Temporal trends of functional, phylogenetic, and species diversity do
not go in par in Austrian butterflies
Abstract
Climate change and anthropogenic alteration of landscapes negatively
impact the abundance and diversity of plant and animal communities
worldwide. Much less is known about the effects on phylogenetic
diversity and community functioning. Here we use long-term observation
data (1980 – 2022) from the Austrian Alps to assess how butterfly
communities adjust community structures and functionality to increasing
temperatures along the elevation gradient and how these changes are
linked to trait expression and community functioning? Diversity
significantly decreased at low and intermediate, and increased at high
altitudes. Functional attribute diversity was significantly lower than
expected by a random model at intermediate and high altitudes and
increased with time at high, but not at intermediate and low altitudes.
Multifunctionality significantly decreased at intermediate and high
altitudes Phylogenetic diversity did not show significant temporal
trends at low altitude, but significantly increased with time at
intermediate and high altitudes. Multifunctionality was not
significantly correlated with FAD, but decreased with increasing
phylogenetic diversity. We conclude that the ongoing homogenisation of
Alpine butterfly communities strongly affect species, functional and
phylogenetic diversity. The directions of these changes heavily depend
on altitude and therefore on specific climatic conditions. Higher
altitudes face decreasing butterfly multifunctionality despite of
increasing species richness due to climate induced altitudinal up-hill
shifts of many species. The assessment of species richness and diversity
alone, as provided by common species surveys, might give a false
impression about the state and functioning of Alpine insect communities
in the course of climate change.