Transfer of invertebrates with hay during restoration operations of extensively managed grasslands in Switzerland.

Introduction: Hay transfer from a speciose donor meadow to a species-poor receiver grassland is an established method to restore species-rich grassland plant communities. However, it has rarely been investigated to which extent invertebrates can be transferred with hay during such operations, which was the aim of this study.

Methods: Sampling was conducted in eight sites of the Swiss lowlands with one donor meadow and two receiver sites each. On the receiver sites, three to four white bed sheets of one square meter each were deployed on the ground to receive a standard quantity of fresh hay just transferred from the donor meadow. All living invertebrates were collected from these sheets with an aspirator and subsequently identified to order level.

Results: On average (± SD), 9.2 ± 11.3 living invertebrates per square meter were transferred with the hay. Beetles were the most abundant species group, representing 46.9% of all transferred invertebrates, followed by true bugs (8.9%) and spiders (7.0%). More individuals were transferred when the donor meadow was mown with a hand motor bar mower than with a rotary disc mower. Similarly, more invertebrates were transferred when the hay was transported loosely with a forage wagon than compacted as bales.

Discussion: While this study demonstrates that living invertebrates can be transferred with the hay, their subsequent survival and establishment remains to be explored.

Implications For Insect Conservation: We recommend using a hand motor bar mower and a forage wagon for increasing the survival probability of invertebrates in hay transfer.