Impacts of canopy openness and forest management intensity on decomposition processes and decomposer communities

• Applicant: Professor Dr. Sebastian Seibold
• Subject Area: Forestry ; Microbial Ecology and Applied Microbiology ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 512286464

Decomposition of necromass (i.e. dead organic matter) is a key ecosystem process as it affects local soil fertility and global carbon cycling. Decomposer communities and the relative contribution of the involved taxa to decomposition differ strongly between types of necromass (e.g. carrion, leaf litter or deadwood). While fungi and invertebrates are primary decomposers of plant necromass, bacteria, invertebrates and vertebrates largely drive carrion decomposition. Environmental factors, such as microclimate which is strongly linked to canopy cover in forests, affect decomposer communities and decomposition rates. Canopy cover is currently decreasing across Europe as a result of increased natural disturbances due to climate change which will likely affect decomposers and decomposition rates but to a yet unknown extent. Further, canopy openness depends on forest management that also determines other structural and compositional characteristics, such as tree species composition. Effects of forest management and canopy openness on decomposer communities and decomposition rates are likely interacting, but our understanding remains limited since effects of forest management and canopy openness have so far been studied independently.In the proposed project we aim to study how canopy openness affects decomposition processes in forests of different management intensity by comparing decomposer communities and decomposition rates between closed-canopy forests and nearby gaps along a gradient of forest management intensity. The Biodiversity Exploratories offer an ideal research platform for this question since they provide a contrast in canopy openness in form of the FOrest gap eXperiment (FOX) combined with a gradient of forest management intensity. We will conduct a decomposition experiment exposing standardized types of deadwood, leaf litter and carrion, measuring decomposition rates and recording decomposer communities. We will quantify the relative contribution of invertebrates and microbes to decomposition by including invertebrate exclusion treatments. Specifically we will study the effects of forest management intensity and canopy openness (i) on decomposition rates, (ii) on decomposer communities, (iii) on the relative contribution of invertebrates and microbes to decomposition and (iv) on the direct and indirect effects (mediated by decomposer communities) on decomposition rates. Our results will complement earlier and ongoing research within and outside of the Biodiversity Exploratories. Our study will be one of the first studying decomposition of three major types of necromass simultaneously which will lead to a more general understanding of this important ecological processes and its response to changing environmental conditions. This improved understanding is needed to predict how nutrient and carbon cycles will change as a result of increasing forest disturbances and changing forest management.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1374: Biodiversity Exploratories
• Co-Investigator: Dr. Matthias-Claudio Loretto