How and when should flightless, saproxylic, litter‐dwelling coleoptera be surveyed?

Abstract

1. The limited dispersal and the high trophic requirements of flightless saproxylic beetles makes them good indicators of spatial and temporal continuity. Few studies have been conducted on these species, and the two main studies produced contradictory results. Knowledge is thus lacking on this fauna, but before performing experiments to assess their value as indicators, it is important to know how and when they can be sampled.2. Sieving litter and Berlese extraction in six oak woodlands showed that sampling 10 trees per forest is sufficient to capture 97.2% of the fauna present.3. Two stands were surveyed at monthly intervals for 2 years to determine the species phenology. All the species were present throughout the year. Variation in abundance was only observed in four out of 11 species. Spring and fall were shown to be the best periods to survey them in the litter. No significant variation in abundance was observed between the two sampling years. This fauna thus appears to be very stable over time.4. Certain climate parameters, high humidity (little sunshine and rainfall several days before sampling) may result in the beetles being more abundant in the litter at certain times. For efficient sampling, long periods of fine weather should thus be avoided.

The influence of spatial and temporal discontinuities of forest habitats on the current presence of flightless saproxylic beetles

“…Beetles were sampled in the 27 forests in February 2014 using the litter sieving method [ 14 , 23 , 36 ]. In each sampled forest, one homogeneous hectare in the center of the forest was selected to constitute the entomological sampling plot.…”

“…One litre of sieved litter was collected per tree, making ten litres per stand. The number of trees sampled and the litter volume are sufficient to collect 97.2% of the FSLB present, even in rich sites [ 14 ]. Arthropods were extracted from the litter using a Berlese extractor [ 14 ].…”

“…The number of trees sampled and the litter volume are sufficient to collect 97.2% of the FSLB present, even in rich sites [ 14 ]. Arthropods were extracted from the litter using a Berlese extractor [ 14 ]. Species were sent to a specialist for identification by morphological analysis.…”

“…FSLB can be found at adult stage in the litter throughout the year. For most of the species, there is no monthly difference in their abundance, other FSLB show variations in their abundance but are always present [ 14 ]. Some of them have lived in their adult stage more than one year in captivity [ 15 ].…”

“…FSLB have been the subject of very few studies [ 21 , 23 – 25 ] and a sampling method dedicated to this group has only recently been published [ 14 ].…”