DOI: 10.5061/dryad.31zcrjdq1
title: Dataset: Arthropod overwintering in bioenergy crops

description: Perennial energy crops (PECs) can reduce negative impacts of intensive
 silage maize cultivation on the environment. Further, remaining vegetation
 of PECs after harvest may provide suitable habitat and more beneficial
 overwintering conditions for arthropods than maize. We hypothesized that
 after harvest and in winter, arthropod abundance and biomass are higher in
 PECs than in silage maize. In a field experiment, we compared the two PECs
 cup plant and field grass with silage maize regarding their suitability as
 autumn (post-harvest) and overwintering habitats for arthropods. We
 measured soil temperature and moisture and analyzed biomass as well as
 abundance of autumn-active and overwintering arthropods of these three
 crops. During autumn we assessed arthropods by suction sampling in 24
 plots of the experimental field. In spring we assessed soil-emerging
 arthropods for four times in 18 plots. In PEC plots, soils were moister
 and less exposed to cold temperatures than in maize. Compared to maize,
 total arthropod abundance and biomass were higher in PEC plots for both
 sampling periods. Results were similar for most examined arthropod taxa.
 Our results demonstrate that, compared to silage maize, the PECs provide
 suitable post-harvest habitats and constitute more suitable overwintering
 habitats for arthropods. We assume that differences are based on lack of
 disturbance and the provision of vegetation structures after harvest that
 function as overwintering habitat for arthropods. We conclude that
 positive effects of PECs on ground arthropods are not limited to their
 growing time but continue after harvest and during winter.
description: Maize, cup plant and field grass were grown on an experimental
 field in Braunschweig, Germany. Details for crop management can be found
 in Grunwald et al. 2020 GCB Bioenergy. The habitat suitability of the
 three crops for arthropods was assessed with two methods. Arthropods were
 collected with suction sampling after harvest and emerging arthropods were
 assessed using ground photo-eclectors in spring. Further, soil temperature
 and moisture were assessed in spring and winter.
 Temperature was measured with Data loggers ‘Tinytag Plus
 2-TGP-4500’ (Gemini Data Loggers, Chichester, UK) (range: –25 °C to +85 °C
 and an accuracy of 0.01 °C). Data loggers were placed in waterproof
 plastic boxes for protection, positioned 15 cm below soil level and
 covered with soil. Moisture was measured with the
 device ‘HD2’ and the probe ‘TRIME-PICO 64’ (IM-KO Micromodultechnik GmbH,
 Ettlingen, Germany) relative soil moisture was measured at three points
 around the emergence trap set of each plot on every first and last day of
 emergence sampling in 2019. The device measures volumetric water content
 of soils based on conductivity and is suited for different types of soil
 and works efficiently at a temperature range from –15 °C to +70
 °C. For descriptive analysis and plotting winter
 moisture was summarized to subplot level. The respective two measurements
 of soil moisture in winter per plot were averaged and used as a response
 variable in models. For measurements in spring mean temperatures per day
 and subplot were calculated and moisture data was averaged across sampling
 positions and subplot. <br><br>A suction sampling device
 (‘ecoVac’, ecoTech GmbH, Bonn, Germany) was used on 2016-09-26 in all 24
 plots (eight replicates per crop) between 10:30 and 16:30. Per plot, 18
 consecutive sampling points with a distance of 2 m along a central line,
 were assessed, starting 2 m in from the edges of the plots (sum:  0.28
 m<sup>2</sup> per plot). Diameter: 14 cm, suction strength: 14
 m s<sup>-1</sup>, duration: 20 seconds.
 Ground photo-eclectors (‘Modell 250’ by ecoTech GmbH Bonn,
 Germany) were used in 18 plots. They had a height of 95 cm and consisted
 of a plastic cylinder with a cone-shaped tent-structure on top of it. The
 cylinder was dug partly into the ground, encircling an area of 0.25
 m<sup>2</sup>. Let-in flush with the inner wall of the
 cylinder was one pitfall trap (plastic cups with a volume of 0.5 l and a
 diameter of 9.5 cm) dug into the ground. Pitfall traps were partly filled
 with monoethylene glycol (MEG).Transparent eclector head boxes attached to
 the top of the tents were also filled with MEG and conserved arthropods
 moving toward light at the top of the tent. One emergence trap set was
 placed on the longitudinal side of each plot, one meter from the
 edge. From suction samples and ground photo-eclectors
 all arthropods (per plot) were poured onto a sieve of 0.5 mm mesh width
 and rinsed with tap water. The sieve was placed over a vessel until the
 time between two drops reached more than 20 seconds after which the sample
 was weighted (‘Sartorius handy h51’ by Sartorius AG, Göttingen, Germany;
 accuracy ± 0.3 mg). Afterwards, arthropods were sorted
 into coarse taxonomic groups (Araneae, Opiliones, Isopoda, Chilopoda,
 Diplopoda, Diptera, Hymenoptera, Carabidae, Staphylinidae, other
 Coleoptera, Hemiptera, Dermaptera and ‘others’). For both methods data on
 abundance was analyzed separately for individual taxa and for all taxa
 combined.