 1797), but this name was long misused for the species currently known as Tychius squamulatus Gyllenhal, 1835. The latter is hence the correct name for Tychius flavicollis.

- Heterothops niger is now considered a junior synonym of Heterothops praevius Erichson, 1839 (and is treated as such on GBIF).

- Ilyobates nigricollis might, as well, refer to Ilyobates bennetti Donisthorpe, 1914 for which the name Ilyobates nigricollis was long misused.

- Oxypoda lividipennis should refer to Oxypoda acuminata (Stephens, 1832), not Nehemitropia lividipennis (Mannerheim, 1830). Mannerheim’s name O. lividipennis has long been misapplied to Oxypoda acuminata.

- The entries Sciodrepa umbrina and Dreposcia umbrina probably refer to the same specimen, but we cannot be sure.

Moreover, some identifications are interpreted as species not known to occur in the Netherlands: Dreposcia umbrina (Erichson, 1837), Stenus sylvester Erichson, 1839 and Quedionuchus plagiatus (Mannerheim, 1843)

Taxa included:
Rank Scientific Name Common Name
species Coleoptera
kingdom Animalia Animals
subkingdom Bilateria
phylum Arthropoda Arthropods
subphylum Hexapoda
class Insecta Insects
order Coleoptera Beetles
family Apionidae
family Brachyceridae
family Byrrhidae
family Cantharidae
family Carabidae
family Chrysomelidae
family Curculionidae
family Dryophtoridae
family Elateridae
family Geotrupidae
family Histeridae
family Leiodidae
family Melolonthidae
family Rutelidae
family Silphidae
family Staphylinidae
family Tenebrionidae
family Zopheridae
species Ceratapion carduorum
species Melanapion minimum
species Holotrichapion ononis
species Ceratapion onopordi
species Oxystoma pomonae
species Apion rubens
species Apion rubiginosum
species Notaris acridulus
species Morychus aeneus
species Cantharis obscura
species Acupalpus meridianus
species Agonum marginatum
species Agonum muelleri
species Amara aenea
species Amara apricaria
species Amara aulica
species Amara bifrons
species Amara brunnea
species Amara communis
species Amara convexior
species Amara curta
species Amara eurynota
species Amara famelica
species Amara familiaris
species Amara lucida
species Amara lunicollis
species Amara ovata
species Amara spreta
species Badister bullatus
species Badister lacertosus
species Bembidion assimile
species Bembidion guttula
species Bembidion lampros
species Bembidion obtusum
species Bradycellus caucasicus
species Bradycellus harpalinus
species Broscus cephalotes
species Calathus ambiguus
species Calathus erratus
species Calathus fuscipes
species Calathus melanocephalus
species Calathus mollis
species Cicindela hybrida
species Demetrias monostigma
species Dicheirotrichus placidus
species Dromius angustus
species Paradromius linearis
species Philorhizus melanocephalus
species Dromius quadrimaculatus
species Calodromius spilotus
species Dyschirius tharacicus
species Elaphrus riparius
species Harpalus anxius
species Harpalus melancholicus
species Harpalus rufipes
species Harpalus serripes
species Harpalus servus
species Harpalus smaragdinus
species Harpalus tardus
species Harpalus pumilus
subspecies Harpalus xanthopus winkleri
species Leistus ferrugineus
species Leistus rufomarginatus
species Masoreus wetterhallii
species Syntomus foveatus
species Syntomus truncatellus
species Nebria brevicollis
species Notiophilus aquaticus
species Notiophilus biguttatus
species Notiophilus germinyi
species Notiophilus palustris
species Notiophilus rufipes
species Notiophilus substriatus
species Ophonus cordatus
species Ophonus rufibarbis
species Ophonus rupicola
species Panagaeus bipustulatus
species Agonum sexpunctatum
species Agonum viduum
species Pterostichus diligens
species Pterostichus melanarius
species Pterostichus minor
species Pterostichus niger
species Pterostichus nigrita
species Pterostichus oblongopunctatus
species Pterostichus strenuus
species Poecilus versicolor
species Synuchus vivalis
species Trechus quadristriatus
species Galeruca tanaceti
species Sermylassa halensis
species Anthonomus rubi
species Mogulones crucifer
species Ceutorhynchus hirtulus
species Nedyus quadrimaculatus
species Cleonis pigra
species Cossonus linearis
species Dorytomus dejeani
species Dorytomus hirtipennis
species Dorytomus longimanus
species Dorytomus tortrix
species Dorytomus ictor
species Rhinusa collina
species Rhinusa linariae
species Brachypera dauci
species Hypera nigrirostris
species Hypera plantaginis
species Hypera postica
species Limobius borealis
