Data from: Fine-scale vertical stratification and guild composition of saproxylic beetles in lowland and montane forests: similar patterns despite low faunal overlap

The finer scale patterns of arthropod vertical stratification in forests
are rarely studied and poorly understood. Further, there are no studies
investigating whether and how altitude affects arthropod vertical
stratification in temperate forests. We therefore investigated the
fine-scale vertical stratification of diversity and guild structure of
saproxylic beetles in temperate lowland and montane forests and compared
the resulting patterns between the two habitats. The beetles were sampled
with flight intercept traps arranged into vertical transects (sampling
heights 0.4, 1.2, 7, 14, and 21 m). A triplet of such transects was
installed in each of the five sites in the lowland and in the mountains;
75 traps were used in each forest type 381 species were collected in the
lowlands and 236 species in the mountains. Only 105 species (21%) were
found at both habitats; in the montane forest as well as in the lowlands,
the species richness peaked at 1.2 m, and the change in assemblage
composition was most rapid near the ground. The assemblages clearly
differed between the understorey (0.4 m, 1.2 m) and the canopy (7 m, 14 m,
21 m) and between the two sampling heights within the understorey, but
less within the canopy. The stratification was better pronounced in the
lowland, where canopy assemblages were richer than those near the forest
floor (0.4 m). In the mountains the samples from 14 and 21 m were more
species poor than those from the lower heights. The guild structure was
similar in both habitats. The main patterns of vertical stratification and
guild composition were strikingly similar between the montane and the
lowland forest despite the low overlap of their faunas. The assemblages of
saproxylic beetles were most stratified near ground. The comparisons of
species richness between canopy and understorey may thus give contrasting
results depending on the exact sampling height in the understorey.