Data from: LiDAR-derived canopy structure supports the more-individuals hypothesis for arthropod diversity in temperate forests

Despite considerable progress in the ability to measure the complex 3-D
structure of forests with the improvement of remote-sensing techniques,
our mechanistic understanding of how biodiversity is linked to canopy
structure is still limited. Here we tested whether the increase in
arthropod abundance and richness in beech forest canopies with increasing
canopy complexity supports the more-individuals hypothesis or the
habitat-heterogeneity hypothesis. We used fogging to collect arthropod
samples from 80 standardized plots from canopies of single- to
multi-layered mature montane European beech stands. Tree height and an
independent measure of vertical heterogeneity — the vertical distribution
ratio — on each arthropod sampling plot were derived from high-resolution
full-waveform airborne laser scanning data. Mixed-model path analysis
based on almost 20,000 specimens of 762 species from 11 orders provided
support for the more-individuals hypothesis, with higher arthropod
abundance but not higher species richness in stands with a more equal
vertical distribution of plant biomass. By contrast, we found no support
for the habitat-heterogeneity hypothesis. The increase in the number of
individuals with increasing vertical distribution of biomass might be
caused either by increasing leaf area, as indicated by higher space
filling and productivity in multi-layered stands, or by higher persistence
of arthropod populations owing to better shelter, reduced competition and
more refuges under harsh conditions, or by both. High-resolution airborne
laser scanning, with its ability to penetrate dense canopies under leaf-on
conditions, has proved suitable for measuring vertical structures as a
predictor for canopy diversity. Expanding combinations of remote-sensing
and canopy-biodiversity data opens many avenues for improving our
understanding of the link between diversity and forest structures.