species Limobius mixtus
species Orchestes fagi
species Orthochaetes setiger
species Otiorhynchus ovatus
species Philopedon plagiatum
species Phyllobius argentatus
species Phyllobius pyri
species Polydrusus cervinus
species Charagmus griseus
species Strophosoma melanogrammum
species Strophosoma capitatum
species Tychius flavicollis
species Tychius quinquepunctatus
species Sitophilus granarius
species Ectinus aterrimus
species Agriotes lineatus
species Agriotes obscurus
species Agrypnus murinus
species Cardiophorus asellus
species Dalopius marginatus
species Cidnopus aeruginosus
species Melanotus punctolineatus
species Melanotus villosus
species Prosternon tessellatum
species Selatosomus aeneus
species Trypocopris vernalis
species Saprinus aeneus
species Saprinus immundus
species Saprinus semistriatus
species Catops chrysomeloides
species Catops coracinus
species Catops morio
species Catops nigricans
species Catops tristis
species Choleva jeanneli
species Choleva oblonga
species Choleva paskoviensis
species Dreposcia umbrina
species Sciodrepoides fumatus
species Sciodrepoides watsoni
species Polyphylla fullo
species Serica brunnea
species Phyllopertha horticola
species Nicrophorus humator
species Nicrophorus investigator
species Nicrophorus vespilloides
species Thanatophilus rugosus
species Oiceoptoma thoracicum
species Acidota cruentata
species Aleochara curtula
species Aleochara ruficornis
species Aleochara sparsa
species Amischa analis
species Drusilla canaliculata
species Dinaraea aequata
species Dinaraea angustula
species Acrotona aterrima
species Atheta crassicornis
species Atheta euryptera
species Mocyta fungi
species Atheta gagatina
species Atheta harwoodi
species Liogluta microptera
species Mocyta orphana
species Atheta sodalis
species Bledius pygmeus
species Lordithon thoracicus
species Bolitobius castaneus
species Sepedophilus immaculatus
species Sepedophilus pedicularius
species Sepedophilus testaceus
species Creophilus maxillosus
species Ochthephilum fracticorne
species Falagrioma thoracica
species Gyrohypnus angustatus
species Gyrohypnus atratus
species Gyrohypnus punctulatus
species Heterothops dissimilis
species Heterothops niger
species Heterothops quadripunctulus
species Ilyobates nigricollis
species Anthobium atrocephalum
species Anthobium unicolor
species Lathrobium fulvipenne
species Lathrobium geminum
species Lobrathium multipunctum
species Sunius melanocephalus
species Mycetoporus baudueri
species Mycetoporus lepidus
species Mycetoporus clavicornis
species Mycetoporus forticornis
species Mycetoporus punctus
species Ischnosoma splendidum
species Zyras collaris
species Zyras funestus
species Zyras laticollis
species Zyras limbatus
species Pella lugens
species Ocalea badia
species Ocypus aeneocephalus
species Tasgius ater
species Ocypus brunnipes
species Tasgius morcitans
species Ocypus picipennis
species Omalium caesum
species Omalium italicum
species Omalium rivulare
species Othius subuliformis
species Othius punctulatus
species Ousipalia caesula
species Oxypoda brachyptera
species Oxypoda exoleta
species Oxypoda induta
species Nehemitropia lividipennis
species Oxypoda opaca
species Oxypoda procerula
species Oxypoda spectabilis
species Oxypoda togata
species Oxypoda vittata
species Oxytelus laqueatus
species Anotylus rugosus
species Paederidus ruficollis
species Metopsia clypeata
species Quedius persimilis
species Quedius boops
species Quedius curtipennis
species Quedius fuliginosus
species Quedius lateralis
species Quedius longicornis
species Quedius molochinus
species Quedius nigrocaeruleus
species Quedius nitipennis
species Quedius picipes
species Quedionuchus plagiatus
species Quedius semiaeneus
species Quedius semiobscurus
species Geostiba circellaris
species Stenus clavicornis
species Stenus geniculatus
species Stenus impressus
species Stenus sylvester
species Rugilus rufipes
species Tachinus corticinus
species Tachinus marginellus
species Tachyporus atriceps
species Tachyporus chrysomelinus
species Tachyporus hypnorum
species Tachyporus pusillus
species Tachyporus scitulus
species Tachyporus tersus
species Xantholinus laevigatus
species Xantholinus linearis
species Xantholinus longiventris
species Xantholinus elegans
species Xantholinus tricolor
species Crypticus quisquilius
species Isomira murina
species Melanimon tibialis
species Cylindrinotus pallidus
species Phylan gibbus
species Opatrum sabulosum
species Orthocerus clavicornis

