PoToMa

Dead pure spruce stands of medium age – potentials of deadwood management

Lying deadwood treatment

Image: Benjamin Wildermuth

About the project

PoToMa Logo

Graphic: Klara Mrak

Climate change causes rising temperatures, precipitation deficits, and increasingly frequent extreme weather events. These stress factors compromise the vitality of forest stands and promote large-scale bark beetle infestations, particularly in young spruce monocultures, resulting in widespread tree dieback across Germany. The common practice of removing deadwood from such sites causes substantial nutrient losses and can impede natural forest regeneration. At the same time, societal and political expectations regarding forest ecosystem services are rising. The PoToMa project aims to compare different strategies of deadwood management in commercial spruce forests at mid-elevation sites.

The project's central question is whether the retention of standing or lying deadwood creates favorable microsites for seed germination and the establishment of pioneer and target tree species, and how deadwood influences the ecosystem's nutrient dynamics and exports. The objective is to assess whether the retention of dead wood—compared to conventional salvage harvesting practices—promotes sufficient natural forest regeneration while simultaneously providing ecological and economic services, thereby enabling the sustainable development of climate-resilient and economically viable forest stands in calamity areas.

Funding program “Sustainable Renewable Resources” (FPNR)External link of the Agency for Renewable Resources (FNR), funded by the Federal Ministry of Agriculture, Food and Regional Identity (BMLEH)External link.

For collaboration inquiries, please contact Klara Mrak (Coordination): klara.mrak@uni-jena.de.

Subprojects

The 2026 season

Knowledge transfer: Forest research up close
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What ecological effects does standing deadwood have compared with lying logs? How quickly do nutrients become available, and how does this affect forest regeneration and development? How can we measure these processes?
The PoToMa team discussed these questions with interested participants from the Bergwaldprojekt in the Thuringian Forest at the end of September. While volunteers from Bergwaldprojekt e.V. spent a week rewetting the slope mire in the Schmücker Graben as part of the large-scale nature conservation project “Streams, Mires and Mountain Meadows in the Thuringian Forest”, they also visited the nearby PoToMa research plots. The participants were impressed by the diversity of local forest ecology research.

Image: Fabian Löber
PoToMa meets ReForm RegioWald
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Dorothea Peter (PoToMa), together with Florian Steinebrunner, Simon Grieger, and Thomas Medicus (sister project ResEt‑Fi), visited the “ReForm‑regioWald” REGULUS sites in South Westphalia. The experiments presented on how lying deadwood affects the vitality and browsing of young broadleaved trees and the microclimate largely match previous ResEt‑Fi findings and illustrate the positive effects of deadwood on reforestation.

Image: Thomas Medicus
PoToMa meets Bergwaldprojekt e.v.
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The PoToMa project team and Bergwaldprojekt e.V. exchanged visits in the Zukunftswald Unterschönau to share ideas, discuss field methodologies and explore options for joint research on forest ecology and deadwood use. Together they drafted experiments on deadwood as red deer browsing protection and on nitrogen fluxes across differently managed forest stands.

Image: Klara Mrak
1. Meeting of the Wald Allianz
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27. and 28. April 2026: Part of the PoToMa team attended the first meeting of the Forest Alliance (Wald Allianz) in Meiningen, engaging with key stakeholders on ecosystem-based reforestation and forest development.

Image: Klara Mrak
Soil seed bank activation

In March 2026, Katharina Tiebel (TU Dresden) established an experiment on controlled activation of the soil seed bank as a silvicultural regeneration option. The trial tests different intensities of soil scarification to investigate their influence on the activation of the site-specific seed bank, as well as on the establishment of tree species and accompanying vegetation.

Image: Katharina Tiebel
Second soil sampling

Soil science subproject team after a successful soil sampling campaign. From left to right: Tom Spinke, Dorothea Peter, Alex Borrmann, Annika Weigel, Moritz Stammberger. Missing from the photo: Klara Mrak, Johannes Baumeister, Beate Michalzik.

Image: Klara Mrak
Log experiment

In March 2026, Fabian Löber and Markus Bernhardt-Römermann (Vegetation Ecology, FSU Jena) established an experiment using logs at different decay stages. Seeds of various regeneration tree species were sown around the logs, which should differentially influence seedling development through changes in abiotic conditions and resource distribution.

Image: Fabian Löber
Installation of the soil sensors

In early April 2026, snow hampered the installation of soil moisture sensors, as even the soil in the intact spruce stand was still covered by a substantial snowpack. From left to right: M.Sc. students Moritz Stammberger and Alex Borrmann.

Image: Klara Mrak
Snow in April

Part of the PoToMa team was surprised by snow in early April 2026 during the final deadwood manipulations and sensor installation on the experimental plots. From left to right: Fabian Löber, Alex Borrmann, Franz Lippold, Sascha Spaleck, Dorothea Peter.

Image: Klara Mrak

Works in spring 2026 included modifications of the deadwood manipulations, soil sampling, retrieval of litterbags, and installation of sensors.
Image: Fabian Löber
Cleared plot
Image: Klara Mrak
The plot‑wise treatments “cleared plot” and “lying deadwood” (in the background) were created using a harvester.
Image: Klara Mrak
Landscape shaped by the disturbance events of recent years (drought and bark beetle infestation); example from Thuringia.
Image: Alexander Tischer
High stand on the “Standing Deadwood” plot.
Image: Klara Mrak
Klara Mrak and Dorothea Peter (Soil Science, FSU Jena) mapping humus forms..
Image: Sascha Spaleck
Intact spruce stand
Image: Klara Mrak
The spruce trees on the “Intact Spruce” plots form a relatively closed canopy.
Image: Klara Mrak
The plot‑wise treatment “Lying Deadwood” was created using a harvester.
Image: Klara Mrak
Litterbags will be retrieved by M.Sc. student Annika Weigel to investigate soil faunal activity and its effect on decomposition.
Image: Klara Mrak
M.Sc. students Aina Vorberger and Annika Weigel (FSU Jena) on the “Standing Deadwood” plot.
Image: Klara Mrak
M.Sc. students Johannes Baumeister and Alex Borrmann installing the soil sensor network in March 2026.
Image: Klara Mrak