Competitive releases of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) across primary forests of the Carpathian Mountains

Abstract

Competitive releases of understorey trees are an important pathway to canopy recruitment in unmanaged, closed-canopy forests, with significant consequences for resilience of these ecosystems. As climate and disturbance regimes progressively shift, the dynamics of canopy accession are expected to change. However, the response norms of subcanopy trees to competitive release and other developmental drivers have been understudied. To investigate the aggregate effects of multiple factors (i.e., disturbance severity, climate, ontogeny, topography, and calendar year) on growth rates and duration of growth releases, we examined growth patterns of more than 17100 tree cores of European beech and Norway spruce collected on permanent research plots located across primary forest remnants in the Carpathian Mountains. The percentage of canopy removed on the plot was the dominant extrinsic driver of growth during release events for both species, with beech exhibiting a more pronounced positive response than spruce. For both species, growth response was significantly affected by ontogeny-related factors: beech growth primarily increased with diameter at release onset, whereas spruce responded primarily negatively to age at release onset. Size at release onset also emerged as the primary predictor of release duration for both species. Additionally, both species exhibited increases in released growth rates throughout the past century, indicating a relative increase in canopy accession rates. However, it remains uncertain whether this trend will persist under a potential further intensification of disturbance regimes and shifting climatic constraints, particularly as trees on warmer and drier southern slopes already display weaker growth responses to canopy release compared to individuals on less sun-exposed sites.

Keywords

Canopy accession; Competition; Disturbance; Fagus sylvatica; Picea abies; Resilience

Published in

Forest Ecology and Management
2026, volume: 601, article number: 123344
Publisher: ELSEVIER

SLU Authors

• Yumei, Jiang

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    
  • Czech University of Life Sciences Prague

UKÄ Subject classification

Forest Science

Publication identifier

• DOI: https://doi.org/10.1016/j.foreco.2025.123344

Permanent link to this page (URI)

https://res.slu.se/id/publ/144985