Temporal coverage

Notes: 

The pitfalls collected specimens from 1 March 1953 through to 16 March 1960. Pitfalls 61 – 100 were placed on 1 March 1953. Pitfalls 1 – 60 on the 4th of March. The 30 pitfalls with numbers > 100 (see below) were placed on 9 April 1959.

Usage licence

Usage licence: 
Creative Commons Public Domain Waiver (CC-Zero)

Data resources

Data package title: 
Meijendel research 1953-1960
Number of data sets: 
1
Data set name: 
Meijendel research 1953-1960
Data format: 
csv
Description: 

The dataset contains occurrence data from 100 pitfalls that were collected weekly from March 1953 – March 1960. The dataset contains 267 beetle species together with a number of mammal species. A description of column headers used is given below.

Column label Column description
basisOfRecord state of the recorded specimen.
class class name.
coordinateUncertaintyInMetres The horizontal uncertainty distance (in metres) from the given decimalLatitude and decimalLongitude.
country The name of the country in which the Location occurs.
countryCode The standard code for the country in which the Location occurs.
decimalLatitude The geographic latitude (in decimal degrees, using the spatial reference system given in geodeticDatum) of the geographic centre of a Location.
decimalLongitude The geographic longitude (in decimal degrees, using the spatial reference system given in geodeticDatum) of the geographic centre of a Location.
eventDate date of registration of event.
eventID Unique identifier for each event per date, per pitfall.
eventRemarks additional information on event status.
eventTime dates in between which the event is created.
family family name.
lifestage lifestage at which specimen was caught.
geodeticDatum The coordinate system and set of reference points upon which the geographic coordinates are based.
individualCount number of recorded specimens per occurrenceID.
kingdom kingdom name.
locality The specific name of the place of occurrence.
locationID unique code for each sampling location.
occurrenceID Unique identifier for each occurrence per species, per date, per pitfall.
occurrenceRemarks additional information on occurrence status.
occurrenceStatus present.
order order name.
original_identified_as originally identified as species.
ownerInstitutionCode the institution having custody of the object.
phylum phylum name.
recordedBy institution by which specimen is identified and recorded.
samplingEffort manner in which sampling is performed.
samplingProtocol type of sampling technique used.
sampleSizeUnit unit in which samples are assembled.
sampleSizeValue number of sample units (days) of the eventID.
short.scientific.name Eightletter abbreviation of Genus and species name of original scientific name.
startDayOfYear day of the year from start of year.
scientificName current scientific name.
taxonRank taxonomic level to which specimen is identified.
type sex.
verbatimLatitude latitude as originally recorded.
verbatimLongitude longitude as originally recorded.
verbatimSRS The original coordinate system and set of reference points upon which the verbatim latitude and longitude are based.

Additional information

As with all datasets, there are a number of details, peculiarities and shortcomings in the data that should be taken into account when working with the dataset:

Pitfalls 7-18 were moved to a new location in 1955. This was because the infiltration of river water into the dunes created lakes and these pitfalls would be flooded if not moved. On 20 June 1955, pitfalls 7-12 were moved 8 metres to the north. On 19 August 1955, pitfalls 13, 14 and 15 were moved 50 metres northwest on to the newly-formed peninsula inside the newly-formed infiltration lake. Lastly, pitfalls 16, 17 and 18 were placed on the eastern side of the same peninsula on the same date.

