Quality evaluation of Nothofagus pumilio seeds linked to forest management and climatic events

Abstract

Background Forest ecosystems undergo signifcant transformations due to harvesting and climate fuctuations, emphasizing the critical role of seeding in natural regeneration and long-term structural preservation. Climate change further amplifes these dynamics, afecting phenology across species and regions. In Tierra del Fuego (Argentina), Nothofagus pumilio (lenga) forests represent the most important timber resource, and it is managed through diferent silvicultural strategies. This species demonstrates notable post-disturbance regeneration, yet seed fall exhibits signif‑ cant variability, leading to variations in seed quality (e.g., viability). This study aims to assess fuctuations in N. pumilio seed quality, determine how it varies concerning forest management strategies, annual productivity, and the cooccurrence of climatic phenomena including El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Results Viable seeds represented 18.4% of the total, notably higher in unharvested than in managed areas. Con‑ versely, empty seeds were more prevalent in harvested areas (>75%). Seed quality exhibited signifcant diferences across silvicultural treatments, except for insect-predated seeds, which had similar proportions across all areas, though dispersed retention showed higher predation. When considering years with varying production levels, high-production years favoured full and viable seeds, particularly in unharvested forests and aggregated retention, while low-production years saw reduced viability across all treatments. Quadratic models revealed that viability increased with seed production, where unharvested forests achieved the highest values. Climate variability infuenced seed proportions, where ENSO+/SAM+promoting more full and viable seeds, while ENSO–/SAM+favoured nonpredated seeds, especially in unharvested stands. Conclusions Seed quality varies among treatments and years with diferent levels of seeding. Variations in seed qual‑ ity, linked to climatic events, infuence seed viability. Seed quality plays a critical role in forest regeneration, ensuring a seedling bank for harvested stands to face climate variability. These fndings are relevant for forest management and ecosystem services, considering the increasing climate variability and extreme events. Understanding these infu‑ ences is crucial for Nothofagus pumilio forests’ sustainability and global forest adaptation strategies.