Harvesting methods shape root and mycorrhizal growth in forest ecosystems

Soil compaction caused by logging activities poses a significant challenge to root systems, their symbiotic interactions with mycorrhizal fungi, and their respective growth through altered biotic and abiotic soil factors. These impacts are closely tied to biogeochemical cycles and carbon sequestration, highlighting the importance of sustainable forestry strategies. Undisturbed forest ecosystems play a key role in enhancing climate resilience and supporting carbon storage, yet knowledge gaps remain in understanding the interplay between soil properties, root growth, and mycorrhizal associations under different harvesting conditions.

In this study, we investigated the effects of soil compaction on root and mycorrhizal dynamics and their implications for carbon cycling and ecosystem function. We implemented different harvesting methods (harvester-forwarder with/without tracks and cable-yarding with motor-manual felling) in a beech-dominated forest in Lower Austria during the winter of 2022/23. Using a transect approach, we assessed spatially explicit impacts on root and mycorrhizal dynamics by installing ingrowth cores and ingrowth bags. Transects were strategically placed across tracks, covering areas directly impacted by logging activities (tracks, cable-yarding corridors) and indirectly affected areas (between wheel tracks, marginal zones). Comprehensive assessments included root biomass, mycorrhizal hyphae distribution, anatomy, and morphology, alongside analyses of logging effects on mycorrhizal morphotypes and root-tip mycorrhization rates.

Preliminary data reveal significant influences of timber harvesting on root and mycorrhizal dynamics, with altered root growth patterns and notable differences between treatments and within transects. Harvesting methods resulted in widely varying degrees of soil compaction, leading to contrasting impacts on fine root characteristics, such as morphology and biomass. These changes, in turn, affect carbon sequestration potential and nutrient cycling processes, emphasizing the critical role of soil health in ecosystem resilience.

The persistent impacts of soil compaction on root and mycorrhizal development underscore the urgent need for sustainable forest management practices that mitigate adverse effects. By preserving soil integrity, such strategies enhance the long-term viability of root and mycorrhizal systems, supporting carbon storage and the broader biogeochemical functions essential for forest ecosystems to meet climate challenges.