Moderate- to High-Severity Disturbances Shaped the Structure of Primary Picea Abies (L.) Karst. Forest in the Southern Carpathians

Abstract

Research Highlights: Past disturbances occurred naturally in primary forests in the Southern Carpathians. High- and moderate-severity disturbances shaped the present structure of these ecosystems, which regenerated successfully without forestry interventions. Background and Objectives: Windstorms and bark beetle outbreaks have recently affected large forest areas across the globe, causing concerns that these disturbances lie outside the range of natural variability of forest ecosystems. This often led to salvage logging inside protected areas, one of the main reasons for primary forest loss in Eastern Europe. Although more than two-thirds of temperate primary forests in Europe are located in the Carpathian region of Eastern Europe, knowledge about how natural disturbances shape the forest dynamics in this region is highly essential for future management decisions. Material and Methods: We established our study in a primary forest valley situated in the centre of the largest temperate primary forest landscape in Europe (Făgăraș Mountains). A dendrochronological investigation was carried out to reconstruct the natural disturbance history and relate it to the present forest structure. Results: The dendrochronological analysis revealed high temporal variability in the disturbance patterns both at the patch and stand level. Moderate severity disturbance events were most common (20–40% of canopy disturbed in 60% of the plots) but high severity events did also occur (33% of the plots). Regeneration was spruce-dominated and 71% of the seedlings were found on deadwood microsites. Conclusions: We conclude that the current structure of the studied area is a consequence of the past moderate-severity disturbances and sporadic high-severity events. The peak in disturbances (1880–1910) followed by reduced disturbance rates may contribute to a recent and future increase in disturbances in the Făgăraș Mts. Our findings show that these disturbance types are within the range of natural variability of mountain spruce forests in the Southern Carpathians and should not be a reason for salvage logging in primary forests from this area.

Large old trees increase growth under shifting climatic constraints: Aligning tree longevity and individual growth dynamics in primary mountain spruce forests

“…Although the exacerbated effects of intensifying tree growth‐moisture sensitivity may increase LOT mortality, the adverse effects of rising mortality could be attenuated by the synchronic post‐disturbance tree recruitment and rapid understory growth benefiting from improved growing conditions (e.g., increased light availability), while trees that invested into chemical and anatomical defenses in the past will persist as biological legacies. As an example, the dryer southern Carpathian spruce forests have experienced high‐severity disturbances at the turn of the 20th century (Spînu et al, 2020), yet contain some of the oldest trees, the highest living basal area and mean tree density across the Carpathians.…”

Forest Dynamics after Five Decades of Management in the Romanian Carpathians

“…However, if the average amount of annual precipitation is over 800 mm in the future, fir populations may remain stable, even in the context of global warming [20]. Although disturbances have been considered to be a negative factor in forest ecosystems for many decades due to the damage they cause, they can also have positive effects on both regeneration [39] and species diversity [40].…”