Weed flora monitoring data from agricultural fields under conventional use in the AgroScapeLabs Quillow in Northeast Germany from 2000 to 2022 – here: plot vegetation surveys

Systematic vegetation surveys were performed from 2000 to 2022 yearly within the “Quillow-AgroScapeLab”, located in the north-eastern part of the German lowlands (Figure 1). The area is 290 km2, the altitude ranges between 0–100 m above sea level. The landscape is of glacial origin and is characterised by a heterogeneous distribution of the following soil types: luvisols, arenosols, phaeozem, retisols, histosols, and planosols. The monitroing was varied out on in total 43 single agricultural fields, 23 out of them belong to the basic monitoring program at AgroScapeLabs Quillow (performed by ZALF) where other parameters have been monitored over time and 20 fields belonging to the Additional program, where only the weed monitoring has been performed. The fields of the Basic program have been selected based on a soil representativeness analysis based on soil map analyses in order to cover the most common and specific soil types within the whole Quillow (river) catchment. The additional program were set up in order to reach a better spatial cover over the whole catchment and to increase the field number. For each field a soil profile description is available from ZALF data repository. Management data are only available from 2000-2006. From later years at least the crop type is available. At each field there were three fixed points installed and identified with GPS data (figure 2). Surveys were repeated every year at exact the same GPS coordinates. Not every field could be monitored every year due to some restrictions by the field owners. From 2019 on winter rape fields were not be monitored anymore due to monitoring overlap with plant protection measures. Vegetation surveys were carried out on fixed survey quadrats of 25m²size, marked with boundary ropes. Survey included the estimation of the crop stands structure including data on over all vegetation coverage, crop coverage and height as well as total weed coverage. In a second step weed species inventory was identified by using taxonomic literature (Rothmaler et al. various editions) and coverage of each single species was determined using a modified rating scale according to BRAUN-Blanquet (1964) and already specified to concrete percentage values out in the field. Plants that could not be clearly identified were sampled and re-identified in the laboratory. By adding the data into a databank, species names have to be corrected to the nomenclature of Wisskirchen and Häupler 1998. Vegetation surveys have been carried out after herbicide treatments (if there were any) mostly between end of april, may, and june. (see data tables!). The number of survey dates per years was 1-2. It varies over the years and crops. Please note: a separate dataset is available from the same study area and from the same fields (https://doi.org/10.4228/zalf-c2rn-7f27), which contains information on the species occurrence of weeds on the arable land using a different method (mapping) from a different survey area size (0.5-1ha).