A box quadrat for standardised sampling of Orthoptera in open habitats: Design, handling, applications and baseline data

Abstract

Globally, insects are declining at an alarming rate. Therefore, there is an urgent need for standardised monitoring methods to detect changes in insect populations at an early stage. Box quadrat sampling enables highly precise assessments of Orthoptera community composition within a specific area. However, a detailed design of a box quadrat that guarantees an easy workflow, precise descriptions of its handling and a compilation of baseline data for future comparisons have yet been lacking. Based on thirty years of our own experience in box quadrat sampling, we present here: (i) the detailed design of a box quadrat, (ii) its standardised handling in the field (including a video as a supplement), (iii) its applications and (iv) Orthoptera species richness and abundance baseline data for open habitats. The low construction costs (∼300 €) and simple design allow for a wide distribution of this type of box quadrat in future. Moreover, due to the plug system and the light aluminium construction, the quadrat can easily be transported, assembled, handled and dismantled by one person. For comparisons of Orthoptera species richness, abundance and community composition between habitats, we recommend using a quadrat of 2 m² size and 0.8 m height and a minimum sampling area of 20 m² per plot (10 touchdowns per plot). For long-term monitoring or when species are sampled that generally occur in low density, a sampling area of 30 m² (15 replicates) is suggested. By contrast, for the surveys of tiny species (e.g., groundhoppers) and developmental stages (nymphs), smaller box quadrats can also be used and the sampled area per plot can be below 20 m². Box quadrat sampling is less dependent on favourable weather conditions and vegetation structure than many other insect survey techniques. Overall, it allows rapid and highly precise assessments of Orthoptera community composition.