In 1959, an additional 30 pitfalls were placed close to their respective counterparts (number of pitfall +100), presumably to check whether the old traps were still reliable. The galvanised iron pitfalls had an increasingly rough surface due to oxidation and it was suspected that certain groups of animals (for instance spiders, see Noordam 1996) were capable of climbing out of the pitfalls. These extra pitfalls have all been added to the dataset.

In 1954, pitfalls were left unchecked for a month. On dates 26 January 1954, 2 and 9 February 1954, pitfalls were, therefore, not emptied. Presumably this was because of wintery conditions.

Some species folders only have records for 1953/1954. It cannot be guaranteed that these species were caught in later years. In other words, the paper files may not have survived. Therefore, absence of recorded captures in these cases do not constitute "hard zeros". Too many species only have record sheets for the first year or two years, to be realistic. Only a few of these species have explicit remarks on data sheets stating which years no captures were present. All other species with records for the first two years only must be treated with suspicion and restraint for subsequent years.

Part of the dataset also consists of around 5,000 records of moles (Talpa europea), mice (identified up to order) and shrews (Sorex spec.) caught with the pitfalls. Since no killing preservatives were used, these mammals will have eaten part of the invertebrates in that pitfall. Therefore, abundance of invertebrate catches must be viewed as minimum abundance. In case small mammals were recorded for the preceding seven day period, absence in that pitfall cannot be said to be absence in the area where the pitfall is situated and, therefore, should be handled like "soft-zeros". To a lesser degree, these soft-zeros are also the case where no mammals were caught, since no preservation killing fluids were used and carnivorous species will have preyed on other species in that pitfall.

The year 1955 saw the first outbreak of Myxomatosis in rabbits in the Netherlands, which decimated their population in Meijendel soon after. Grazing pressure from rabbits in the dune areas before Myxomatosis was high. In fact, ecologists at the time considered pressure from rabbits harmful to the vegetation and ecosystem as a whole. In the years following 1955, the first clear signs of grass and shrub encroachment were recorded. This will have had a significant influence on ground-dwelling beetle populations (see de Bruyn 1997).

Meijendel in the 1950s already had a long history of exploitation as a drinking water extraction area and provided water to the rapidly growing cities of The Hague and Leiden. As a result, Meijendel was becoming increasingly dry, with ground water levels dropping several decimetres in comparison to 19th century levels. Around 1900, the area contained 600 hectares of wet dune valleys. In 1955, vegetation surveys showed only 6 hectares of this species rich habitat remained (Boerboom 1960).

Acknowledgements

This project was made possible with grants from NLBIF (nlbif2020.005) and drinking water company Dunea Duin & Water. We acknowledge the efforts by Leiden University for collecting the data and archiving results in such a way that, decades later, data were still relatively easy to digitise. The authors would like to thank Theodoor Heijerman, Oscar Vorst and Hans Turin for checking nomenclature, whereby Oscar Vorst is acknowledged for additional interpretation of historic species names and Harrie van der Hagen for helping with cross-checking water infiltration data. The authors thank Gerrit-Jan de Bruyn for safekeeping the original paper archive. Lisa Hoekema is thanked for helping with digitising a selection of species. Aart Noordam is acknowledged for scanning the photographs of the pitfall surroundings. Aldo Bouman and Arjen van Hinsberg are thanked for making available their unpublished report. Eddy van der Meijden is thanked for his help in recovering the report by Bouman and van Hinsberg. Wouter Koenders has provided figure 1B using GIS software and Rik Waenink the map at the end of Supplementary 2.

Author contributions

LH conceived preserving and publishing of the dataset. LH and GMG digitised and checked the data. LH wrote the R script. GMG and LH wrote the paper. Both authors agree with the final version of the paper.

References

Supplementary materials

Suppl. material 1: Overview of all beetle species included in the historical database and entered for publication in GBIF (Global Biodiversity Information Facility) 
Authors:  G.M. Gerrits and L. Hemerik
Data type:  pdf file
Suppl. material 2: Description and pictures of the location of the pitfalls  
Authors:  G.M. Gerrits and L. Hemerik
Data type:  pdf file
Brief description: 

Short descriptions of the direct surroundings as well as photographs of the pitfalls used in the Meijendel Research Project between 1953 and 1960

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