Assemblage characterization
Species richness and abundance was assessed by the mean number of
species or individuals respectively, per trapping event and site (i.e.,
total number of specimens per species of a particular trap divided by
number of used traps). Thus, abundances were corrected for sampling
biases due to trap failures because of weather or technical problems.
Species presence-absence data were used for the assessment of species
composition and assemblage similarity. Species accumulation curves were
plotted for each trap with the cumulative number of recorded species vs.
number of cumulative trapping events to assess sampling adequacy and
comparability of the results. Inventory completeness in each sampling
locality was measured by the number of observed species in respect to
the number of species predicted by the Chao1 richness estimator, i.e.,
the total number of species in each locality with lower and upper limits
(Chao and Lee 1992; Zou and Axmacher 2021). Sampling data (i.e.,
specimens per trap) were pooled for each trap from all four sampling
campaigns (2019 I, 2019 II, 2020 I, 2020 II) for total assemblage
analyses. A two-way cluster analysis (species vs locality) was performed
based on presence-absence data using the Jaccard similarity index
(Jaccard, 1912) in PAST v. 3.25 (Hammer et al. 2001).
The alpha diversity was measured using Shannon index, Simpson index and
Evenness for each locality (Shannon 1948; Simpson 1949; Hill 1973) being
calculated in PAST v. 3.25. Approximate confidence intervals for all
these indices were computed with a bootstrap procedure (number of random
samples (default 9999) with 95 % confidence interval).