# Forest Heterogeneity by Chain Saw: How Between‐Patch Variation in Old Growth Attributes Changes the Metacommunities of Beetles

## TL;DR

This study shows that increasing forest structural diversity boosts beetle biodiversity through specific ecological processes.

## Contribution

A novel statistical framework was developed to detect metacommunity processes in beetle communities under structural heterogeneity.

## Key findings

- Heterogenized forests showed ~60 more beetle species due to increased α-diversity linked to mass-effect.
- β-diversity increased by ~10%, supporting species-sorting as a key process.
- Enhanced structural heterogeneity shifts dominance from patch-dynamics to mass-effect and species-sorting.

## Abstract

Metacommunity theory has expanded our understanding of how spatial dynamics and local interactions influence species communities. Different assembly archetypes, reflecting different roles of species differences, habitat differences, and dispersal have been described, but we lack empirical studies specifically in terrestrial habitats testing which archetype is most important. In a replicated design, we experimentally enhanced structural between‐patch heterogeneity in homogeneous production forests and developed a statistical framework controlling for sample incompleteness to detect different metacommunity processes. Meta‐analyses on > 100 K individuals of > 1.3 K beetle species showed an increase of ~60 species in heterogenized forests at γ‐level promoted by increasing α‐diversity consistent with the mass‐effect and an increase of β‐diversity by ~10% supporting species‐sorting. Additionally, we tested β‐deviations from random assembly as a proxy of neutral processes. Findings indicate that enhancing structural heterogeneity can shift forests from patch‐dynamics dominance towards mass‐effect and species‐sorting, offering a promising pathway to restore biodiversity in managed landscapes.

Metacommunity theory has expanded our understanding of how spatial dynamics and local interactions influence species communities, but we lack empirical studies specifically in terrestrial habitats testing which archetype is most important. In a replicated design we experimentally enhanced structural between‐patch heterogeneity in homogeneous production forests and developed a statistical framework controlling for sample incompleteness to detect different metacommunity processes. Meta‐analyses on > 100 K individuals of > 1.3 K beetle species showed an increase of ~60 species in heterogenized forests at γ‐level promoted by increasing α‐diversity consistent with the mass‐effect and an increase of β‐diversity by ~10% supporting species‐sorting.