Data from: Effects of climate and forest development on habitat specialization and biodiversity in Central European mountain forests

Mountain forests are biodiversity hotspots with competing hypotheses
proposed to explain elevational trends in species richness. The
altitudinal-niche-breadth-hypothesis suggests decreasing specialization
with elevation, which could lead to decreasing species richness and weaker
differences in species richness and beta diversity among habitat types
with increasing elevation. Testing these predictions for bacteria, fungi,
plants, arthropods, and vertebrates, we found decreasing habitat
specialization (represented by forest developmental stages) with elevation
in mountain forests of the Northern Alps – supporting the
altitudinal-niche-breadth-hypothesis. Species richness decreased with
elevation only for arthropods, whereas changes in beta diversity varied
among taxa. Along the forest developmental gradient, species richness
mainly followed a U-shaped pattern which remained stable along elevation.
This highlights the importance of early and late developmental stages for
biodiversity and indicates that climate change may alter community
composition not only through distributional shifts along elevation but
also across forest developmental stages.