Forest Gaps and Habitat Specialists: The Impact of Canopy Openings and Deadwood Management on Insect Communities

• Applicant: Dr. Mareike Kortmann
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568934442

Increasing tree mortality and forest management practices are reducing forest canopy cover across Europe, potentially leading to the decline of forest specialists and a loss of ecosystem stability. Insects are an ideal study group for assessing the impacts of forest dieback and deadwood accumulation or removal, as they are highly responsive to both canopy cover and deadwood availability. However, two main challenges arise: first, disentangling the effects of canopy openings and deadwood accumulation, which naturally occur together in disturbance events but are typically separated by management practices that remove deadwood; second, overcoming the taxonomic limitations of most studies, as habitat preferences remain unknown for the majority of insect species. This study aims to develop a comprehensive catalogue of forest affinities for insect metabarcoding data, covering a wide range of taxa. The first step is to classify forest affinities for Barcode Index Numbers (BINs) using data from various Malaise trap and metabarcoding studies conducted across Germany. Key datasets include the Landklif project and the nationwide German Malaise trap monitoring program, which encompass forests, meadows, agricultural land, and settlements. Additionally, I will incorporate metabarcoding data from forest nature reserves and studies examining closed forests as well as forests with natural and artificial gaps. As these datasets represent Germany’s dominant landscape types and forest conditions, they provide a strong foundation for analysing BIN habitat affinities. By classifying habitat preferences independently of the Biodiversity Exploratories setup, this approach ensures a more robust assessment while minimizing site-specific biases. Beyond forest affinity classification, I will examine the phylogenetic diversity and beta diversity of insect communities to gain deeper insights into ecosystem stability. To track changes in insect communities, I will conduct fieldwork at 21 FOX sites in 2026, using Malaise traps and DNA metabarcoding for species identification. The resulting metabarcoding data will be processed through a standardized workflow, generating a phylogenetic tree and an OTU-sample-read table corrected for sequencing errors. I will investigate whether insect communities shift toward open-habitat assemblages following gap creation and whether deadwood removal intensifies these changes, particularly in species with strong forest affinities. The FOX experiment within the Biodiversity Exploratories provides an ideal framework for disentangling the effects of forest gaps and deadwood removal or accumulation. The study sites include Central Europe’s main tree species under different management intensities, ensuring broad applicability beyond specific forest types. Furthermore, the sites span three regions in Germany with varying climatic conditions, providing a comprehensive ecological perspective.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1374: Biodiversity Exploratories