Abstract ID: 3.10651 | Accepted as Talk | Talk/Oral | TBA | TBA

Conifer forests at high elevations are often naturally monospecific, yet their stability is increasingly threatened by abiotic and biotic disturbances. Pure, even-aged stands, which are often dense and structurally uniform, are particularly vulnerable, though their stability is crucial to maintain protection against natural hazards. Understanding how natural regeneration and stand structure respond to environmental conditions and management is essential for predicting future forest dynamics and ecosystem services.
This study presents findings from a long-term experiment established in the 1980s in mature Norway spruce-dominated protective forests spanning montane and subalpine zones in Switzerland and Liechtenstein. The composition of the studied stands is typical for the Alpine region. The experiment aimed to assess how stand structure and regeneration dynamics respond to thinning. Each site included control stands with no intervention and one to two treatment stands with different thinning intensities. Stand structure has been repeatedly surveyed since the late 1980s. Regeneration was initially assessed in the early 2000s, with a reassessment in 2023, following a permanent grid system.
Four decades after thinning, stands exhibited structural characteristics that may enhance long-term stability compared to controls, although trade-offs may exist with resistance to disturbances and protective effect against natural hazards in the short term. Regeneration densities and species diversity increased following thinning, with variation across sites driven by topography, environmental conditions, and browsing pressure. Our results suggest that thinning-induced shifts in stand structure influence competitive interactions and resource availability, affecting regeneration dynamics and the capacity of these forests to recover from disturbance and provide critical ecosystem services.
Our findings contribute to a better understanding of how thinning as a management approach can enhance structural complexity and regeneration diversity in high-elevation protective forests, influencing their long-term stability and capacity to reduce natural hazard risks. These insights are relevant for the development of management strategies to strengthen forests’ protective functions under climate change.