Data for: A National-scale Dataset of Arable Plant Abundance from Citizen Science Surveys of Swedish Field Margins

Plants growing in Swedish field margins.

The survey was done as a collaboration between the Swedish Botanical Society and the Swedish University of Agricultural Sciences SLU. Volunteer botanists could survey fields of their own choosing or from a "priority" grid. The grid was created to unsure an even spread across Sweden and reduce the risk of bias. All field types were of interest, except for pasture and permanent grassland. Surveyors measured out a 100*1 m transect at the edge of the ploughed part of the field edge, and all plants within this transect were noted and counted. Additionally, surveyors took note of soil type, growing crop, management type, and the number of field corners and entrances along the transect. The surveyor could also give comments to the site, if they observed soemthing of interest (e.g herbicide damage). Findings were reported through the project "Åkerogräsinventeringen" on the Swedish Species Information Centre.

Choice of fields: There were two ways for surveyors to choose a field. They could either choose one themselves, or they could pick one from a priority grid that was evenly spread across Sweden (where there is arable land). All field types were of interest, with the exception of pastures and permanent grassland. Choice of individuals: In the field, all plants that were rooted in the measured transect were noted. They were counted or estimated for abundance when counting was not possible. The surveyor was encouraged to identify the species to as much detail as they could, but sections, species complex and determination to genus were also accepted. Data cleaning: During cleaning, faulty coordinates and registrations were corrected in communication with the surveyor of that field, and/or by comparing to existing databases. In the cases where uncertainties remained, we elected to remove the site from the cleaned version of the dataset. This includes cases where: * It was not possible to say with certainty which field had been surveyed. * Plants had not been counted and only noted. * The field was surveyed after harvest. In some cases, single entries were removed from the cleaned and filtered dataset. This includes: * Woody plants. * If it was likely the plant had been sown (e.g. Phleum pratense in a field where grass seeds had been sown).

Inventeringsdata samlades in av volontärer från Svenska botaniska föreningen. Inventerare kunde välja fritt vilka fält de skulle inventera, men uppmuntrades att välja fält slumpartat (exempelvis genom att välja fält från en karta). De kunde även välja fält från ett rutnät av prioriterade områden, i syfte att ge bättre täckning och statistisk reproducerbarhet. I fält mättes en sträcka på 100 meter upp längs kanten av den plöjda delen av åkern, och 1 meter in (i riktning mot åkerns mitt), och koordinater för sträckans mitt skrevs ner. Samtliga växter som fanns inom denna transekt noterades och deras antal uppskattades. Även relevanta fältparametrar (jordmån, odlad gröda, odlingsform) noterades. Inventeraren kunde också ge övriga kommentarer på fältet, exempelvis om det var insått med något, hade besprutats, eller övrigt som kunde anses vara av värde. All inventeringsdata rapporterades in till projektet "Åkerogräsinventering" på Artdatabanken.